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Biomedical subjects

A J Augustin

Publications and source records attributed to A J Augustin.

At least 19 recordsLinked to original sources
PubMed2003

[Is a cataract avoidable? Current status with special emphasis on the pathophysiology of oxidative lens damage, nutritional factors, and the ARED study].

The benefit of long-term nutrient intake to reduce the risk of age-related ocular disease such as cataract or macular degeneration is subject to controversy. Conclusions about the benefits and risks of antioxidant supplements can be expected after reviewing the current literature concerning oxidative-induced lens damage and nutritional effects. Identification of influenceable risk factors for senile cataracts could achieve immense economical relevance. In contrast to former longitudinal epidemiological studies, the AREDS report failed to verify protective properties of highly concentrated vitamin supplements on cataract formation. Although there are enough epidemiological indications for reducing the risk of cataracts by the intake of antioxidants, a general recommendation for the use of supplements is untimely or even wrong until stringent evidence of efficacy is provided. The usefulness of cataract prevention is discussed.

Animals↗
PubMed2003

Endotoxins in ophthalmic viscosurgical devices.

PURPOSE: To measure the endotoxin concentration (EC) of 25 commercially available, hyaluronic acid- and hydroxypropylmethylcellulose-based (HPMC) ophthalmic viscosurgical devices (OVDs). METHODS: The in vitro Limulus amebocyte lysate (LAL) assay, which indicates the presence of endotoxins originating from gram-negative bacteria, was used to determine the EC. The procedure was performed according to the European Pharmacopoeia/USP. EC including duplicate determinations, negative controls, dilution series with control standard endotoxin, dilution series with sample extract and positive sample control. RESULTS: 16 OVDs (Amvisc, Amvisc Plus, Biolon, Coatel, Healon, Healon GV, Healon, HPMC Ophtal L, Microvisc, Microvisc Plus, Ocucoat, Provisc, Rayvisc, Viscoat, Visco Shield 2%, Visko 1.4%) had an EC under 1.2 endotoxin units/mL, five (Adatocel, HPMC Ophtal H, LA Gel, Viscorneal, Viscorneal Plus) had an EC > or = 1.2 and < or = 24 EU/ml, and four (Biocorneal, Dispasan also named Ophthalin, Dispasan Plus, Visko 1%) had an EC of > 24 EU/ml. DISCUSSION: To avoid viscoelastic-related inflammatory or immunological reactions, the use of pure OVDs is recommended, especially for surgical procedures with an inherent possibility of leaving viscoelastic remnants in the eye (e.g., cataract surgery, visco-canalostomy or penetrating keratoplasty).

Endophthalmitis↗
PubMed2003

Immunological effects of allopurinol in the treatment of experimental autoimmune uveitis (EAU) after onset of the disease.

PURPOSE: Allopurinol reduces oxidative tissue damage and exerts immunomodulating effects in the treatment of experimental autoimmune uveitis (EAU). However, the mechanism of the immunologic pathway remains unclear. In previous studies, treatment was started at the time of immunization. Therefore, whether allopurinol prevents the onset of the disease (i.e., acts in a protective manner) is not known. METHODS: Sixteen male Lewis rats were used: 6 EAU without therapy [control]; 4 EAU with allopurinol treatment starting 7 days after immunization [AL7]; and 6 EAU with allopurinol treatment starting 11 days after immunization [AL11]. Their sera were tested against Western blots of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of retinal proteins. Based on digital image analysis, analysis of discriminance was done. RESULTS: There were significant immunomodulating effects in both therapy groups (Wilks' lambda 0.001, P < 0.008) compared to controls. However, the effects were more pronounced in the AL7 group, where peak intensities and the number of peaks were markedly more reduced. CONCLUSIONS: Immunomodulating effects of allopurinol can be detected even if the therapy starts after the onset of the disease. Thus allopurinol strongly influences the immunologic mechanism in this model of autoimmune disease. In view of its minimal side effects, the drug could be a promising alternative for the therapy and prophylaxis of uveitis and other autoimmune diseases.

Adjuvants, Immunologic↗
PubMed2002

Changes in the tear proteins of diabetic patients.

BACKGROUND: Previous studies have shown a significant increase in tear protein peaks in the tears of diabetic patients suffering from dry eye. The aim of this study was to analyze the tear protein patterns from patients with diabetes mellitus who do not suffer from ocular surface diseases (DIA). METHODS: A total of 515 patients were examined in this study (255 healthy subjects (controls) and 260 patients suffering from diabetes mellitus). Tear proteins were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. After digital image analysis densitometric data files were created and subsequently used for multivariate statistical procedures. RESULTS: A significant increase in the number of peaks was detected in diabetic patients compared to controls (P < 0.0003). The analysis of discriminance revealed a highly significant discrimination between diabetic patients and controls (Wilks lambda: 0.27; P < 0.000001). Furthermore, a significant difference in the protein pattern of diabetic patients could be detected between those suffering from dry eye or not (P < 0.002). The changes in protein patterns of diabetic patients increased with the duration of the diabetic disease. In diabetic patients with a disease duration longer than 10 years the changes were significantly more expressed than in patients with a shorter diabetic history (P < 0.003) and in healthy subjects (P < 0.0001). CONCLUSIONS: The tear protein patterns of diabetic patients are very different in the number and intensity of spots from those of healthy subjects. Furthermore, it could be demonstrated that the differences found in the tear patterns of diabetic patients are not equal to those found in previous studies in patients suffering from dry-eye disease. The alterations in the diabetic tears were correlated with the duration of the diabetic disease. With longer disease, history changes in the tear protein patterns increased. With the course of the disease some protein peaks appeared that are not present in healthy persons. Our study shows that the analysis of electrophoretic tear protein patterns is a new non-invasive approach in the early diagnosis and analysis of the pathogenesis of diabetes induced ocular surface disease.

Diabetes Mellitus↗
PubMed2001

Two-dimensional analysis of tear protein patterns of diabetic patients.

In diabetic patients, dry eye and other ocular surface diseases occur more often than in healthy subjects. The aim of this study was to analyze the tear protein patterns of patients suffering from diabetes mellitus type II (dia) and to compare them to the patterns of healthy volunteers (ctrl). Tear proteins of nonstimulated tears of 20 patients (ctrl n=10, dia n=10) were separated using two-dimensional electrophoretic techniques. The protein patterns of each group were analyzed by a multivariate analysis of discriminance. Furthermore, for all spots of each gel, a 50 x 50 variables pH/Mr (molecular weight) array was generated and subsequently analyzed by a multivariate analysis of discriminance. Additionally, an artificial neural network was trained using the matrix data as input and a sensitivity analysis was performed to figure out, which spots were the most important to differentiate between the tear protein patterns. In both groups a complex staining pattern could be obtained. In diabetic patients significantly more spots were detected compared to the control group (P<0.02). The analysis of discriminance found a highly significant difference between dia and ctrl (P<0.00001). Using the matrix data, the analysis of discriminance showed a significant difference between the two groups, too (P<0.0001). The sensitivity analysis by means of the artificial neural network revealed several spots that were more expressed or more frequently present in the diabetic group. Our findings reveal that the composition of tear proteins of diabetic patients is different from that of healthy subjects. The use of the two-dimensional electrophoretic technique could give more insight into the diabetic-related changes in the tear film composition.

Adult↗
PubMed2001

Analysis of tear protein patterns of dry-eye patients using fluorescent staining dyes and two-dimensional quantification algorithms.

Tear proteins of nonstimulated tears of 29 patients (healthy subjects, n = 8; dry-eye syndrome patients, n = 12; diabetic dry-eye patients, n = 9) were electrophoretically separated and stained by SYPRO Orange, followed by Coomassie blue staining. Both, the fluorescent and the Coomassie stains were subsequently analyzed by an automated two-dimensional algorithm for finding and quantification of peaks and by a discriminant analysis. Using SYPRO Orange, an average number of peaks/sample between three (at 200 ms) and 15 (at 3000 ms) could be found. In comparison, Coomassie staining resulted only in an average number of six peaks/sample. This corresponds to a sensitivity obtained at approx. 400-600 ms exposure time of SYPRO Orange stained gels. For all exposure times, the protein patterns of the three clinical groups were statistically significantly different from each other (P < 0.05). Only at 200 ms the distances between the groups decreased slightly. The Coomassie-stained gels revealed only a mid range discrimination power similar to that of 200-400 ms exposure in the fluorescing gels. The use of SYPRO Orange provides faster results than those obtained by Coomassie staining. In addition, the sensitivity of staining can be varied even in the same gel by changing the exposure time. The use of the two-dimensional algorithm allows to distinguish between the three clinical groups in accordance to earlier studies using one-dimensional densitographic raw data. Thus, the high speed of evaluation and the more sensitive results as compared to earlier studies could be a step further in the use of tear protein patterns in the diagnosis of DRY.

Dry Eye Syndromes↗
PubMed2001

[Phacoemulsification and vitrectomy with the erbium:YAG laser and phacoemulsification with the neodymium:YAG laser].

There are an increasing number of possible applications for the use of Erbium:YAG and Neodymium:YAG lasers in ophthalmology. Laser-phacoemulsification as well as Erbium-laser vitrectomy is of major interest. We report on the underlying technology and more than 1-year-experience using the PHACOLASE (Asclepion-Meditec, Jena, Germany, 10-100 Hz frequency, 5-50 mJ single pulse energy) for phacoemulsification and pars plana vitrectomy and the Lyla-Dodick laser photolysis (A.R.C. Laser, Eckental-Forth, Germany, 1-20 Hz, up to 8 mJ single pulse energy). The Erbium:YAG-laser as well as the Neodymium:YAG-laser enabled us to extract lenses with up to medium hard nuclei. Moreover, the Erbium laser enabled fast vitrectomy with little mechanical traction. In many of our initial surgical operations we had to change to mechanical vitrectomy due to initial technical problems. No new complications occurred intra- or postoperatively. The handpiece worked well in removing vitreous bodies, but was not feasible for cutting membranes. Modified handpieces for this purpose are under development.

Equipment Design↗
PubMed2001

Late opacification of the foldable hydrophilic acrylic lens SC60B-OUV.

OBJECTIVE: To investigate the cause of severe central opacification in 41 foldable acrylic intraocular lenses (IOLs) requiring explantation. Another IOL was opacified in the original sealed vial. DESIGN: Case series and laboratory analysis. TESTING: Light microscopy, high performance liquid chromatography, sodium dodecyl sulfate polyacoylamide gel electrophoresis, spectrometric analysis, and autoclaving. RESULTS: Neither fatty acids nor proteins could be identified within the IOLs. Spectrometric analysis yielded absorption peaks in the ultraviolet spectral range. CONCLUSIONS: The spectroscopic findings indicate premature aging of the ultraviolet blocking agent. The source of the opacification is a change in the IOL material itself.

Acrylic Resins↗
PubMed2001

Healon5 viscoadaptive formulation: Comparison to Healon and Healon GV.

PURPOSE: To compare the rheological characteristics of a viscoadaptive viscoelastic formulation with those of 2 standard ophthalmic viscosurgical devices (OVDs). SETTING: Department of Ophthalmology, Johannes Gutenberg-University, and Max Planck-Institute for Polymer Research, Mainz, Germany. METHODS: An independent comparative study of 3 OVDs of sodium hyaluronate (Healon(R), Healon GV(R), and Healon(R)5) was performed using the Advanced Rheometric Expansion System to analyze rheologic behavior (eg, dynamic frequency dependence of the complex viscosity) as well as rheological parameters (eg, viscosity at zero shear rate, pseudoplasticity, relaxation time, elastic and viscous modulus). RESULTS: Mean viscosity at zero shear rate was 243 Pas +/- 5 (SD) for Healon, 2451 +/- 12 Pas for Healon GV, and 5525 +/- 14 Pas for Healon5. Mean pseudoplasticity was 173 +/- 7, 754 +/- 10, and 591 +/- 6, respectively. Mean relaxation time was 21 +/- 3 sec, 83 +/- 4 sec, and 88 +/- 6 sec. At low shear rates, viscosity and elasticity (elastic and viscous modulus) increased from Healon through Healon5. Healon5 exhibited a dynamic behavior of the complex viscosity dependent on the duration of the shear rate exposure: At low shear rates, it slowly built up a high viscosity. At higher shear rates, it demonstrated a lower viscosity that decreased further during constant exposure to a specific shear rate. CONCLUSIONS: Healon5 had the highest viscosity and elasticity when exposed to low and high shear rates. These characteristics maintain anterior chamber depth. Also, the high viscosity of Healon5 exhibited a dynamic frequency dependence. In the presence of turbulence and phaco power (continuous high shear rates), it became dispersive by fragmentation and formed a cavity with an outer retentive shell. The cohesive and dispersive properties of Healon5 make it the best of the 3 OVDs evaluated for use at all stages of phacoemulsification.

Chemistry, Pharmaceutical↗
PubMed2001

[Effect of retinal coagulation status on oxidative metabolite and VEGF in 208 patients with proliferative diabetic retinopathy].

BACKGROUND: Oxidative metabolites and different cytokines are believed to be involved in the pathogenesis of (proliferative) diabetic retinopathy. It was the aim of this study to analyze vitreous body and proliferations of diabetic patients for oxidative metabolites and VEGF und to correlate these values to the retinal coagulation status. PATIENTS AND METHODS: The study was performed in 208 patients vitrectomized for diabetic retinopathy (Type I: n = 114, Type II: n = 94). Grouping of patients was performed according to retinal coagulations status: (1) no or minimal preoperative coagulation [mean coagulation area, CA: 156 mm2], (2) coagulation (scatter laser coagulation und/oder cryopexy) < 3 months before surgery [CA: 589 mm2]. (3) coagulation > 3 months before surgery [CA: 546 mm2]. In the vitreous body and, if present, in the fibrovascular proliferations (Type I: n = 83; Type II: n = 73) the level of lipid peroxides (LPO, measured with two methods) and VEGF was determined. RESULTS: In the vitreous body LPO in group 1 were significantly (P < 0.01 (Type I und II)) higher as compared to other groups. In group 3 LPO were significantly lower as compared to group 2 (P < 0.01 (Typ I) and P < 0.05 (Typ II)). Similar results were observed in the proliferations. In Type I patients VEGF values were significantly (P < 0.01 for group 1 vs. 2 and groups 1/2 vs. 3) reduced following coagulation and coagulation + 3 months. In Type II patients only group 3 was significantly (P < 0.01) different from group 1. In proliferations groups 2 and 3 were significantly different from group 1 (P < 0.05 for Typ I and Type II patients). CONCLUSIONS: The time course of the values leads to the conclusion that oxidative metabolites are able to directly modulate growth activity and to exert this effect via induction of VEGF. This hypothesis has to be confirmed in vitro and by means of a prospective study.

Diabetes Mellitus↗