The effect ofβ-adrenergic stimulation and blockade on the efflux of PGE1-like material from the isolated perfused rabbit heart

Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms.     

The effect of ischæmia on nucleoproteins in liver cells

Résumé Chez la souris, 24 heures après la ligature du pédicule d'un lobe hépatique, la basophilie cytoplasmique disparaît alors que les noyaux conservent une colorabilité normale par la méthode deFeulgen. Les dosages chimiques établissent que le taux de l'acide ribonucléique s'abaisse considérablement, tandis que celui de l'acide désoxyribonucléique ne subit pas de modifications appréciables. Ces phénomènes sont liés à la destruction des granules et microsomes séparables par ultracentrifugation. Une partie de ces nucléoprotéines se retrouve, après ultracentrifugations répétées, dans le liquide surnageant.     

Purification of α-ketoaldehyde dehydrogenase from the human liver and its possible significance in the control of glycation

Summary Alfa-ketoaldehyde dehydrogenase, which was extracted and purified from human livers, may act on carbonyl compounds, such as 3-deoxyglucosone, and be involved in the control of glycation (Maillard reaction) in the body.     

The effect of αB-crystallin and Hsp27 on the availability of translation initiation factors in heat-shocked cells

The mechanism of the translational thermotolerance provided by the small heat shock proteins (sHsps) αB-crystallin or Hsp27 is unknown. We show here that Hsp27, but not αB-crystallin, increased the pool of mobile stress granule-associated enhanced green fluorescent protein (EGFP)-eukaryotic translation initiation factor (eIF)4E in heat-shocked cells, as determined by fluorescence recovery after photobleaching. Hsp27 also partially prevented the sharp decrease in the pool of mobile cytoplasmic EGFP-eIF4G. sHsps did not prevent the phosphorylation of eIF2α by a heat shock, but promoted dephosphorylation during recovery. Expression of the C-terminal fragment of GADD34, which causes constitutive dephosphorylation of eIF2α, fully compensated for the stimulatory effect of αB-crystallin on protein synthesis in heat-shocked cells, but only partially for that of Hsp27. Our data show that sHsps do not prevent the inhibition of protein synthesis upon heat shock, but restore translation more rapidly by promoting the dephosphorylation of eIF2α and, in the case of Hsp27, the availability of eIF4E and eIF4G. Received 9 December 2005; received after revision 16 January 2006; accepted 23 January 2006     

The potential importance of myeloid-derived suppressor cells (MDSCs) in the pathogenesis of Alzheimer’s disease

The exact cause of Alzheimer’s disease (AD) is still unknown, but the deposition of amyloid-β (Aβ) plaques and chronic inflammation indicates that immune disturbances are involved in AD pathogenesis. Recent genetic studies have revealed that many candidate genes are expressed in both microglia and myeloid cells which infiltrate into the AD brains. Invading myeloid cells controls the functions of resident microglia in pathological conditions, such as AD pathology. AD is a neurologic disease with inflammatory component where the immune system is not able to eliminate the perpetrator, while, concurrently, it should prevent neuronal injuries induced by inflammation. Recent studies have indicated that AD brains are an immunosuppressive microenvironment, e.g., microglial cells are hyporesponsive to Aβ deposits and anti-inflammatory cytokines enhance Aβ deposition. Immunosuppression is a common element in pathological disorders involving chronic inflammation. Studies on cancer-associated inflammation have demonstrated that myeloid-derived suppressor cells (MDSCs) have a crucial role in the immune escape of tumor cells. Immunosuppression is not limited to tumors, since MDSCs can be recruited into chronically inflamed tissues where inflammatory mediators enhance the proliferation and activation of MDSCs. AD brains express a range of chemokines and cytokines which could recruit and expand MDSCs in inflamed AD brains and thus generate an immunosuppressive microenvironment. Several neuroinflammatory disorders, e.g., the early phase of AD pathology, have been associated with an increase in the level of circulating MDSCs. We will elucidate the immunosuppressive armament of MDSCs and present evidences in support of the crucial role of MDSCs in the pathogenesis of AD.     

The effects of vitamin A nutritional status on microsomal lipid peroxidation and α-tocopherol level in rat liver

Summary In vitamin A-deficient rats, liver glutathione peroxidase activity was decreased, -tocopherol content was strongly enhanced, but microsomal liquid peroxidation remained unchanged.     

The quest for the size of the universe in early relativistic cosmology (1917–1930)

Before the discovery of the expanding universe, one of the challenges faced in early relativistic cosmology was the determination of the finite and constant curvature radius of space-time by using astronomical observations. Great interest in this specific question was shown by de Sitter, Silberstein, and Lundmark. Their ideas and methods for measuring the cosmic curvature radius, at that time interpreted as equivalent to the size of the universe, contributed to the development of the empirical approach to relativistic cosmology. Their works are a noteworthy example of the efforts made by modern cosmologists toward the understanding of the universe as a whole, its properties, and its content.     

Cocarcinogens of the diterpene ester type from Croton flavens L. and esophageal cancer in Cura?ao

From the roots of Croton flavens L., 3 highly irritant and tumor promoting Croton factors F1--F3 and the corresponding 3 cryptic Croton factors F'1--F'3 were isolated and characterized as novel esters of 16-hydroxy- and 4-deoxy-16-hydroxyphorbol, respectively. These findings suggest that tumor promoters of the phorbol ester type, ingested through the widespread and frequent use of Croton flavens according to local habits, may be causally related to the well recognized high rate of esophageal cancer on Cura?ao.     

The platypus in Edinburgh: Robert Jameson,Robert Knox and the place of the Ornithorhynchus in nature, 1821–24

The duck-billed platypus, or Ornithorhynchus, was the subject of an intense debate among natural historians in the late eighteenth and early nineteenth centuries. Its paradoxical mixture of mammalian, avian and reptilian characteristics made it something of a taxonomic conundrum. In the early 1820s Robert Jameson (1774–1854), the professor of natural history at the University of Edinburgh and the curator of the University's natural history museum, was able to acquire three valuable specimens of this species. He passed one of these on to the anatomist Robert Knox (1791–1862), who dissected the animal and presented his results in a series of papers to the Wernerian Natural History Society, which later published them in its Memoirs. This paper takes Jameson's platypus as a case study on how natural history specimens were used to create and contest knowledge of the natural world in the early nineteenth century, at a time when interpretations of the relationships between animal taxa were in a state of flux. It shows how Jameson used his possession of this interesting specimen to provide a valuable opportunity for his protégé Knox while also helping to consolidate his own position as a key figure in early nineteenth-century natural history.     

The presence of β-phenylethylamine,p-tyramine,m-tyramine and tryptamine in ganglia and foot muscle of the garden snail (Helix aspersa)

Summary The concentrations of -phenylethylamine,p-tyramine,m-tyramine,m-octopamine and tryptamine in the ganglia or foot muscle ofHelix aspersa range from <0.6 to 11 ng/g.p-Octopamine levels are higher in ganglia (327 ng/g) than in foot muscle (4.1 ng/g). Dopamine and 5-hydroxytryptamine range from 840 to 2710 ng/g while their acid metabolites, 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylacetic acid and 5-hydroxyindoleacetic acid range from <20 to 130 ng/g.Acknowledgments. We thank Dr A.A. Boulton for helpful discus sion, Dr D.A. Durden for supervising the mass spectrometric analyses, Dr B.A. Davis for the synthesis of the deuterated standards, G.H. Wheatley, E.P. Zarycki and M. Mizuno for expert technical assistance, and Saskatchewan Health and the MRC of Canada for providing financial support.     

The early years of the Lycée and the Lycée des Arts. A chapter in the lives of A. L. Lavoisier and A. F. de Fourcroy

The first professors at the newly-established London University (later University College London) were appointed in 1827, but a chair in geology was not created there until 1841. In the intervening years, teaching in geology and palaeontology was included in other natural science courses. Early in 1831, John Phillips, keeper of the Yorkshire Museum at York, was prompted to give a formal course of geological lectures and subsequently he was informally offered the professorship, which he declined.     

A dialyzable factor from plasma responsible for the “viscous metamorphosis” of the blood platelets. Its role in clot retraction and haemostasis

Zusammenfassung Die visköse Metamorphose der Blutplättchen ist ein von der Fibrinbildung unabhängiger Prozess, der durch Thrombin und einen thermostabilen, dialysierbaren Faktor aus Plasma oder Serum ausgelöst wird. Das unter diesen Bedingungen aus den zerfallenden Plättchen austretende Material kontrahiert sich spontan. Dies erklärt die Gerinnselretraktion, bei der dem Fibrin folglich eine völlig passive Rolle zukommt.

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Supported by grants from the Swiss National Foundation for Scientific Research and the F. Hoffmann-La Roche Foundation.     

Reading Gauss in the Computer Age: On the U.S. Reception of Gauss’s Number Theoretical Work (1938–1989)

C.F Gauss’s computational work in number theory attracted renewed interest in the twentieth century due to, on the one hand, the edition of Gauss’s Werke, and, on the other hand, the birth of the digital electronic computer. The involvement of the U.S. American mathematicians Derrick Henry Lehmer and Daniel Shanks with Gauss’s work is analysed, especially their continuation of work on topics as arccotangents, factors of n ² + a ², composition of binary quadratic forms. In general, this strand in Gauss’s reception is part of a more general phenomenon, i.e. the influence of the computer on mathematics and one of its effects, the reappraisal of mathematical exploration. I would like to thank the Alexander-von-Humboldt-Stiftung for funding this research. For their comments I would like to thank Catherine Goldstein, Norbert Schappacher and especially John Brillhart.     

The union of arts and sciences in the eighteenth century: Lorenz Spengler (1720–1807), artistic turner and natural scientist

The life and career of Lorenz Spengler (1720–1807) provides evidence to support the view that the eighteenth century was a period when there was a fruitful interrelationship between the arts, crafts, and sciences in the courts and capitals of Europe. Spengler was trained as a turner, and was appointed teacher of ornamental turning to the Danish royal family and turner of the court in 1745. Even in the early years of his artistic career Spengler was interested in electricity and its role in healing, and he became an avid collector of shells and naturalia. Over the years, Spengler's interests turned more to the natural sciences, and in 1771 he was appointed director of the King's Kunstkammer. Only by considering both aspects of Spengler's career can his scientific activities be placed in their proper historical context.     

A stepwise model of polyreactivity of the T cell antigen-receptor (TCR): its impact on the self–nonself discrimination and on related observations (receptor editing,anergy, dual receptor cells)

The existence of antigen-receptors, BCR, and T cell antigen-receptors, that are “polyreactive”, necessitates a rethinking of its effect on two problems faced by the “adaptive” immune system: the self (S)–nonself (NS) discrimination and the determination of effector class. Here, we will concentrate on the impact of polyreactivity on the S–NS discrimination. The anti-S cells interacting with S (i.e., responding to Signal 1) are on the pathway to inactivation. Before irreversibility sets in, these cells can be activated by a second signal (Signal 2) from an effector T-helper (eTh). As these polyreactive anti-S cells express anti-NS specificities, they can be activated by recognition of NS-epitopes in the host’s normal immunogenic load with the potential to result in autoimmunity. This problem is delineated using a discrete structural model, the corollaries of which are: (1) a two-step pathway for the purging of anti-S cells (i.e., the S–NS discrimination), and (2) defensible contexts within which to view the phenomena of receptor editing, anergy, and dual receptor cells.