Orientation of methanolic attack on the K-region epoxide of 7,12-dimethylbenz (a) anthracene

Methanolysis of the K-region epoxide of 7,12-dimethylbenz (a) anthracene (DMBA) gave rise to two hydroxy-methoxy derivatives which were dehydrated to 5-methoxy-DMBA and 6-methoxy-DMBA at a ratio of 5:1. The data indicate that methanol attacks preferentially at the 5-position of the arene oxide. These results are in accord with steric considerations of reactivity.     

Specific thyroxine receptors in mammary cytosol from lactating cattle

Specific thyroxine (T₄) binding was identified in bovine mammary cytosol preparations. Binding specificity of 3,5,3′ triiodothyronine (T₃) with respect to T₄ was less than 1%. The halftime of T₄ binding and displacement at 4°C was 1 and 20 minutes, respectively. Scatchard analyses demonstrated the presence of two T₄ binding components with dissociation constants of 3.61 × 10^?10 and 7.73 × 10^?8M. The high affinity binding component had a molecular weight of ～ 100,000, a T₄ binding capacity of 5.05 × 10^?12moles/mg protein, and was destroyed by boiling or protease treatment. High-affinity, low capacity T₄ binding was not found in bovine serum and was unique to mammary tissue.     

What is “language” that can facilitate the flow of information? a contribution to a fundamental theory of language and communication

A theory of language is derived for complex systems by contrasting the difference between “hard” systems and “soft” systems. Complexity in a field system made up of atomistic entities is defined by the capability of the atomistic-like entities in soft systems to absorb energy internally into fluid-like, gel-like, dissipative processes rather than to equipartition energy rapidly among all degrees of atomistic freedom. Language then emerges as the “mechanistic” linkages that can catalytically switch or evoke changed atomistic states in such “soft” systems. A note on the source of syntax is also provided.     

Redox potential dependence of photophosphorylation and electron transfer in continuous illumination of Rhodopseudomonas sphaeroides chromatophores

The rate of ethanol elimination in fed and fasted rats can be predicted based on the liver content of alcohol dehydrogenase (EC 1.1.1.1), the steady-state rate equation, and the concentrations of substrates and products in liver during ethanol metabolism. The specific activity, kinetic constants, and multiplicity of enzyme forms are similar in fed and fasted rats, although the liver content of alcohol dehydrogenase falls 40% with fasting. The two major forms of the enzyme were separated and found to have very similar kinetic properties. The rat alcohol dehydrogenase is subject to substrate inhibition by ethanol at concentrations above 10 mM and follows a Theorell-Chance mechanism. The steady-state rate equation for this mechanism predicts that the in vivo activity of the enzyme is limited by NADH product inhibition at low ethanol concentrations and by both NADH inhibition and substrate inhibition at high ethanol concentrations. When the steady-state rate equation and the measured concentrations of substrates and products in freeze-clamped liver of fed and fasted rats metabolizing alcohol are employed to calculate alcohol oxidation rates, the values agree very well with the actual rates of ethanol elimination determined in vivo.     

Retention of K at low temperature in mouse L cells before and after cold adaptation

When exposed to 5 °C for periods of 3–4 weeks, mouse L cells, grown as monolayer cultures, lose K more slowly than do diploid mammalian cells. Subcultures of mouse L cells previously exposed to low temperature for intermittent periods lose K more slowly than subcultures not previously cold exposed. The superior retention of K in the cold may account in part for the better survival in the cold of mouse L cells than of diploid cells, and of cold-conditioned L cells than of unconditioned L cells.     

Interaction of tritiated beta-endorphin with rat brain membranes

The potential usefulness of disaturated lecithin titer in plasma as an indicator of the presence of atherosclerosis has led to the development of a quantitative analytical method for the $\text{16:0}\text{16:0}$, $\text{16:0}\text{18:0}$, and $\text{18:0}\text{18:0}$ lecithins in plasma. The method employs extensive sample preparation to form diglyceride acetate derivatives, which are then separated by capillary column gas-liquid chromatography. The precision of the method is ±5% or better. Suggestions for large sample population analyses are included.     

Ascorbic acid modulation of splenic cell cyclic GMP metabolism.

Chronic ascorbate deprivation of guinea pigs decreased splenic cell cyclic GMP levels (80%); ascorbate (1 mM) addition to these cells $\text{in vitro}$ restored the cellular concentration to control levels. Splenic cells from non-scorbutic animals also exhibited increases in cyclic GMP levels in response to exogenous ascorbate whereas thiol reducing agents diminished cellular cyclic GMP concentration. Agents that inhibit the propagation of free radicals prevented this cellular effect of ascorbate while agents known to interfere with or promote H₂O₂ production had no effect. Guanylate cyclase activity in cell lysates increased after treatment of intact cells with ascorbate; dithiothreitol reversed this effect. Ascorbate also enhanced guanylate cyclase activity in cell lysates. The results suggest that oxidizing equivalents in the form of the monoanionic free radical of ascorbate alter cyclic GMP metabolism in these cells by activating guanylate cyclase via a mechanism involving oxidation of a cyclase-related component.