Parametric and Nonparametric Analyses of Repeated Ordinal Categorical Data

We compare two models for the analysis of repeated ordinal categorical data: the classical parametric model for means of scores assigned to the categories of the response variable and a nonparametric model based on relative effects derived from the marginal distribution functions of the response. An example in the field of Dentistry is used to illustrate and to compare the models. We also consider a simulation study to evaluate the type‐I error rates and the power of tests under both models in a balanced design setup. The simulation results suggest that both approaches behave similarly for equally spaced scores but may perform differently otherwise. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of polyadenylated RNA from brain synaptosomes and mitochondria

We have isolated RNA from sheep brain synaptosomes and mitochondria separated by an aqueous two-phase system composed of dextran and poly(ethylene glycol). RNA was fractionated through oligo(dT)-cellulose columns and analyzed by electrophoresis through agarose slab gels containing methylmercuric hydroxide and stained with ethidium bromide. The electrophoretic patterns of the poly(A)-containing RNA fraction from synaptosomes and mitochondria are very similar although some high molecular weight RNA species, clearly visible in the synaptosomal fraction, are scarcely detected in the mitochondrial preparations. The electrophoretic analysis of a cleaner RNA preparation from digitonin-treated free mitochondria (mitoplasts) showed that all the poly (A)-RNA species of the synaptosomal preparation are also present in mitoplast. These results strongly suggest that all the discrete poly(A)-RNA species identified in brain synaptosomes are of mitochondrial origin.     

Subcellular localization and glycoprotein nature of the invertase from the fission yeast Schizosaccharomyces pombe

The subcellular localization of the enzyme invertase in Schizosaccharomyces pombe cells, both repressed and derepressed for synthesis of the enzyme, was studied. Most of the invertase was found to be located outside the plasma membrane and only a small percentage was found to be associated to membranes. A substantial portion of the external enzyme remained firmly bound to cell-wall material.All of the invertase recovered in soluble form from cellular extracts reacted with concanavalin A and with the lectin from Bandeiraea simplicifolia seeds, indicating the presence in the enzyme of a carbohydrate moiety which probably contains terminal mannosyl (or structurally related) and galactosyl residues.The possibility of the presence of two different forms of invertase in S. pombe was considered. An intracellular, soluble form of invertase, devoid of carbohydrate, similar to the small invertase of the budding yeast Saccharomyces cerevisiae, was not found in S. pombe. However, the Michaelis constant for sucrose of the enzyme present in repressed cells was smaller than that of the invertase synthesized under derepressing conditions, although this difference could also be the result of a different pattern of glycosylation of the invertase synthesized under different growth conditions.     

Tubulin and tubulin-colchicine complex bind to brain microsomal membrane in vitro

Brain tubulin was labeled in vitro by post-translational incorporation of [14C]-tyrosine or in vivo by intra-cranial injection of [3H]-leucine. The labeled protein was purified by ion-exchange chromatography. After incubating at 37 degrees C with a microsomal membrane preparation from rat brain, part of the labeled soluble tubulin became sedimentable at high-speed centrifugation. This was independent of the native configuration of tubulin, the state of tyrosination of the COOH-terminus, or the presence of 100 microM colchicine in the mixture. In addition, the double-labeled tubulin-colchicine complex obtained from the binding of [3H]-colchicine to [14C]-tyrosinated tubulin, bound to the membrane preparation to the same extent as [14C]-tyrosinated tubulin. The data show that either tubulin or the complex resulting from its binding to colchicine distributed between the soluble and the membrane fractions when mixed at 37 degrees C with a microsome preparation. Seemingly, the site for colchicine binding to tubulin needs not to be free for the protein-membrane association.     

Structural organization of the normal and anoxic heart of Scyllium stellare

Summary The general and ultrastructural organization of the heart of the elasmobranch, Scyllium stellare, was studied in normal and in anoxic animals. The rich coronary supply was revealed three-dimensionally by the use of corrosion casts, showing a thebesian system of coronary arterioles and capillaries in the thin, outer compact layer as well as in the predominant, inner spongy layer of trabeculae.Only the sinus venosus received a neuronal input of large bundles of granule-containing axons terminating at fenestrated regions of the endocardium and suggesting a neurohormonal function.A simple, tubular sarcoplasmic reticulum with flattened junctional cisternae was present in myocardial cells of 1–5 m diameter, which contained one or two bundles of myofibrils. The latter were closely apposed to the inner aspect of the plasmalemma. Mitochondria were located centrally in the cells, which were joined by unfolded desmosomes involving Z-band material.Long periods of anoxia were tolerated without loss of heart function, but at the expense of cytoplasmic glycogen. Lipid granules were abundant in all layers and chambers, notably in animals prepared in the summer. The lipid granules displayed a marked increase in electron density when the heart was incubated in a buffered oxalate solution prior to fixation. A glycogen-sparing effect of the lipids during anoxia was observed.     

Phytochrome in etiolated annual rye

Summary During a seven-fold increase in length the content of the coleoptile in photoreversible phytochrome increased four-fold and that of the primary leaf nine-fold. The phytochrome content, during growth, expressed on a fresh- or dry-weight basis did not vary greatly for either organ. Phytochrome per mg dry weight (OD⁷³⁰/mg=0.5) was nearly the same in the leaf as in the coleoptile. Coleoptiles studied had a constant DNA content of 4.1 g per organ. DNA content of the leaf increased with age. Phytochrome per DNA was much higher in the coleoptile than in the primary leaf and increased with growth in each of these organs. Thus, there was not a constant amount of phytochrome per cell in either tissue with increasing age and there was not the same amount of phytochrome per cell in the coleoptile as in the primary leaf at any age.This work was supported in part by U.S. Atomic Energy Commission Contract No. AT (30-I)2373.     

Aortic aneurysm in a Cebus apella monkey with experimentally induced atherosclerosis

The sudden death of a Cebus apella female (>19 years old) on an experimental hyperlipidic diet during three years is described. The gross lesions were hemothorax, atherosclerotic plaques in the aortic curve, and an aneurysm in the ascending aorta. Histologically, an enlargement of the intima in the ascending aorta with hyalinization and a thrombus were observed. The media was thinned and showed sclerosis and hemorrhage extending to the tunica adventicia.