Is stepwise sarcomere shortening an artefact?

A report in 1977 raised the intriguing possibility that sarcomere shortening in muscle may occur in a stepwise fashion, in which episodes of shortening are interrupted by periods of little or no movement. This was taken by its authors to imply the synchronous activity of cross-bridges over a large volume of tissue-behaviour which cannot easily be reconciled with commonly accepted views of muscle contraction. Stepwise shortening has also been reported recently in relaxed muscle fibres on which length changes were externally imposed, and that system has allowed us to define more rigorously the circumstances in which stepwise shortening is observed. Here we report a high correlation between the frequency of 'steps' or 'pauses' and the translation velocity of the fibre past the measuring system, suggesting that stepwise shortening is not a physiological property of muscle but an instrumentation artefact.     

Nachweis von Reflex-Bluten bei Lampyriden (Coleoptera) mit Hilfe der „Tracer”-Methode

Summary The very short time (5–9 min) between injection of radiophosphorous into the hemolymph of adult fireflies (Lampyridae) and outflow of radioactive droplets after irritation demonstrates with certainty that reflex-bleeding is involved. Labelling the secretions of dermal glands would require much more time (several h or even 1 day.

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Institut für Angewandte Zoologie der Universität Bonn. Die Untersuchungen wurden 1972 während eines Aufenthaltes vonW. J. Kloft als Visiting Professor an der University of Florida durchgeführt.     

Lack of effect of dihydroergotamine on endothelial and smooth muscle cell proliferation and endothelial cell prostanoid production

The most important effect of dihydroergotamine is venoconstriction, but certain metabolic effects and changes in vessel prostanoid activity have also been suggested. In this study endothelial cell production of 6-keto PGF1 alpha and TxB2 was quantitated in vitro. No evidence of altered prostanoid production was noted after incubation with dihydroergotamine (exposure ranging from 5 x 10(-3) to 5 x 10(-7) g/l). Similarly, no effect of dihydroergotamine on the growth rates of endothelial cells or smooth muscle cells in vitro was documented.     

Genetic and pharmacological models of cholinergic supersensitivity and affective disorders

Increased muscarinic sensitivity has been associated with altered hormonal states (hypothyroidism and hyperadrenocorticism), chronic administration of muscarinic antagonists or antidepressants with muscarinic actions, selective breeding for anticholinesterase sensitivity, and certain inbred strains of rats and mice. Thus, both genetic and environmental factors may influence muscarinic receptor sensitivity. The reasonably detailed studies on the selectively-bred rats have revealed that the Flinders Sensitive Line (FSL) rats weigh less, are less active, are more sensitive to muscarinic agonists and to stressors, and have higher concentrations of hippocampal and striatal muscarinic receptors than 'normal', or the selectively-bred, Flinders Resistant Line (FRL) rats. Thus, there are a number of parallels between FSL rats and depressed humans. The FSL rats may be the first animal model of depression to mimic the actual trait of depression, and not just the state.     

Hybridization histochemistry

Summary The location of gene expression by hybridization histochemistry is being applied in many areas of research and diagnosis. The aim of this technique is to detect specific mRNA in cells and tissues by hybridization with a complementary DNA or RNA probe. Requirements for optimal specificity, sensitivity, resolution and speed of detection may not all be encompassed in one simple technique suitable for all applications, thus appropriate procedures should be selected for specific objectives. With reference to published procedures and our own extensive experience, we have evaluated fixatives, probes, labels and other aspects of the technique critical to the preservation and hybridization in situ of mRNA and detection and quantition of hybrids.     

Applications of time-series analysis in accounting: A review

This paper reviews research that makes use of one of the most popular forecasting methods applied in accounting: time-series analysis using the Box-Jenkins methodology. It organizes the research in the area, surveys recent applications of time-series analysis in accounting, and discusses the potential for the methodology in addressing future research issues. The emphasis is on those aspects of the accounting system that possibly cause difficulties in applying time-series methods in accounting.