Radioimmunoassays for androsterone, 5alpha-androstane-3alpha, 17beta-diol and 5alpha-androstane-3beta, 17beta-diol

Androsterone (3alpha-hydroxy-5alpha-androstan-17-one), 5alpha-androstane-3alpha, 17beta-diol and 5alpha-androstane-3beta, 17beta-diol were conjugated at C-16 through sulfur to bovine and human serum albumin. Rabbits injected with these conjugates produced antibodies suitable for radioimmunoassays of these hormone metabolites. Samples were purified on Sephadex LH-20 columns. Levels of these steroids were measured in a rat blood serum pool and in ovarian tissue extract pools.     

Influences of cell volume and adrenalectomy on cation flux in dog red blood cells

Rates of ²⁴Na and ⁴²K entry into dog red blood cells were found to be strongly influenced by cell volume. The kinetics of isotope movement were complex, and the cells were not in a steady state. By applying a simple, two-compartment equation to the early times points, values for flux were calculated and corrected for the changes in surface/volume ratio which occur when cells are shrunken or swollen. Curves were thus generated showing Na and K influx as functions of cell water content. A reinvestigation of the effects of adrenalectomy showed that all the observd changes in Na flux could be explained on the basis of alterations in red cell volume.     

Binding equations for interacting systems comprising multivalent acceptor and bivalent ligand: application to antigen-antibody systems

Consideration is given to the reversible interaction of a bivalent ligand, B, with a multivalent acceptor, A (possessing f reactive sites) which leads to the formation of a series of complexes, A_iB_j, comprising networks of alternating acceptor and ligand molecules. A binding equation is derived on the basis of a site association constant, k, defined in terms of reacted site probability functions. This equation, which relates the binding function, r (the moles of ligand bound per mole of acceptor) to the concentration of unbound ligand, m_b, is used to show that plots of r vs. 2km_B constructed with fixed but different values of $\text{k}\text{m}{}_{\mathrm{A}}$ intersect at the point ($\text{m}{}_{\mathrm{B}}\text{=}\text{1}\text{2k}\text{, r =}\text{f}\text{2}$) where the extent of reaction and the concentrations of those complexes for which $\text{j}\text{i}\text{=}\text{f}\text{2}$ attain maximal values. Corresponding Scatchard plots are shown by numerical example to be non-linear, their second derivative being positive for all r. It follows that such deviations from linearity cannot be taken alone as evidence for site heterogeneity in cross-linking systems. The binding equation obtained directly is shown to be identical with that obtained with f = 2 by summation procedures involving the general expression for concentrations of complexes, m_AiBj, formulated in terms of appropriate statistical factors. In this way, previous findings on precipitation and gel formation in cross-linking systems are correlated with the present development of binding theory.     

约翰·莱尔的人文生态智慧：中西融合的人文生态系统设计思想

中国传统道家生态智慧从哲学层面建立了人地关系的至高至善的标准,对从根源指导生态规划设计具有重要价值。在西方科学理性和技术理性的背景下,约翰·莱尔提出了“道家方式是人文生态系统设计的正确方式”的观点,并认为伊恩·麦克哈格设计的伍德兰兹社区正是西方人充分借鉴吸收道家智慧和道家方式的集中体现。从土地利用与空间布局、自然排水系统、调蓄机制和后期管理4部分探讨伍德兰兹社区现代生态适宜性分析技术与传统道家生态思想的契合,并探索道家思想与现代生态规划设计思想的融合的特征与规律,为生态规划设计提供一种具有创造性实践意义的新思路。     

Synthesis of ceramides and cerebrosides in rat brain: comparison with synthesis of lignoceroyl-coenzyme A

The α-hydroxylation and conversion of lignoceric acid into ceramide, cerebroside, and water-soluble products in particulate fractions from rat brain was studied in the presence of sphingosine and UDP-galactose, with particular reference to the effects of CoA and the synthesis of lignoceroyl-CoA. The synthesis of lignoceroyl-CoA was found to be almost completely dependent on the addition of exogenous CoA, whereas the formation of water-soluble products, mostly glutamate, was stimulated by, but was not stringently dependent on the addition of CoA. In contrast to these two metabolic pathways, both the synthesis of ceramides and cerebrosides and α-hydroxylation were unaffected by the addition of CoA. While removal of sphingosine and UDP-galactose had drastic effects on the sphingolipid synthesis, COA did not have any effect on the removal. On the other hand, removal of sphingosine resulted in a significant increase of the synmthesis of lignoceroyl-CoA and moderate increase in the formation of water-soluble products. These observations further indicated that CoA ester formation may not be required for the synthesis of these sphingolipids, and suggest that there may be two pathways for oxidative degradation of lignoceric acid in brain—one CoA-dependent and the other CoA-independent.     

Factors affecting the transformation of 'Marshall McIntosh' apple by Agrobacterium tumefaciens

The goal of this research was to develop an efficient transformation system for 'Marshall McIntosh' apple. To determine the optimum combination of agar and Gelrite gelling agents in the media to maximize regeneration and minimize hyperhydicity (vitrification), the following combinations of agar (A)+Gelrite (G) in g l-1 were tested: 7.0 A+0 G; 5.2 A+0.6 G; 3.5 A+2.5 G; 1.7 A+1.8 G; and 0 A+2.5 G. Both 5.2 A+0.6 G and 3.5 A+1.2 G provided greatest regeneration of healthy non-hyperhydric shoots. To determine the optimal concentration of aminoglycoside for the selection and regeneration of transgenic 'Marshall McIntosh' on agar-Gelrite-based media, kanamycin was tested at 0, 10, 25, 50, 75 and 100 mg l-1, and paromomycin was tested at 0, 50, 100, 150, 200 and 250 mg l-1. Kanamycin was more effective than paromomycin in the initial selection of transgenics. For selection of transformants of 'Marshall McIntosh', the use of kanamycin at 25 mg l^-1on 5.2 A+0.6 G solidified medium is suggested. By optimizing the medium and selection conditions, a protocol was developed that resulted in four transgenic lines as confirmed by a GUS assay, NPT II ELISA, PCR, and Southern analysis. In repeated experiments with this protocol, transformation efficiencies of 3.1 and 2.6% were obtained. This revised version was published online in June 2006 with corrections to the Cover Date.     

Binding of terbium(III) to yeast enolase

Several independent criteria indicate 2 mol of terbium(III) bind to yeast enolase in the absence of substrate-fluorescence titrations of enzyme and metal, effects on thermal stability and published ultrafiltration and inhibition experiments. These measurements also suggest the terbium binding sites are the same as those normally occupied by “conformational” magnesium. Terbium binds much more strongly than magnesium, however, and measurements of the kinetics of the absorbance change in the terbium-enzyme on adding excess EDTA suggest the terbium-enzyme dissociation constant is about $\text{1}\text{500}$ that of the magnesium-enzyme. Measurements of enzyme activity as a function of substrate concentration show that terbium permits no enzymatic activity. However, magnesium competes more effectively with the lanthanide if the substrate analogue 3-aminoenolpyruvate 2-phosphate (AEP) is present.The fluorescence of the lanthanide is not readily observed on exciting the terbium-enzyme at 280 nm, indicating the absence of tyrosines or tryptophans in the coordination sphere of the metal. Excitation of terbium using 488 nm radiation from an argon ion laser shows the fluorescence of the metal is enhanced by binding to the enzyme. EDTA and carbonate have similar effects. This suggests carboxyl groups are involved in binding metal at the conformational sites of yeast enolase. Measurements of lifetimes of enzyme-bound terbium in the presence and absence of D₂O indicated three moles of water remained on each of the bound metals, independently of the buffer used. If enzyme-bound terbium is assumed to be nine-coordinate, the metal must bind to six groups from the enzyme. The presence of substrate does not markedly affect the emission spectrum of the bound terbium or the number of water molecules remaining on the metal, but calorimetric measurements show that substrate binds to the terbium enzyme.     

JUSTICE, STIGMA, AND THE NEW EPIDEMIOLOGY OF HEALTH DISPARITIES

Recent research in epidemiology has identified a number of factors beyond access to medical care that contribute to health disparities. Among the so-called socioeconomic determinants of health are income, education, and the distribution of social capital. One factor that has been overlooked in this discussion is the effect that stigmatization can have on health. In this paper, I identify two ways that social stigma can create health disparities: directly by impacting health-care seeking behaviour and indirectly through the internalization of negative interpersonal judgments. I then argue that social arrangements that foster self-respect can reduce the impact of stigmatization on health disparities. I conclude by showing how John Rawls' conception of justice can be used to address the intersection of stigma, health, and self-respect, in contrast to critics of his position, who have seen him as excessively focused on the allocation of material goods.