Peptido-aminobenzophenones-novel latentiated benzo-1,4-diazepines

Summary It has been shown that cleavage of the N-terminal L-amino acids of a novel series of dipeptide derivatives of 2-aminobenzophenones occurs readily in vivo to give benzo-1,4-diazepines. Such compounds may serve as useful pro-drug forms of minor tranquillizers such as Valium^®.     

Tracing the use of torture: electrically induced calcification of collagen in pig skin

Reports of the use of electrical torture are usually denied, so that there is an urgent need of diagnostic methods to distinguish the consequences of electrical torture from other superficial injuries. The 'electrical group' of Anti-Torture Research (ATR) has accordingly studied the possibility of distinguishing between the sequelae of electrical and heat injury. Among the reported differences of the two types of injuries is the occurrence in epidermis, vessel walls and sweat glands of vesicular nuclei exclusively in electrically injured skin. On the basis of experiments with anaesthetized pigs, we now report that the late sequelae of electrical injury appear to include the deposition of calcium salts beneath the area of an electrical cathode.     

High resolution structure of the RNA duplex [U(U-A)6A]2

RNA is involved in many biological functions, ranging from information storage and transfer to the catalysis of reactions involving both nucleic acids and proteins. Previous crystallographic studies on RNA oligomeric chains provide only averaged structures or information limited in resolution. The oligomer [U(U-A)6A]2 was chosen for the study of protein-RNA interactions in viruses. Its size and base composition mimic portions of the genomic RNA in alfalfa mosaic virus that bind to the amino terminus of the viral subunit. The actual sequence was designed to guarantee the formation of a single species of duplex and to facilitate the production of the pure oligomer in large quantities. The molecular structure, derived from the 2.25 A resolution X-ray diffraction data, allows the most detailed analysis of an A-RNA helix reported to date. Two kinks are observed that divide the duplex into three blocks, each close to a canonical A-helical conformation. A few intermolecular hydrogen bonds involving 2'-hydroxyl groups stabilize this peculiar conformation of the RNA, which may be related to the temperature used for the crystallization (35 degrees C). The structure demonstrates both the plasticity of the RNA molecule and the role of the 2'-hydroxyl groups in intermolecular interactions.     

Stimulation of multipotential, erythroid and other murine haematopoietic progenitor cells by adherent cell lines in the absence of detectable multi-CSF (IL-3)

It is well established that murine multipotential and committed erythroid progenitor cells require the presence of a glycoprotein, termed multi-CSF (multi-colony-stimulating factor, IL-3) for clonal proliferation and differentiation in vitro. The initial proliferation of these cells can also be stimulated by two other glycoproteins, granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), although continued proliferation and differentiation requires the subsequent presence of multi-CSF. Here we report the stimulation of multipotential, erythroid and other haematopoietic progenitor cells by a number of adherent cell lines including a cloned bone marrow cell line (B.Ad). The positive cell lines, as feeder layers, exhibit colony-stimulating, erythropoietin-like and burst-promoting (BPA) activities. Optimal erythropoietic stimulation by the B.Ad line requires close cell-cell contact. The cell lines also support the in vitro clonal growth of multipotential colony-forming cells and progenitors of six other haematopoietic lineages. The biological activities observed seem not to be mediated by known multipotential or erythroid colony-stimulating factors (multi-CSF, IL-3, MCGF, HCGF, PSF, BPA).     

Erythropoietic response to isomeres of triiodothyronine

Zusammenfassung Verabreichung vond-, wie auch vonl-Triiodothyrosin erzeugt eine ähnliche Vermehrung der Erythropoiesis in nephroektomierten Ratten, wie bei der Messung der Radioeiseninkorporation durch Erythrozyten (18 h nach Injektion von radioaktivem Eisencitrat). Es ergab sich weiter, dassd- undl-Thyrosin, im Unterschied zu Erythropoieten, die reticulozytose Eisenassimilation in vitro vermehrte. Danach scheinen verschiedene Mechanismen bei der Stimulation der Erythropoiesis durch Erythropoieten und Triiodothyronin im Spiele zu sein.     

Experimental manipulation of a contact guidance system in amphibian gastrulation by mechanical tension

Contact guidance has been implied in various morphogenetic movements including neural crest cell migration, primordial germ cell migration and guidance of axonal growth cone. In urodele gastrulae, we reported the presence of an aligned network of extracellular fibrils on the inside of the ectodermal layer and suggested that it guides the migration of the presumptive mesodermal cells from the blastopore towards the animal pole. We also reported in vitro experiments in which the fibril network of the ectodermal layer was transferred onto the surface of a coverslip. Dissociated mesodermal cells attach to and locomote actively on such conditioned surfaces in an oriented fashion along the blastopore-animal pole axis (bp-ap axis) of the ectodermal layer that conditioned the surface. Recent reports suggest that these fibrils contain fibronectin. We now report that the fibril network on the conditioned surface can be artificially aligned in any orientation by exerting mechanical tension on the ectodermal layer during the conditioning. Such prepared surfaces cause cell movements aligned along the tension axis, even when the tension axis is perpendicular to the natural axis of alignment along the bp-ap axis. These results suggest that the extracellular matrix fibrils aligned by the mechanical stress that arises in embryos during development can orient cell migration by the contact guidance, in a similar manner to that reported in the collagen gel and fibroblasts system.     

Selection for resistance toBacillus thuringiensis δ-endotoxin in an insect cell line (Choristoneura fumiferana)

Summary A cell line of the spruce budworm (FPMI-CF1) consists of a mixed population of cells that possess variable sensitivity to -endotoxin from crystals ofBacillus thuringiensis. A cell strain was selected from FPMI-CF1 which was resistant to the entomocidal protein extracted fromB. thuringiensis crystals. The resistant character was unstable, however, and could not be maintained in the absence of toxin during growth.The author wishes to thank S.S. Sohi (Forest Pest Management Institute, Canadian Forestry Service, Sault Ste. Marie, Ontario, Canada) for theC.fumiferana cell line, and L.I. Davidson (USDA) for his able technical assistance.