Studies on the regulation of the three enzymes of the Leloir pathway in cultured mammalian cells. II. A search for quantitative interrelationships between the three enzyme activities.

Studies on a normal human diploid cell strain revealed that the specific activity of the cell protein, for each of the three enzymes of the Leloir pathway, changed significantly as the cells grew. The kinetics of change in specific activity varied according to the enzyme being studied, and the kinetics for each enzyme varied from experiment to experiment. Within each experiment, there was no consistent correlation between specific activity for any one enzyme and specific activity for the other two. The ratios between the specific activities did not tend to remain constant as the absolute levels of specific activity changed. Hence, the activities did not behave coordinately. The kinetics of change in these ratios varied from experiment to experiment. The failure of galactose to stimulate increased cellular activity for the three enzymes (shown in the preceding paper), and the absence of a coordinate relationship between the activities, represent a striking difference between the behavior of these enzymes in human diploid cell strains and their behavior in E. coli.     

Inhibition of E. coli DNA polymerase I by 1,10-phenanthroline.

A 1,10-phenanthroline-cuprous ion complex is a potent reversible inhibitor of $\text{E. coli}$ DNA polymerase I yielding 50% inhibition in the micromolar concentration range. The 2:1 1,10-phenanthroline-cuprous ion complex is most probably the inhibitory species. Complexes of cupric ion and 1,10-phenanthroline have no apparent kinetic effect. The previously reported inhibition of the enzyme by 1,10-phenanthroline (1,2) is most likely due to the formation of this complex from thiols normally added to the assay mixtures and trace amounts of cupric ion invariably present notwithstanding reasonable precaution. The reversible and instantaneous 1,10-phenanthroline inhibition observed for other polymerases may be due to this unique inhibitory species and not coordination of a catalytically important zinc ion at the active site by the chelating agent.     

Infective Factors in Exacerbations of Bronchitis and Asthma

Infections of the respiratory tract were studied in a group of families each containing a patient with chronic bronchitis or with asthma. A wide variety of infective agents may be associated with exacerbations in susceptible subjects, but the types of organism to which patients are most at risk differ according to the family structure. Exacerbations in the susceptible subject are more likely to be related to viral infections when the family contains children than when it does not.Two patients with asthma experienced frequent respiratory infections, many of which provoked attacks of asthma.     

Rotator cuff muscle function and its relation to scapular morphology in apes

It is widely held that many differences among primate species in scapular morphology can be functionally related to differing demands on the shoulder associated with particular locomotor habits. This perspective is largely based on broad scale studies, while more narrow comparisons of scapular form often fail to follow predictions based on inferred differences in shoulder function. For example, the ratio of supraspinous fossa/infraspinous fossa size in apes is commonly viewed as an indicator of the importance of overhead use of the forelimb, yet paradoxically, the African apes, the most terrestrial of the great apes, have higher scapular fossa ratios than the more suspensory orangutan. The recent discovery of several nearly complete early hominin scapular specimens, and their apparent morphological affinities to scapulae of orangutans and gorillas rather than chimpanzees, has led to renewed interest in the comparative analysis of human and extant ape scapular form. To facilitate the functional interpretation of differences in ape scapulae, particularly in regard to relative scapular fossa size, we used electromyography (EMG) to document the activity patterns in all four rotator cuff muscles in orangutans and gibbons, comparing the results with previously published data for chimpanzees.