A review of the chemical induction of neoplasms in amphibia

Résumé Ce rapport analyse et résume les résultats des travaux de différents auteurs sur la possibilité d'induire des tumeurs par des substances chimiques chez les Amphibiens.Les substances cancérigènes peuvent, dans les cas positifs: (1) induire des tumeurs caractérisées, (2) augmenter l'incidence des tumeurs spontanées, (3) produire des hyperplasies de l'épithélium cutané.On peut se demander si les hyperplasies observés sont une réaction spécifique aux substances cancérigènes et sont réellement de nature néoplasique.On peut s'étonner, aussi, que les Amphibiens dont le pouvoir de régénération est élevé et dont le développement embryonnaire, la vie larvaire et la métamorphose sont bien connus, n'aient pas davantage été utilisés dans létude du cancer.     

A comparative study of the innervation of the choroid plexus in amphibia

Summary The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.Acknowledgment. The authors are very grateful to Prof. T. Wasano (Professor emeritus of Kyushu University) for his encouragement and advice during the course of the present work.     

A comparative study of the innervation of the choroid plexus in amphibia

The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.     

The embryonic origin of the intrinsic limb musculature in amphibia,salientia

Zusammenfassung Das Blastem, welches sich zur freien, hinteren Gliedmassenmuskulatur entwickelt, stammt bei Anuren von parietalem Mesoderm und von Ursegmenten ab. Das Vorderbein-Mesoderm dagegen ist ausschliesslich parietal. Diese Feststellungen werden durch Befunde an transplantierten Beinknospen und durch Markierungsversuche mit Kohlepartikeln gestützt.Die Brauchbarkeit des Kohlemarkierungs-Verfahrens wurde speziell in ihrer Anwendung auf die Feststellung der Wanderrouten von Muskelzellen geprüft.     

The effect of cobra venom factor (CVF) activation of the complement cascade on leukocyte circadian variation in the rat

Summary Administration of cobra venom factor (CVF) at different time periods over a 24-h-period produced a leukocytic response which varied according to the time of day the factor was given. The resulting leukocytic circadian rhythm was achieved by a marked variation and increase in the neutrophil population.This study was supported by U. S. P. H. S. Grant No. HL 16769 and Grant No. AI 09169.     

A human calcitonin-like molecule in the ultimobranchial body of the amphibia (Rana pipiens)

Summary As assessed by radioimmunoassay, and high performance liquid chromatography (HPLC), frog ultimobranchial calcitonin was found to be similar to synthetic human calcitonin but completely different from synthetic salmon calcitonin.Acknowledgments. This work was supported in parts by grants from the Medical Research Council, Wellcome Trust, Spanish Ministry of Universities and Egyptian Ministry of High Education.     

The murine complement regulator Crry: new insights into the immunobiology of complement regulation

Complement has an important role in inflammation and in the normal function of the immune system. Activated complement fragments have the capacity to bind and damage self-tissues. Cells from vertebrates express on their surface regulators of complement activation that protect them from the deleterious effects of cell-bound complement fragments. Abnormalities in these regulators of complement activation may participate in the pathogenesis of autoimmune diseases and inflammatory disorders. Murine Crry is one of these regulators that inhibits the activation of the third component of complement and protects self-tissues from complement-mediated damage. Experimental work on Crry has increased our understanding of the immunobiology of complement regulation and the potential role of complement and complement inhibitors in the development and treatment of human diseases. Received 13 June 2001; received after revision 12 July 2001; accepted 9 August 2001     

A comparative study of the correlations existing in the ratio between nucleolar dimensions and number of nucleolini in the oocytes of amphibia

Riassunto Le indagini statistiche effettuate sui nucleoli degli ovociti diRana esculenta, Discoglossus pictus eTriturus cristatus hanno consentito di confermare che i nucleolini, assenti nei nucleoli più piccoli, diventano sempre più numerosi coll'aumentare delle dimensioni dei nucleoli. Nelle tre specie in esame sono stati altresì ottenuti coefficienti di correlazione approssimativamente simili.     

Rapid recruitment and proliferation of antibody plague-forming cells in the absence of natural antibody

Zusammenfassung Nachweis, dass «Plaque»-bildende Antikörperzellen gegen somatische Antigene vonVibrio cholerae sich in der Milz immunisierter Mäuse schnell und «treppenartig» nach übereinstimmender Latenzzeit von 42 h entwickeln, ohne dass dabei ein «background» an Antikörper bildenden Zellen zu erfassen war.