The fully deuterated proteins C-phycocyanin, C-phycoerythrin, and cytochrome c have been obtained by biosynthesis with the leucine side chains, and only the leucine side chains, of normal ((1)H) isotopic composition. In these (isotopic hybrid) proteins, proton magnetic resonance analysis shows that the (1)H-leucine side chains are in a variety of environments. During protein biosynthesis, the alpha hydrogen of leucine is exchanged with a hydrogen ((2)H) from the aqueous medium.
J. S. Mill, and others have expressed varying views on how a legislator ought to represent his constituency.Theorists have also offered different ideas about how legislators actually behave. Some, including Downsian theorists working with an "economic theory of democracy," expect representatives to act exactly in accord with the policy preferences of their constituents (first section of Downs, 1957). Others argue that legislators are largely free of popular control and are influenced instead by interest groups' wishes, party loyalties, peer pressures, or their own judgments.The pioneering Miller and Stokes study of 1958 made possible for the first time a systematic empirical examination of linkages between sampled public opinion and roll call voting in Congress (Miller and Stokes, Abstract Using congressional districts as primary sampling units, the 1978 National Election Survey provides improved (though still imperfect) measures of district opinion. Together with Census data on district demography, roll call voting scales, and information on congressmen's party and personal characteristics, they permit a new examination of representation in Congress. Using these data we found a high degree of representation of district opinion on social welfare and (surprisingly) on women's issues, nearly as much on racial issues, and much less on law and order or on abortion. District demography and congressmen's party add substantially to the explanation of roll call votes. There is not, however, much "responsible party" representation in Congress. Future representation studies must face questions about the complex interplay among these factors, including reciprocal influences.Benjamin 1.
Scaly skin occurs in 80-90% of patients who are hypothyroid, the pathogenesis of which is unknown. Since thyroid hormone (T3) affects growth and differentiation in other organs, we examined the effects of its absence on keratinocytes in vitro. Human neonatal foreskin keratinocytes were cultivated and second passage cells were switched to T3-depleted (-T3) medium at 50% confluence. Cells maintained in the -T3 medium demonstrated increased (1.5 fold) levels of the cross-linking enzyme transglutaminase and increased (1.5 fold) formation of cornified envelopes, when compared to keratinocytes maintained in medium containing physiologic levels (2 X 10(-9)M) of T3. Additionally, in the -T3 cultures, the level of the protease plasminogen activator (PA), an enzyme implicated in the process of shedding of cornified cells, was decreased 70-80% of that measured in +T3 media. Absence of T3 from keratinocyte culture-medium increased both the level of the enzyme responsible for cross-linking cornified envelope precursors and the rate of envelope formation in cultured cells. The decreased levels of PA observed in the -T3 cultures could result in decreased shedding of cornified cells. These alterations in the process of keratinocyte differentiation may explain the clinically observed scaliness associated with hypothyroidism in humans. The molecular mechanism by which T3 alters keratinocyte cornification is not yet known.
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