Structural variation between neuropeptide isoforms affects function in the lobster cardiac system.

Neuronal responses to peptide signaling are determined by the specific binding of a peptide to its receptor(s). For example, isoforms of the same peptide family can drive distinct responses in the same circuit by having different affinities for the same receptor, by having each isoform bind to a different receptor, or by a combination of these scenarios. Small changes in peptide composition can alter the binding kinetics and overall physiological response to a given peptide. In the American lobster (Homarus americanus), native isoforms of C-type allatostatins (AST-Cs) usually decrease heartbeat frequency and alter contraction force. However, one of the three AST-C isoforms, AST-C II, drives a cardiac response distinct from the response elicited by the other two. To investigate the aspects of the peptide that might be responsible for these differential responses, we altered various features of each peptide sequence. Although the presence of an amide group at the end of a peptide sequence (amidation) is often essential for determining physiological function, we demonstrate that C-terminal amidation does not dictate the AST-C response in the lobster cardiac system. However, single amino acid substitution within the consensus sequence did account for many of the differences in specific response characteristics (e.g. contraction frequency or force).

Louise Eisenhardt (1891-1967): World Renowned Neuropathologist, Brain Tumor Registry Director, First Editor-In-Chief of Journal of Neurosurgery, and President of Harvey Cushing Society.

BACKGROUND: This historical account reviews the course and lasting impact of Dr. Louise Eisenhardt (1891-1967) in neurosurgery. METHOD: The writing of this project was sparked by the discovery of original scientific and bibliographical information about Eisenhardt, testimony on personal relationships, and viewpoints after comprehensive compilation of information. It is a thorough review of literature on Eisenhardt and reflects the scope and depth of these prior works. RESULTS: It begins with the decisive influence of Harvey Cushing's mentorship and academic; follows Eisenhardt's impact on the development of modern neuropathology; discusses the Eisenhardt-Percival-Bailey-Cushing collaboration on gross brain specimens and histological classification of brain tumors; recounts Cushing's creation of a neuropathologist team for the Brain Tumor Registry working asynchronously with the Pathology Department at Peter Bent Brigham Hospital; Eisenhardt's aid in the development of intraoperative analysis of brain tumors; her career as a neuropathologist; her contributions as Editor-in-Chief of the Journal of Neurosurgery; and her preservation of the Brain Tumor Registry at Yale University School of Medicine estimated the largest and most valuable databank of information in the history of medicine. Eisenhardt served as President, Historian, and Secretary-Treasurer of the Harvey Cushing Society, the professional organization now known as the American Association of Neurological Surgeons, and was senior lecturer for members of the Congress of Neurological Surgeons, constituents of NEUROSURGERY Publications. CONCLUSIONS: Our article provides glimpses into the personality of Dr. Louise Eisenhardt and her marked impact on neurosurgery and allied neurosciences.