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Biomedical subjects

J Reiner

Publications and source records attributed to J Reiner.

At least 19 recordsLinked to original sources
PubMed2001

Aldehydic lipid peroxidation products derived from linoleic acid.

Lipid peroxidation (LPO) processes observed in diseases connected with inflammation involve mainly linoleic acid. Its primary LPO products, 9-hydroperoxy-10,12-octadecadienoic acid (9-HPODE) and 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE), decompose in multistep degradation reactions. These reactions were investigated in model studies: decomposition of either 9-HPODE or 13-HPODE by Fe(2+) catalyzed air oxidation generates (with the exception of corresponding hydroxy and oxo derivatives) identical products in often nearly equal amounts, pointing to a common intermediate. Pairs of carbonyl compounds were recognized by reacting the oxidation mixtures with pentafluorobenzylhydroxylamine. Even if a pure lipid hydroperoxide is subjected to decomposition a great variety of products is generated, since primary products suffer further transformations. Therefore pure primarily decomposition products of HPODEs were exposed to stirring in air with or without addition of iron ions. Thus we observed that primary products containing the structural element R-CH=CH-CH=CH-CH=O add water and then they are cleaved by retroaldol reactions. 2,4-Decadienal is degraded in the absence of iron ions to 2-butenal, hexanal and 5-oxodecanal. Small amounts of buten-1,4-dial were also detected. Addition of m-chloroperbenzoic acid transforms 2,4-decadienal to 4-hydroxy-2-nonenal. 4,5-Epoxy-2-decenal, synthetically available by treatment of 2,4-decadienal with dimethyldioxirane, is hydrolyzed to 4,5-dihydroxy-2-decenal.

Air↗
PubMed2001

Standardized terminological services enabling semantic interoperability between distributed and heterogeneous systems.

The interconnection of heterogeneous computer applications in medicine raises the issue of semantic interoperability, going beyond traditional approaches of terminological standardization in basically three aspects. First, the variety of medical vocabularies that currently coexist in different domains is a major barrier for the integration of autonomously developed applications. Fortunately, with the Unified Medical Language System (UMLS) there are machine-readable terminological sources that cover and integrate most of the existing medical vocabularies. Second, the exchanged data need to be processed by a machine for different purposes like patient data integration, access to literature and knowledge bases as well as clinical audit and research. Medical vocabularies provided as passive dictionaries are no longer sufficient. Software system developers should take advantage of terminological services for refining user queries, for mapping the user's terms to appropriate medical vocabularies etc. Third, the services should be accessible uniformly and transparently. In the CORBAmed initiative a proposal for a standardized interface for querying and accessing computerized medical terminology resources was created. Based on the mentioned principles the MUSTANG system (Medical UMLS based Terminology Server for Authoring, Navigating and Guiding the Retrieval to Heterogeneous Knowledge Sources) has been developed. It is implemented on a Windows NT platform using the ORACLE database management and development software. The terminological services are accessible via multiple interfaces. The MUSTANG-System and the experiences with using terminological services in practice are described. Opposed to other levels of standardization like syntactical message standards there is much more a hesitation in the use of standardized terminology.

Humans↗
PubMed1999

Application of lipase-catalyzed regioselective esterification in the preparation of digitonin derivatives.

The oligosaccharide chain of the monodesmosidic haemolytic saponin digitonin (1) undergoes an efficient and regioselective acylation in organic solvent by use of Novozym 435 (lipase B from Candida antarctica supported on acrylic resin) in the presence of an activated ester. With vinyl acetate, acetylation occurs at C-6 OH of glucose(II) and C-4 OH of xylose to afford the previously unreported diacetyl derivative 2 and the monoacetyl derivatives 3 and 4. With vinyl laurate only the monolauryl derivative 5 is formed. The structures of these acylated digitonins have been established using modern 2D NMR techniques, which allowed complete assignments of all proton resonances. The hemolytic activity of derivatives 2-5 is significantly reduced compared to that of digitonin.

Animals↗
PubMed1997

[Dark adaptation for evaluating visual performance at twilight using the Trendelenburg eyeglasses].

Dark adaptation for testing visual acuity under mesopic conditions can be accomplished with Trendelenburg spectacles. The spectacle frames are in contact with the facial skin at all points, forming a light-tight seal so that no stray light reaches the eyes. The lenses are red filters, admitting no light below 630 nm. When these spectacles are used, adaptation can be performed in a normally lit room.

Dark Adaptation↗
PubMed1995

Evaluation of paradoxic beneficial effects of smoking in patients receiving thrombolytic therapy for acute myocardial infarction: mechanism of the "smoker's paradox" from the GUSTO-I trial, with angiographic insights. Global Utilization of Streptokinase and Tissue-Plasminogen Activator for Occluded Coronary Arteries.

OBJECTIVES: Our purpose was to evaluate the relation between smoking and the outcomes of patients receiving thrombolysis for acute myocardial infarction. BACKGROUND: A paradoxic beneficial effect has been observed in smokers with a myocardial infarction. We analyzed outcomes and baseline characteristics of 11,975 nonsmokers, 11,117 ex-smokers and 17,507 current smokers in a multinational trial of thrombolysis for acute myocardial infarction. METHODS: Patients were randomized to one of four thrombolytic protocols. An angiographic substudy in 2,431 patients evaluated reperfusion, reocclusion and ventricular function. Effects of smoking were evaluated by logistic regression analysis after adjustment for age and gender. A mortality model evaluated the simultaneous effect of baseline characteristics on the prognostic importance of smoking. These processes were performed with data from both the main trial and the angiographic substudy; then angiographic factors (coronary anatomy, patency and ejection fraction) were added to the model. RESULTS: Smokers were significantly younger by a mean of 11 years) and had less comorbidity or severe coronary artery disease than nonsmokers. Nonsmokers had significantly higher hospital and 30-day mortality rates (9.9% and 10.3%, respectively) than smokers (3.7% vs. 4%, respectively, both p < 0.001) and more in-hospital complications. The unadjusted odds ratio for 30-day mortality in nonsmokers was 3.36 (95% confidence interval [CI] 2.08 to 5.41), 1.21 (95% CI 0.71 to 2.08) after adjustment for age and gender and 1.08 (95% CI 0.59 to 1.96) after adjustment for all clinical baseline characteristics. CONCLUSIONS: Smokers receiving thrombolysis for acute myocardial infarction presented 11 years earlier than nonsmokers, which generally accounted for their better outcome. When other differences in clinical and angiographic baseline factors and therapeutic responses were evaluated, no significant difference in mortality was seen between smokers and nonsmokers.

Adult↗
PubMed1995

[Inverse stereoscopy].

Observation of three-dimensional objects with a binocular astronomical telescope results in inverse stereoscopy. Objects which are further away appear closer and vice versa. The discrepancy between accommodation and convergence can be induced in this way. Subjects whose stereoscopic vision is poor are incapable of seeing this phenomenon.

Accommodation, Ocular↗
PubMed1994

[Theoretical and clinical image properties of refractive 3-zone multifocal lenses with different distribution of far and near focus].

BACKGROUND: The optic of common multifocal IOLs (MIOLs) is effecting an even light distribution to far and near focus. New MIOL designs were developed by Jacobi to improve distance or near contrast, by favouring the far or near focus with 60-70% of the light energy. For binocular implantation, an "asymmetrical" MIOL-combination is possible with accentuation of distance focus in one eye and near focus in the other eye. METHODS: By means of an optical system described by Jacobi and Reiner "artificial eyes" with the new MIOLs were implanted in 7 young healthy subjects and contrast sensitivity was measured for distance and near. Clinical implantation was performed in 46 patients and visual acuity, contrast sensitivity, depth of focus and binocular functions were determined after 6 months. RESULTS: MIOL designs with accentuation of distance vision did not show a significant reduction of distance contrast compared with a monofocal IOL. Asymmetrical binocular implantation of the new lenses resulted in a better distance and near contrast sensitivity than implantation of MIOLs with an even light distribution. Binocular functions were not impaired. CONCLUSION: Asymmetrical implantation of the new MIOLs with uneven light distribution to far and near focus enables distance vision comparable to monofocal IOLs, but with the advantage of an increased depth of focus.

Adult↗
PubMed1993

[Properties of injectable intraocular lenses].

An aphakic eye can be corrected by injecting a liquid into the lens capsule following phacoemulsification and hardening the lens by UV irradiation. Another technique is to implant a thin casing of silicone rubber, that is then filled with liquid. The eye's resulting refraction depends strongly on the refractive index of the lens material. In either case, continuous control of the index of refraction is necessary while injecting the artificial lens material.

Humans↗
PubMed1993

["Physical eyes" for evaluating various intraocular lenses for monocular and binocular use].

We developed a "physical eye system" to evaluate visual impression after physical implantation of monofocal and multifocal intraocular lenses (IOLs). The system is constructed as two identical astronomical telescopes. The objectives imitate the cornea and behind this cornea the IOL is inserted. The image quality represents exactly the quality of the intraocular lens.

Equipment Design↗
PubMed1992

[An instrument for projecting visual perception by monofocal and bifocal intraocular lenses].

With the aid of a simple optical system similar to an astronomical telescope, images of spectacle lenses, contact lenses and intraocular lenses can be projected in front of, onto or into the eye. These optical images function like real lenses and enable their performance to be evaluated. In the case of intraocular lenses, visual perception through monofocal or bifocal lenses and teledioptric systems can be reproduced.

Equipment Design↗
PubMed1992

[Evaluation of the image quality of bi- and multifocal intraocular lenses with a new optical system].

By means of a new optical device developed by Reiner, an "optical implantation" of 6 different bi- and multifocal intraocular lenses (MIOLs) was performed in 20 young healthy subjects, and results were compared with those of a monofocal reference IOL. The following parameters were investigated: distance and near visual acuity, depth of focus and contrast sensitivity. The median of distance visual acuity was 1.0 in all IOLs with the exception of a 7-zone refractive MIOL (0.75). Near acuity without near addition was 1.0 in all MIOL models; through focus curves of all MIOLs showed an increase in depth of focus with a typical two peak course. Contrast sensitivity at high contrasts was reduced for the 7-zone-model, but contrast sensitivity at low contrasts was significantly reduced for all MIOLs, except the 2- and 3-zone refractive models.

Adult↗
PubMed1991

[Eliminating reflection of intraocular lenses].

Reflections on the refractive surfaces of intraocular lenses can be a nuisance when performing retinoscopy or refractometry. Some patients with IOLs also see reflections which disturb their vision. This article examines the conditions for coating IOLs. It also explains why conventional coating methods cannot be used for IOLs.

Humans↗