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T Reuter

Publications and source records attributed to T Reuter.

59 records · Page 4Linked to original sources
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The effect of coronary flow restriction on the viability of porcine myocardium.

The effect of a prolonged (3 hours) defined coronary flow restriction on early (30 minutes) and late (24 hours) reperfusability and survival of the myocardium was studied in a closed-chest pig model. Coronary blood flow (CBF) was restricted to 51 +/- 4% (moderate flow restriction) and 36 +/- 6% (severe flow restriction) of preexisting resting flow values. Regional determination of the restricted CBF after severe flow restriction showed the anticipated extension of the ischemic area from endocardial to epicardial layers and to the lateral border zone. Upon early reperfusion a hyperemic effect was observed, which reflected the preceding degree of underperfusion. The maximal hyperemic effect was found in samples with CBF restriction to 38% of the control flow values. Twenty-four hours after blood flow restitution the hyperemic effect had disappeared. At this time control flow values had not returned, where previous CBF restriction had exceeded 50%. The amount of infarcted tissue in the area supplied by the left circumflex artery was 5.7% after moderate, and 31.6% after severe flow restriction. Morphologically the infarcted myocardium consisted of disseminated necrosis after moderate, and of confluent necrosis after severe flow restriction. At flow restriction exceeding 50%, the chances of reestablishing perfusion and thus salvaging the myocardium appear minimal.

Animals↗
PubMedDate not supplied

In search of the visual pigment template.

Absorbance spectra were recorded by microspectrophotometry from 39 different rod and cone types representing amphibians. reptiles, and fishes, with A1- or A2-based visual pigments and lambdamax ranging from 357 to 620 nm. The purpose was to investigate accuracy limits of putative universal templates for visual pigment absorbance spectra, and if possible to amend the templates to overcome the limitations. It was found that (1) the absorbance spectrum of frog rhodopsin extract very precisely parallels that of rod outer segments from the same individual, with only a slight hypsochromic shift in lambdamax, hence templates based on extracts are valid for absorbance in situ: (2) a template based on the bovine rhodopsin extract data of Partridge and De Grip (1991) describes the absorbance of amphibian rod outer segments excellently, contrary to recent electrophysiological results; (3) the lambdamax/lambda invariance of spectral shape fails for A1 pigments with small lambdamax and for A2 pigments with large lambdamax, but the deviations are systematic and can be readily incorporated into, for example, the Lamb (1995) template. We thus propose modified templates for the main "alpha-band" of A1 and A2 pigments and show that these describe both absorbance and spectral sensitivities of photoreceptors over the whole range of lambdamax. Subtraction of the alpha-band from the full absorbance spectrum leaves a "beta-band" described by a lambdamax-dependent Gaussian. We conclude that the idea of universal templates (one for A1- and one for A2-based visual pigments) remains valid and useful at the present level of accuracy of data on photoreceptor absorbance and sensitivity. The sum of our expressions for the alpha- and beta-band gives a good description for visual pigment spectra with lambdamax > 350 nm.

Animals↗