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B Benedict

Publications and source records attributed to B Benedict.

6 recordsLinked to original sources

Neurological deterioration as a potential alternative endpoint in human clinical trials of experimental pharmacological agents for treatment of severe traumatic brain injuries. Executive Committee of the International Selfotel Trial.

OBJECTIVE: A recently improved understanding of the pathophysiological features of head injuries has led to the development of new drug therapies. Accurate human clinical trials remain necessary to document the efficacy and safety of new agents. It would be helpful to decrease the time from drug development to clinical use and general availability for drugs found to be effective. Conversely, ineffective agents could be abandoned in a timely fashion. RATIONALE: A new endpoint measure, defined as neuroworsening (NW), is an objective observable event that is identifiable during hospitalization. This may enable the efficacy of drugs to be demonstrated or disproved much earlier than with 6-month outcome assessments. The prospective, double-blind, multicenter trial of the N-methyl-D-aspartate receptor antagonist Selfotel was used to acquire data on the efficacy of NW in predicting neurological outcomes. The 6-month Glasgow Outcome Scale scores, which were the primary endpoints of that trial, were compared with the frequency of NW. NW was an observable event that could be objectively defined after head injuries. Patients who suffered one or more episodes of NW demonstrated significantly higher morbidity and mortality rates than did patients who did not. CONCLUSION: Future trials should consider the use of NW as an outcome measure that can be included with more traditional measures in the study design. If the strong correlation demonstrated between NW and 6-month Glasgow Outcome Scale scores can be prospectively demonstrated in a successful trial, the time to approval of future agents could be decreased.

Adult↗

Mechanochemical coupling in flagella. IV. Absence of coupling between metabolism and motility in Chaetopterus spermatozoa.

The metabolic rate of suspensions of spermatozoa from the annelid worm, Chaetopterus, does not change significantly when the viscosity of the suspension is increased by the addition of methyl cellulose. At high viscosities, where the spermatozoa swim with about 1/3 the normal beat frequency and 1.5-1.8 times the normal bend angle, the calculated power output against external viscous resistances increases to 4-5 times its normal value. This large increase in power output can be accommodated without an increase in metabolic rate only if internal viscous resistances to flagellar bending are relatively low.

Animals↗

Mechanochemical coupling in flagella. II. Effects of viscosity and thiourea on metabolism and motility of Ciona spermatozoa.

The relation between oxygen consumption and motility of Ciona spermatozoa has been measured by using pH stats to measure the acid production of spermatozoa swimming in dilute suspensions where their motility can be analyzed accurately, and calibrating the acid production by measuring it simultaneously with measurements of oxygen consumption, using more concentrated sperm suspensions. When the motility of the spermatozoa is inhibited by thiourea or by increased viscosity, their oxygen consumption decreases in proportion to the decrease in beat frequency. 80-85 % of their oxygen consumption appears to be tightly coupled to motility. The amount of movement-coupled oxidative metabolism per beat remains nearly constant, even when there are significant changes in the energy required per beat for movement against the viscous resistance of the medium. This implies that under these conditions, where the radius of curvature of flagellar bending remains constant, the amount of ATP used is determined by a stoichiometric relation to bending rather than by the energy requirement. The movement-coupled oxidative metabolism appears to be sufficient to generate approximately two molecules of ATP per beat for each molecule of the flagellar ATPase, dynein.

Acids↗