Biomedical subjects

Josef Flammer

Publications and source records attributed to Josef Flammer.

59 records · Page 4Linked to original sources

PubMedDate not supplied

Transient raise of endothelin-1 plasma level and reduction of ocular blood flow in a patient with optic neuritis.

PURPOSE: To analyze how far an ischemic component might have been involved in optic neuritis. METHODS CASE REPORT: a 32-year-old man with symptoms characteristic for optic neuritis underwent extensive clinical, laboratory/serological and vascular examination for systemic associations and vascular involvement. RESULTS: The patient was found to have a temporary ocular blood flow dysregulation and increased plasma endothelin-1 levels which decreased after the acute phase of the optic nerve. CONCLUSIONS: We conclude that there might be an ischemic component in this patient with optic neuritis and hypothesize that this ischemic component is at least in part due to a temporarily increased endothelin-1 level.

Adult↗

PubMedDate not supplied

Ascorbic acid as a free radical scavenger in porcine and bovine aqueous humour.

AIM: To study the antioxidant activity, UV absorption, concentration and stability of ascorbic acid (AA) in porcine and bovine aqueous humour (AH). METHODS: Porcine and bovine AH was taken within 5 min after death and frozen at -70 degrees C. The characteristic UV absorption band of AA and the concentration of AA in AH was determined by UV spectrophotometry. The antioxidant activity of AA to serve as a free radical scavenger in AH has been determined by using a novel fluorescent probe for antioxidants, the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO). The fluorescence lifetime and intensity of this probe reflect the concentration of dissolved antioxidants. The time-resolved fluorescence of DBO (laser excitation at 351 nm) in AH and in a neutral phosphate-buffered saline (PBS) solution containing only the natural amount of AA as an additive were measured. RESULTS: The characteristic UV absorption band of AA has its maximum at 266 nm in AH. The concentration of AA in porcine and bovine AH was found to be 0.547 +/- 0.044 and 1.09 +/- 0.16 mM, respectively, by spectrophotometry. The fluorescence lifetime of the probe DBO was reduced from 320 +/- 5 ns in pure aerated PBS to 205 +/- 5 ns in porcine AH and 165 +/- 3 ns in bovine AH. A detailed kinetic analysis of the lifetime shortening suggests that AA contributes approximately 75 and 85% to the antioxidant activity of porcine and bovine AH, respectively. CONCLUSIONS: Our experiments suggest that AA is the major contributor to the antioxidant activity of porcine and bovine AH. The role of AA to serve as an antioxidant in AH is discussed. In addition, UV spectrophotometry is established as an alternative method to determine the concentration of AA in AH.

Animals↗

PubMedDate not supplied

Immunohistochemical localization of angiotensin-converting enzyme, angiotensin II and AT1 receptor in human ocular tissues.

We investigated the immunohistochemical distribution of 3 components of the renin-angiotensin system (RAS), angiotensin-converting enzyme (ACE), angiotensin II (AngII) and AT1 receptor (AT1), in the human eye. ACE and AngII were localized to nonpigmented epithelial cells of the ciliary body, to endothelial and epithelial cells of the cornea, to epithelial cells of the conjunctiva and to trabecular meshwork cells in the anterior part of the eye. In the posterior part of the eye, ACE and AngII were localized to ganglion cells, some cells in the inner nuclear layer, photoreceptor cells and to endothelial cells of the retinal and choroidal vessels. The overall intensity of AT1 immunoreactivity was weak in all ocular tissues, but the main localization was in ganglion cells. As a preliminary investigation, we were able to include 2 Alzheimer's disease (AD) cases. In AD, no differences from controls were found in the cellular distribution and staining intensity of all 3 antigens. The manifold localization sites of the observed antigens point to rather generalized functions of the RAS in human ocular tissues, such as regulatory effects on neuronal cells, vessels and vitreous humor homeostasis.

Aged↗

PubMedDate not supplied

Activated STAT 3 in choroidal neovascular membranes of patients with age-related macular degeneration.

PURPOSE: The Jak/STAT (Janus tyrosine kinase/signal transducers and activators of transcription) pathway is critical for growth control, developmental regulation and homeostasis. Here we studied the expression of STAT proteins in the proliferative disease of age-related macular degeneration (AMD) with choroidal neovascular membranes (CNVM). The STAT family are of cytoplasmic proteins with roles as signal messengers and transcription factors that participate in normal cellular responses to cytokines and growth factors. Abnormal activity of certain STAT family members, particularly STAT 3 and STAT 5, is associated with a wide variety of human malignancies and other diseases. Here were studied STAT activation in CNVM of patients with AMD. METHODS: Sections of formalin-fixed, paraffin-embedded samples from 8 eyes with AMD and 5 controls were included in this study. Immunohistochemical staining was performed using antibodies against activated STAT 1, STAT 3 and STAT 5 proteins, and tenascin. RESULTS: In CNVM, we observed a strong positive staining for tenascin and STAT 3 in retinal pigmented epithelial (RPE) cells restricted to areas of developing scars. In contrast, STAT 3 immunoreactivity failed in areas completely composed of fibrovascular disciform scar material. In addition, no immunoreactivity for both STAT 1 and STAT 5 was detected in all CNVM and in all control samples. CONCLUSION: In CNVM, activation of STAT 3 appears in RPE cells simultaneously with the formation of scars.

Aged↗

PubMedDate not supplied

Therapeutic strategies for normal-tension glaucoma.

Treatment of normal-tension glaucoma has been a subject of debate for several years. Glaucomatous damage cannot be influenced directly, and current treatment modalities in normal-tension glaucoma are aimed at the control of risk factors. Intraocular pressure is a widely accepted risk factor and its reduction can improve the prognosis in normal-tension glaucoma patients. The repeated demonstration of the importance of hemodynamic factors in normal-tension glaucoma has, however, not been paralleled by a comparable progress in the development of therapeutic modalities capable of influencing favorably ocular blood flow. Today, calcium channel blockers seem to be the most promising adjunctive treatment to be considered in patients with glaucomatous optic neuropathy without increased intraocular pressure.

Eye↗