Search

The adenovirus E1a gene products are nuclear proteins important in transcriptional control of viral functions during infection. By producing normal E1a proteins and derivatives of E1a in bacteria and microinjecting these proteins into cultured cells, we were able to examine their ability to localize to the nucleus. We showed that a short peptide sequence at the carboxyl terminus of E1a is necessary for the rapid (30-min) nuclear localization of that protein. Additionally, we showed that just the last five amino acids of E1a are sufficient to direct nuclear accumulation of a heterologous protein, Escherichia coli galactokinase, with the same kinetics as native E1a. The mechanism by which this pentamer mediates rapid nuclear localization was examined by testing the ability of a galactokinase derivative which has no signal pentamer to exit the nucleus, as well as to enter it. Because neither free entry nor exit was detected, the effect of the signal is unlikely to be through increased nuclear retention of freely diffusible proteins but rather by enhancement of entry into the nucleus.

The importance of computers and simulation in management planning is reflected in this article describing a model of a hypothetical, investor-owned electric utility company. The model, which consists of three interrelated digital computer programs?an economic simulation, a cost simulation (based on power generation expenses), and an auxiliary nuclear fuel management program?is designed as a total corporate planning tool. All corporate activities, and certain environmental parameters, are represented by the economic simulation. The production cost simulation is designed to supply fuel cost information to the economic simulation and the fuel management program to supply nuclear fuel scheduling and cost data to both of the other programs. In the corporate model, management?both financial and operative?has a tool by which it is able to quickly assess the effects of one department's action upon another.

Buckwalter and Dickison 1 recently reported a new repository type of penicillin product. 2 They introduced the principle of suspending penicillin salts in peanut oil gelled with aluminum stearates, water repellent substances. They compared the absorption-delaying properties of this vehicle with the conventional repository vehicles in animals. The study recorded here was designed to carry this comparison further—in human subjects. The facilities of four assay laboratories were used, and assays were performed by two different methods, a modified Rammelkamp method and a cup plate procedure employing Sarcina lutea. Control samples of blood were drawn before the injection; each patient then received 300,000 units of penicillin in repository form, and consecutive samples of blood were taken at the intervals indicated on the chart. The lines on the chart are the lines fitted by the method of least squares to the logarithm of the average blood concentration with time in hours. Table