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G Rainer

Publications and source records attributed to G Rainer.

43 records · Page 3Linked to original sources
PubMed1997

Reproducibility and sensitivity of scanning laser Doppler flowmetry during graded changes in PO2.

AIMS/BACKGROUND: Recently a commercially available scanning laser Doppler flowmeter has been produced, which provides two dimensional maps of the retinal perfusion. The aim of the present study was to investigate the reproducibility and the sensitivity of these measurements. METHODS: 16 healthy subjects were randomised to inhale different gas mixtures of oxygen and nitrogen in a double blind crossover study. The following gas mixtures of oxygen and nitrogen were administered: 100% oxygen + 0% nitrogen, 80% oxygen + 20% nitrogen, 60% oxygen + 40% nitrogen, 40% oxygen + 60% nitrogen, 30% oxygen + 70% nitrogen, 20% oxygen + 80% nitrogen, 15% oxygen + 85% nitrogen, and 10% oxygen + 90% nitrogen. Retinal haemodynamic variables and systemic haemodynamics were measured during all inhalation periods. Recordings under resting conditions were performed three times to calculate intraclass coefficients. RESULTS: In two subjects we did not obtain technically adequate results. A dose dependent change in retinal blood flow during graded oxygen breathing was observed (p < 0.001). During 100% oxygen breathing blood flow decrease was between 29% and 33%, whereas blood flow increase was between 28% and 33% during inhalation of 10% oxygen + 90% nitrogen. CONCLUSIONS: Scanning laser Doppler flowmetry has an acceptable reproducibility and is appropriate for description of the effect of graded changes in PO2 on retinal haemodynamics. The main problems with the system are the large zero offset, the fixation during retinal scanning, and the neglect of blood flow changes during the cardiac cycle.

Adult↗
PubMed1992

(H+,K+)-ATPase inhibiting 2-[(2-pyridylmethyl)sulfinyl]benzimidazoles. 4. A novel series of dimethoxypyridyl-substituted inhibitors with enhanced selectivity. The selection of pantoprazole as a clinical candidate.

[(Pyridylmethyl)sulfinyl]benzimidazoles 1 (PSBs) are a class of highly potent antisecretory (H+,K+)-ATPase inhibitors which need to be activated by acid to form their active principle, the cyclic sulfenamide 4. Selective inhibitors of the (H+,K+)-ATPase in vivo give rise to the nonselective thiophile 4 solely at low pH, thus avoiding interaction with other thiol groups in the body. The propensity to undergo the acid-catalyzed transformation is dependent on the nucleophilic/electrophilic properties of the functional groups involved in the formation of 2 since this step is both rate-determining and pH-dependent. The aim of this study was to identify compounds with high (H+,K+)-ATPase inhibitory activity in stimulated gastric glands possessing acidic pH, but low reactivity (high chemical stability) at neutral pH as reflected by in vitro (Na+,K+)-ATPase inhibitory activity. The critical influence of substituents flanking the pyridine 4-methoxy substituent present in all derivatives was carefully studied. The introduction of a 3-methoxy group gave inhibitors possessing a combination of high potency, similar to omeprazole and lansoprazole, but increased stability. As a result of these studies, compound 1a (INN pantoprazole) was selected as a candidate drug and is currently undergoing phase III clinical studies.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1981

[Synthesis and physico-chemical properties of lonazolac-Ca, a new antiphlogistic/antirheumatic agent].

Calcium-[3-(p-chlorophenyl)-1-phenylpyrazole-4]-acetate (Lonazolac-Ca, active principle of Irritren) is a new antiinflammatory/antirheumatic agent whose synthesis and physico-chemical properties are described. The physical parameters measured (pKa, partition coefficient P, saturation concentration Cs, surface activity, protein binding) are held against the corresponding values of indomethacin, diclofenac, and phenylbutazone. The size of the permeability coefficient PM of the passive transport through artificial phospholipid collodion membranes as well as the invasion curves calculated from PM indicate a good absorption of lonazolac in man.

Acetates↗
PubMedDate not supplied

Improved algorithm for statistical batch-by-batch analysis of corneal topographic data.

PURPOSE: To describe an improved algorithm for topographic batch-by-batch analysis and evaluate the effect of artifact correction on the reproducibility of topographic records. SETTING: University Eye Hospital Vienna, Austria. METHODS: We twice examined 22 eyes of 22 patients (volunteers) using the TMS-1 computer-assisted videokeratoscope (Computed Anatomy, Inc.). Entry criteria were age more than 60 years and lack of corneal pathology. A batch-by-batch analysis of the paired differences was performed. The software consisted of special macro functions for a programmable computer database to eliminate small local artifacts, as well as rotate data, produce mirror images, calculate averaged differences for an entire group, and reduce data to 225 areas in 7 concentric rings. The reduced set of data was used for statistical analysis and correction of defocus artifacts. Reproducibility was evaluated by calculating the absolute deviations between the areas of paired measurements. RESULTS: The absolute deviations were below 0.9 diopter (D) in over 50% of the areas in 90% of the patients with the uncorrected data; after correction for local artifacts, defocus artifacts, and both local and defocus artifacts, these values were 0.9 D, 0.8 D, and 0.5 D, respectively. Absolute deviations were above 1.0 D in 10% of the patients in 66, 40, 29, and 0 of 225 areas, respectively. CONCLUSION: Correction for both local and defocus artifacts yielded a two-fold improvement in the reproducibility of topographic records.

Aged↗
PubMedDate not supplied

Corneal topographic changes after frown and straight sclerocorneal incisions.

PURPOSE: To compare the corneal topographic changes following cataract surgery with two types of sclerocorneal tunnel incisions for implantation of 6.0 mm optic poly(methyl methacrylate) intraocular lenses. SETTING: University Eye Hospital, Vienna, Austria. METHODS: This prospective, unmasked, and unrandomized study comprised 48 otherwise healthy eyes scheduled for cataract surgery. A 4.5 mm sutureless frown incision was made in 22 eyes and a 6.0 mm straight sclerocorneal incision with a horizontal 10-0 nylon infinity suture in 26 eyes. Preoperatively and 1 week and 1 and 3 months postoperatively, corneal topography was recorded by the TMS-1 computer-assisted videokeratoscope (Computed Anatomy, Inc.). The data were evaluated by batch-by-batch analyses of the paired differences between the records. The significance of topographic changes was calculated by paired Wilcoxon tests; group comparisons were made using Wilcoxon tests. RESULTS: In both groups, horizontal steepening and lower corneal flattening were consistently 0.4 diopter (D). Upper peripheral corneal flattening at 1 week and 1 and 3 months postoperatively was 0.7, 0.7, and 0.7 D, respectively, in the straight-incision group and 0.7, 0.4, and 0.3 D, respectively, in the frown-incision group. Vertical flattening and horizontal steepening were significant in both groups (P < .01). Group comparisons revealed significant differences in only 15 of 225 areas (P < .05). CONCLUSION: There were no major differences between the two incision groups in surgically induced topographic changes.

Aged↗