In addition to the usual amino acids and vitamins, Lactobacilus delbrekii strain 730 (ATCC 9649) has been shown to require pyridoxamine phosphate (McNutt and Snell, 1950), thymidine (Kitay, et al., 1950), and an unsaturated fatty acid (e. g., oleic acid) (Kitay and Snell, 1950) for growth. In addition to these absolute requirements for growth, partial acid hydrolyzates of casein further stimula...

Microbiological tests have aided greatly in the isolation work on “L&o!x~ciZZus casei factor,” demonstrated by Snell and Peterson in 1940 (l), and “folic acid,” the nutrient required by Streptococcus lactis R as defined by Mitchell et al. (2). It seems likely that bacterial assays will continue to play an important role in the study of these compounds, since development of chemical methods has ...

Previous studies have shown that dermal fibroblast cell lines derived from young adult mice of the long-lived Snell dwarf mutant stock are resistant, in vitro, to the cytotoxic effects of H(2)O(2), cadmium, UV light, paraquat, and heat. We show here that similar resistance profiles are seen in fibroblast cells derived from a related mutant, the Ames dwarf mouse, and that cells from growth hormo...

A new grid method for computing the Snell envelop of a function of a R d -valued Markov chain (Xk)0≤k≤n is proposed. (This problem is typically non linear and cannot be solved by the standard Monte Carlo method.) Every Xk is replaced by a “quantized approximation” X̂k taking its values in a grid Γk of size Nk. The n grids and their transition probability matrices make up a discrete tree on which...

The involvement of mammalian target of rapamycin (mTOR) in lifespan control in invertebrates, calorie-restricted rodents, and extension of mouse lifespan by rapamycin have prompted speculation that diminished mTOR function may contribute to mammalian longevity in several settings. We show here that mTOR complex-1 (mTORC1) activity is indeed lower in liver, muscle, heart, and kidney tissue of Sn...

Previous reports from this laboratory have shown that pantothenic acid is essential for the growth of every species of lactic acid bacteria tested (Snell et al., 1937). It has also been shown that while some species of lactic acid bacteria require riboflavin for growth, several do not (Snell and Strong, 1939). In a study of the activity of certain synthetic flavins, a close correlation was foun...

The literature on the immunological aspects of tumor transplantation has been well reviewed by Hauschka (9), so it is necessary only to point out certain technical problems that form the basis for the present communication. The most striking recent advances in our knowledge of the genetics of tumor transplanta tion have been due to the work of Snell and his colleagues on the H-2 locus (13) and ...

In this paper we study the pricing problem of multiple exercise options in continuous time on a finite time horizon. For the corresponding multiple stopping problem, we prove, under quite general assumptions, the existence of the Snell envelope, a reduction principle as nested single stopping problems, and a Doob-Meyer type decomposition for the Snell envelope. The main technical difficulty ari...