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  • 1
    Electronic Resource
    Electronic Resource
    Therapeutic use of the 193-nm excimer laser in corneal pathologies (1997)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 235 (1997), S. 296-305 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract • Purpose: To analyze the results of phototherapeutic keratectomy. • Patients and methods: We performed 193-nm excimer laser phototherapeutic keratectomy (PTK) in 252 eyes of 216 patients suffering from pain and/or decrease in visual acuity. One hundred and three eyes had recurrent erosions of the cornea, 86 eyes underwent excimer laser smoothing of the cornea after pterygium surgery, 29 eyes had a bandlike keratopathy (25 rough, 4 smooth) and 34 eyes had other pathologic conditions such as amyloidosis of the cornea, anterior corneal dystrophies, scars after injuries, alkali burns, superficial stromal dystrophies and infections. Recurrent erosions and epithelial dystrophies were treated with 15–20 pulses (160–200 mJ/cm2, 8 mm ablation zone) after mechanical abrasion of the epithelium. Removal of corneal opacities and scars required the use of a masking fluid (methylcellulose) in different concentrations and slit-lamp control (integrated in the delivery system of the excimer laser). • Results: Some 91% of the eyes with recurrent erosions were recurrence-free. Fifty-two per cent of the eyes with pterygium had recurrences if the baresclera technique was used and 33% of the eyes if a free conjunctival graft was used. The difference was not significant. All of the patients with bandlike keratopathy were pain-free. In 88% of the eyes with special indications the treatment goal was achieved. No positive effect was seen after alkali burn, in a patient with anterior membrane dystrophy (Grayson-Wilbrandt corneal dystrophy) or in a patient with a corneal protuberance. In one patient with scleroperikeratitis a late recurrence of the opacity was observed 3 years after surgery. A loss of best corrected visual acuity was found only in one patient with bullous keratopathy in whom the treatment goal was the reduction of pain. All patients with smooth bandlike keratopathy had an improvement in best corrected visual acuity of at least one line. About 70% of patients with special indications improved by at least one line, up to nine lines. A possible hyperopic shift in all groups could be minimized using a large ablation zone. • Conclusion: PTK with the 193-nm excimer laser is a safe and effective treatment for many superficial diseases of the cornea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01739639
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrasonography as a routine examination before treatment of retinal detachment due to macular hole (1986)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 224 (1986), S. 226-229 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twelve of 25 patients were treated at the University Eye Clinic in Münster because of retinal detachment due to a macular hole. Partial fluid gas exchange (SF6), vitrectomy and SF6, or vitrectomy and silicone instillation, were used, and the patients were examined both pre- and postoperatively by ultrasonography with particular attention to the situation at the posterior pole. These echographical examinations enabled us to evaluate the following three criteria: (1) staphyloma posticum, (2) stiffness of the retina, and (3) vitreous adhesions. All of these conditions mean that the prognosis will be worse if SF6 gas instillation is used alone. In these cases, a vitrectomy should also be performed or a Klöti-Klemme procedure is useful when stiffness of the retina or staphyloma posticum is present. Preoperative ultrasonography is useful when setting up an adequate therapy plan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02143059
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  • 3
    Electronic Resource
    Electronic Resource
    ‘ValleyScan’: A new two-bond drive technique for the calculation of potential energy surfaces with less computational effort (1992)
    Springer
    Journal of computer aided molecular design 6 (1992), S. 505-512 
    Details
    ISSN: 1573-4951
    Keywords: Benzo[b]naphtho[1,2-d]pyran ; Helimerization barrier ; Potential energy surface ; Ring inversion ; Chiral transition state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel, CPU-time inexpensive two-bond drive technique, called ‘ValleyScan’ [1], is described. It makes it possible to omit the chemically nonrelevant points of high energy, which are normally part of a two-dimensional (2D) grid calculation. The new procedure works well for the calculation of the ring inversion of cyclic molecules, but should also be useful for other ‘two-bond’ problems e.g. side-chain movements in larger molecules (e.g. proteins). The algorithm is based upon pseudocode description and can easily be included in any molecular modelling software with an open user interface. Starting from an energy minimum, the calculation scans the potential surface in all directions up to a user-defined energy limit. With this strategy, attention is paid only to the area close to the stationary points-energetically higher structures do not have to be calculated. We applied the procedure to the test molecules 1,3-cyclohexadiene (4), 2H-pyran (5) and 6H-dibenzo[b,d]pyran (6). The extension of this method to the variation of more than two dihedral angles for more complex problems, e.g. sterically more hindered rotation, is in progress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00130400
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  • 4
    Electronic Resource
    Electronic Resource
    Tränenwegsoperationen im Kindesalter Retrospektive Studie an der Universitäts-Augenklinik Münster*,** (1997)
    Springer
    Der Ophthalmologe 94 (1997), S. 587-590 
    Details
    ISSN: 1433-0423
    Keywords: Schlüsselwörter Tränenwegschirurgie ; Kindesalter ; Key words Surgery of the lacrimal system ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Surgery on the lacrimal system in 296 children was performed at the Münster University Eye Hospital from 1987 to 1992. Patients and methods: The age of the patients, etiology of the obstruction and surgical strategy were analyzed retrospectively. A questionnaire was sent to the parents to allow evaluation of the results and subjective satisfaction. Results: A total of 181 questionnaires was sent back to our hospital (results of 210 operations, including 24 preoperations). Of the 124 children were up to 3 years old. 197 obstructions were congenital, 7 traumatic, 4 results of inflammation, and 2 iatrogenic. In 184 patients we performed intubation with silicon tubing. Seven patients had canalicular surgery, and 19 patients had dacryocystorhinostomy (DCR). After intubation 87.5% of patients were practically without complaints, after canalicular surgery 85.7% and after DCR 78.9%. Five patients suffered from severe problems and had to be reoperated.
    Notes: Tränenwegsoperationen an der Universitäts-Augenklinik Münster von 296 Kindern aus den Jahren von 1987 – 1992 wurden untersucht. Patienten und Methode: Alter der Patienten, Ätiologie und die Operationsmethoden wurden retrospektiv ausgewertet. Um die Operationsergebnisse und die subjektive Zufriedenheit zu erfassen, wurden an die Eltern der Patienten Fragebögen verschickt. Ergebnisse: 181 Fragebögen (Ergebnisse von 210 Operationen, davon 24 Voroperationen) wurden zurückgeschickt. 124 Kinder waren bis zu 3 Jahre alt. 197 Stenosen wurden kongenital, 7 traumatisch, 4 entzündlich und 2 iatrogen bedingt. 184 Tränenwegsspülungen mit Intubationen (I) der Tränenwege, 7 Canaliculusrekonstruktionen und 19 Dakryozystorhinostomien (DCR) wurden durchgeführt. Praktisch beschwerdefrei waren 87,5% der Patienten mit Tränenwegsintubation, 85,7% nach Canaliculusrekonstruktion und 78,9% nach DCR. 5 Patienten mußten wegen anhaltender starker Beschwerden ein zweites Mal operiert werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003470050164
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  • 5
    Electronic Resource
    Electronic Resource
    Corneal haze after mechanical debridement for overcorrection after myopic photorefractive keratectomy (1996)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 234 (1996), S. 278-279 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 47-year-old man had photorefractive keratectomy (PRK) to correct myopia. Three months after surgery he was slightly overcorrected with +1.25–0.5/170°. He then suffered a gout attack and showed a refraction of +2.5–0.5/4° which decreased to +1.75–0.5°. To reduce this permanent overcorrection we performed mechanical debridement of the corneal epithelium. the patient had haze grade 2–3 after 2 weeks and haze grade 0–1 some 4 month later. The refraction was +1–0.5/25°. This case report indicates that mechanical debridement is able to reduce overcorrection after PRK and bears a risk of haze formation comparable to that associated with PRK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430423
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoselektivität von Photocycloadditionen, 5[1] Photoreaktionen zwischen 2-Cyclopenten-1-on und Enolethern (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 933-940 
    Details
    ISSN: 0009-2940
    Keywords: [2 + 2] Photocycloaddition ; Selectivity, stereo-, regio- ; 1,4-Biradicals ; INADEQUATE ; Calculations, AM1, FINITE ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivity in Photocycloaddition Reactions, 5[1]. - Photoreaction of 2-Cyclopenten-1-one with Enol EthersThe regio- and stereoselectivity of [2 + 2] photocycloaddition reactions between 2-cyclopenten-1-one (1) and the electron-rich alkenes: ethyl, isopropyl, and phenyl vinyl ether (2-4) as well as 2,3-dihydrofuran (10) were examined. In all cases the annulated cyclobutene derivatives 5-7 and 11 were isolated in yields between 70 and 99%. The regioisomeric HT/HH products were formed in a ratio of 3:1 to 4:1. For the determination of the product stereochemistry, INADEQUATE and 1H,1-decoupling experiments were performed. Computer-assisted investigations on the molecular geometry and 1H,1H-coupling constants were performed by using semiempirical methods (AM1, FINITE). The HT regioisomers were formed with moderate endo diastereoselectivity, whereas in the case of the HH regioisomers both diastereomers (exo/endo) were formed in equal amounts. Photoreaction with 2,3-dihydrofuran (10) led to almost exclusive formation of exo-diastereomeric HH and HT regioisomers 11. The observed stereoselectivity is rationalized by the optimal geometry of the intermediate triplet 1,4-biradicals during intersystem crossing.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250427
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  • 7
    Electronic Resource
    Electronic Resource
    Acetogenic isoquinoline alkaloids, XXI. An atropisomer-differentiating reaction for the chemical analysis of axial chirality and its computational investigation: Proof of the stereostructure of dioncophylline ADedicated to Professor Dr. Dr. h. c. mult. Siegfried Hünig on the occasion of his 70th birthday. (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 803-809 
    Details
    ISSN: 0170-2041
    Keywords: Alkaloids ; Axial chirality, determination of ; Calculations, AM1, MM2, MMX ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chemical method for the unambiguous elucidation of axial chirality in naphthylisoquinoline alkaloids such as dioncophylline A (1a) is described. It involves synthetic connection of the stereogenic axis to be investigated with the stereocenters present in the same molecule. The resulting macrocyclic ansa compound 7c is formed in high yield, yet exclusively for only one of the two atropodiastereomers (4c), the other isomer (4b) does not cyclize at all. This cyclization behavior fully confirms the stereostructure 1a of dioncophylline A, as postulated by us earlier. For an interpretation of the striking atropisomer specificity of this ring closure reaction, computer-assisted theoretical investigations on the molecular geometries and thus thermodynamical properties of both of the imaginable cyclization products 7b/c have been performed by using force-field (MM2, MMX) and semiempirical methods (AM1). The optimized structures show the obtained macrocycle 7c to be a nonstrained, stable compound, whereas the other possible product 7b (which definitely is not formed) should be severely distorted.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1991199101137
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