Biological losses and the quarantine policy for mars

An international committee known as COSPAR has agreed that the probability of a single viable organism aboard any unmanned spacecraft intended for planetary landing should be kept less than 10^–3, in agreement with work by Sagan and Coleman. At present, the U.S.A. is committed to remain consistent with this standard. Using a model which includes both expected losses from failures to collect data and from contamination to analyze the quarantine problem, evidence is given which suggests that the current quarantine requirements may be too strict if their implementation forces a program delay. U.S. policy should be re-examined, keeping more fully in mind both the types and the relative sized of the losses which might be encountered.     

Inhibition by cycloserine of mitochondrial and cytosolic aspartate aminotransferase in isolated rat hepatocytes.

Isolated hepatocytes were incubated with L-cycloserine and then treated with digitonin so that mitochondrial and cytosolic fractions were obtained in 5 s. Mitochondrial and total cellular aspartate aminotransferases (EC 2.6.1.1) were inactivated in parallel. The enzyme was also inhibited in isolated mitochondria incubated with L-cycloserine. These results, in contrast with previous reports, indicate that cycloserine reacts equally with mitochondrial and cytosolic aspartate aminotransferases.     

Isolation of insulin-like growth Factors I and II from human plasma

Insulin-like growth factors I and II have been isolated from Cohn fraction IV-1 of human plasma using gel permeation chromatography, ion exchange chromatography, reversed phase chromatography, isoelectric focusing (IEF) and high performance liquid chromatography(HPLC). IGF I of specific activity 89 U/g, as measured by the isolated rat adipocyte assay, and IGF II, of specific activity 78 U/g, were obtained in yields of 16 micrograms and 34 micrograms respectively per 100g of Cohn fraction. Although this process yields IGF I which is contaminated with IGF II (due to the relatively large amount of the latter present in the original plasma), the IGF II preparations appear to be relatively free from IGF I. This separation was mainly achieved with IEF since the two factors elute close together on HPLC. Nevertheless, HPLC is important for their subsequent purification. The process is thus especially suitable for the preparation of IGF II and appears to give better yields than those obtained by earlier methods which used acid-ethanol extraction, gel permeation chromatography and polyacrylamide gel electrophoresis.