Role of the reticular formation in motor control. Study of some intrareticular mechanisms and functional properties of the reticulospinal system

Participation of the reticular formation and descending reticulospinal system in the motor control functions of the spinal cord is examined. The data indicate that the reticular formation may participate in the regulation of specific motor actions. This is shown by the results of experiments to analyze the properties of membranes of reticulospinal neurons and the principles of organization of cortico-reticular monosynaptic relays, and to the investigation of characteristics of responses of "ensembles" of reticular neurons in cats, and also by data obtained in a study of correlation of unit activity in the reticular formation with movements elaborated in rats. The functional role of differential characteristics of the reticular formation is discussed and prospects for future research into reticular membranous, neurochemical, and neuronal mechanisms as a step toward the understanding of reticular control of motor functions are described.Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Czechoslovakia. Translated from Neirofiziologiya, Vol. 16, No. 5, pp. 637–651, September–October, 1984.     

Nonspecific resistance of the organism and myxovirus inhibitors comparison of some antibacterial and antiviral mechanisms

There are three main lines of research on nonspecific resistance today: study of bactericidal and virocidal substances present in animal and human sera and tissues, study of early and delayed changes in resistance after heterologous infection or antigenic stimulation and study of cellular defence mechanisms (in particular of the reticuloendothelial system (RES) and interferon production). The authors discuss the existing situation in the classification of myxovirus inhibitors and draw attention to difficulties and errors. In the case of the beta-inhibitor of influenza viruses they draw attention to the similarity of the properties of this inhibitor and of bactericidal Gram-negative microorganisms. They cite some of the results of experiments in which they attempted to determine the origin of betainhibitors by immunizing mice, rats and guinea-pigs with their own food (mice), with their own enteric flora (guinea-pigs) and with salmonellae containing O or Vi antigen. As opposed to some of the data in the literature, they found that antibodies formed by rats immunized with influenza virus and reacting with O-or Visensitized erythrocytes were antibodies against the host's tissue present in the allantoic fluid.     

Physiology of antibiotic production in actinomycetes and some underlying control mechanisms

Some of the accumulated information on the physiology and nutritional control of antibiotic production in actinomycetes can now be related to recent discoveries in the field of actinomycete molecular biology. This review focuses on aspects of genetic and metabolic control of antibiotic biosynthesis. It surveys some well established principles in the relationship between primary and secondary metabolism, and summarizes briefly the areas where progress is being made in elucidating the molecular organization of regulatory systems underlying this relationship.     

A comparison of some properties of four strains of cherry leaf roll virus

The elm mosaic and golden elderberry strains of cherry leaf roll virus (CLRV) and a strain from cherry and from rhubarb were very similar in their host range, symptomatology and properties in vitro. However, only the rhubarb isolate infected rhubarb systemically and only the golden elderberry isolate infected Sambucus nigra systemically. Purified preparations of all strains contained isometric particles which sedimented as two nucleoprotein components with sedimentation coefficients of about 115 S and 128 S. The elm mosaic strain was the least stable in vitro and was the most difficult to purify. In plant-protection tests, one-way protection occurred between tomato ringspot virus and each of the four CLRV strains. However, whereas the elm mosaic, golden elderberry and the cherry strains protected against one another, they did not protect against infection with the rhubarb strain.     

A comparison of the properties of the cardiac beta-adrenergic receptor adenylyl cyclase system in the rat and the marmoset monkey

1. A comparison was made between adrenergic receptor binding properties and catecholamine-stimulated adenylyl cyclase activity in cardiac membrane fractions from the rat and the marmoset monkey. 2. [125I]HEAT and [125I]ICYP were used to determine respectively, the alpha- and beta-adrenergic receptor binding in cardiac membrane fractions. 3. Greatest adrenergic receptor density and degree of specific binding was evident using membranes sedimenting between 6000 and 46,000 g. 4. In rat heart, the ratio of beta- to alpha-adrenergic receptors was 57:43, while for the marmoset this ratio was 92:8. 5. Basal, isoproterenol, sodium fluoride and forskolin-stimulated adenylyl cyclase activities in the rat and marmoset monkey were investigated in several different cardiac membrane fractions. 6. The highest-fold stimulation of adenylyl cyclase activity was present in membranes sedimenting between 0 and 500 g. 7. Adenylyl cyclase activities were higher in the marmoset heart membrane preparations, however the rat heart adenylyl cyclase exhibited greater sensitivity to isoproterenol; ED50 3.8 X 10(-7) M compared with 7.5 X 10(-7) M for the marmoset. 8. Differences between rat and marmoset catecholamine-sensitive adenylyl cyclase activity were apparent when a variety of adrenergic agonists and antagonists were tested. 9. In the marmoset but not the rat, adrenergic antagonists alone stimulated basal adenylyl cyclase activity. 10. Differences in the activation of cardiac adenylyl cyclase by GTP and GMP-PNP were also evident between the rat and the marmoset monkey, particularly with regard to basal and isoproterenol-stimulated activity.     

A comparison and evaluation of some phytosociological techniques

Summary In three areas of vegetation (dune, mountain heath and salt marsh) the following phytosociological techniques have been tested and compared, using the same data: the Braun-Blanquet method; association and inverse analysis ofWilliams &Lambert; cluster analysis (agglomerative classification) based on different coefficients of similarity; and ordination (principal components analysis performed on matrices of different coefficients).The Braun-Blanquet method is considered to combine several advantages of the other methods and to be most economical in terms of efficiency (ratio of time input to information emerging).

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Zusammenfassung Auf drei verschiedenen Vegetationsflächen (Bergheide, Küstendünen und Salzwiesen) sind die folgenden pflanzensoziologischen Methoden geprüft und verglichen worden: die Methode von Braun-Blanquet; association analysis vonWilliams &Lambert (1959, 1961); Ordination (principal components analysis); und cluster analysis (Sokal &Sneath, 1963). Die letzteren beiden wurden mit verschiedenen Ähnlichkeitskoeffizienten geprüft.Auf Grund solchen Erfahrungen, zeigte sich die Braun-Blanquetische Methode leistungsfähiger als die anderen Methoden (d.h. optimale Einsicht in der Vegetation pro Arbeitsstunde). Sie vereinigte viele Vorteile der anderen Methoden.

     

A comparison of fibronectin, laminin, and galactosyltransferase adhesion mechanisms during embryonic cardiac mesenchymal cell migration in vitro

Embryonic hearts contain a homogeneous population of mesenchymal cells which migrate through an extensive extracellular matrix (ECM) to become the earliest progenitors of the cardiac valves. Since these cells normally migrate through an ECM containing several adhesion substrates, this study was undertaken to examine and compare three ECM binding mechanisms for mesenchymal cell migration in an in vitro model. Receptor mechanisms for the ECM glycoproteins fibronectin (FN) and laminin (LM) and the cell surface receptor galactosyltransferase (GalTase), which binds an uncharacterized ECM substrate, were compared. Primary cardiac explants from stage 17 chick embryos were cultured on three-dimensional collagen gels. Mesenchymal cell outgrowth was recorded every 24 hr and is reported as a percentage of control. Migration was perturbed using specific inhibitors for each of the three receptor mechanisms. These included the hexapeptide GRGDSP (300-1000 micrograms/ml), which mimics a cell binding domain of FN, the pentapeptide YIGSR (300-1000 micrograms/ml), which mimics a binding domain of LM, and alpha-lactalbumin (1-10 mg/ml), a protein modifier of GalTase activity. The functional role of these adhesion mechanisms was further tested using antibodies to avian integrin (JG22) and avian GalTase. While the FN-related peptide had no significant effect on cell migration it did produce a rounded cellular morphology. The LN-related peptide inhibited mesenchymal migration 70% and alpha-lactalbumin inhibited cell migration 50%. Antibodies against integrin and GalTase inhibited mesenchymal cell migration by 80 and 50%, respectively. The substrate for GalTase was demonstrated to be a single high molecular weight substrate which was not LM or FN. Control peptides, proteins and antibodies demonstrated the specificity of these effects. These data demonstrate that multiple adhesion mechanisms, including cell surface GalTase, are potentially functional during cardiac mesenchymal cell migration. The sensitivity of cell migration to the various inhibitors suggests that occupancy of specific ECM receptors can modulate the activity of other, unrelated, ECM adhesion mechanisms utilized by these cells.     

Bovine lactoperoxidase and its recombinant: comparison of structure and some biochemical properties

Biochemical properties of bovine lactoperoxidase isolated from milk and recombinant bovine lactoperoxidase expressed by Chinese hamster ovary cells were compared. The natural and recombinant lactoperoxidases showed the same conformational features as determined by circular dichroism (CD) measurements. The alpha-helix, beta-structure, and unordered structure contents were found to be 17. 8, 54.2, and 28.0% for the natural lactoperoxidase and 18.6, 50.1, and 31.3% for the recombinant lactoperoxidase, respectively. The microenvironments of aromatic amino acid residues in both lactoperoxidases seemed to be the same, although the CD spectral band due to the Soret band differed slightly. A difference in the pH-dependent spectral changes of absorbance at 413 nm was observed. From a pepsin hydrolysate of lactoperoxidase, a heme-binding peptide was isolated by reverse-phase HPLC and its amino acid sequence was examined.