From microscopic to macroscopic description of multicellular systems and biological growing tissues

✦ Synopsis

This paper presents an asymptotic theory for a large class of Boltzmann-type equations suitable to model the evolution of multicellular systems in biology. The mathematical approach described herein shows how various types of diffusion phenomena, linear and nonlinear, can be obtained in suitable asymptotic limits. Time scaling related to cell movement and biological activity are shown to play a crucial role in determining the macroscopic equations corresponding to each case.

Acute and Chronic Toxicity of Veratrum V

Acute and Chronic Toxicity of Veratrum Viride††The Veratrum viride studied was the whole-powdered drug marketed by Irwin, Neisler & Co. under the name, Vertavis. The work reported herein was supported by a grant from this firm. The batch of powder used in these experiments was stated by the manufacturer to have been assayed biologically by the Craw method on Daphnia magna. One Craw unit of the material studied was stated to be 15.6mg. With regard to this assay, Mr. R. O. Craw has been so kind as to allow us to publish a brief explanation: A reference lot of Yerolrum oirid; powder was set-aside as a standard and a 10% w/v aqueous extract was made of this powder. The average median length of life in 50 assays of 1000 daphnia on immersion in the solution was determined to be 2.22 hours. The daphnia were considered dead when the heart was found to be in systolic standstill on microscopic examination. Succeeding lots of powder were assayed and their potency determined by relating the median length of life of daphnia to 2.22 hours, which is one unit. Twenty assays of 10 animals each were used on each lot of powder.‡‡The authors wish to thank Dr. J. F. A.,McManus of the Department of Pathology for a pathologic report on the tissues, and Mr. James Thomas and Mrs. Bobby E. Teague for technical assistance.

✍ Perdue, Adoline S. ;Bell, Frances ;Starnes, W.R. ;Hitchcock, Philip ;Teague, R.S 📂 Article 📅 1950 🏛 Elsevier ⚖ 346 KB 👁 1 views