Frozen in Time: A History of the Synthesis of Nitrous Oxide and How the Process Remained Unchanged for Over 2 Centuries.

Three major factors have contributed to the unrivaled popularity of nitrous oxide (N2O) among anesthetists in the 20th century and beyond: its impressive safety profile, its affordability, and its rapid induction and emergence times. These 3 characteristics of N2O have been discussed and written about extensively throughout the medical literature. Nonetheless, the characteristic that contributed most to N2O's initial discovery-the elegance and simplicity of its synthesis-has received substantially less attention. Although N2O was first used as an anesthetic in Hartford, CT, in 1844, it had been identified and synthesized as a distinct gas in the late 18th century. In this article, we track the developments in the recognition and early synthesis of N2O, highlight the major players credited with its discovery, and examine its evolution from the late 1700s to today. The discovery and assimilation of N2O into common medical practice, alongside ether and chloroform, heralded a new paradigm in surgical medicine-one that no longer viewed pain as a fundamental component of surgical medicine. Its continued usage in modern medicine speaks to the brilliance and skill of the chemists and scientists involved in its initial discovery.

Twinning and survivorship of captive common marmosets (Callithrix jacchus) and cotton-top tamarins (Saguinus oedipus).

Here we present the results of a demographic analysis of 25 y (1985 to 2010) of common marmoset (Callithrix jacchus) and cotton-top tamarin (Saguinus oedipus) records from the New England Primate Research Center. Summaries of longevity and survivorship are analyzed by birth-type category (including singletons, twins, triplets, and quadruplets) and sex. In addition, a brief evolutionary review is presented. Surrogates of hematopoietic chimerism, twinning, and reproductive output are explored in a large number of animals to help decipher the potential effects of chimerism on life history in marmosets and tamarins. In addition to exploring chimerism through demographic data, multiple-birth frequency and survivorship are compared between species. New World primates can make ideal translational models for disease and behavioral research across multiple disciplines. A better understanding of their reproductive success and survivorship in captivity helps develop these nonhuman primate models, their role in aging research, and understanding of their behavioral ecology. This mission is likely to only increase in its importance to biomedical research due to both the sequencing of the marmoset genome and the growing demand for alternatives to Old World primate models.