PubMed · 9783735
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1998. Journal evolution.. https://doi.org/10.1038/2277
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We highlight conditions under which coincidence of van't Hoff and calorimetric enthalpies can be experimentally verified for reactions of biochemical interest. First, we clarify that, often, chemical equations in condensed phase do not explicitly contain information on all processes involved. Second, we underline that the accuracy of electrochemical methods is much higher than that of other non-calorimetric techniques. Electrochemical data on the binding of ethidium ion to DNA are re-examined to verify that the entropy evaluated as the temperature derivative of the free energy agrees in full with the calorimetric one. Third, we point out that unfolding or self-association enthalpies of redox proteins can be reliably obtained by electromotive force measurements, taking advantage of their linkage to redox enthalpies. Thermodynamic cycles coupling biochemical transformations to redox systems are briefly discussed.
In this work we attempt to analyze the coupling between the dynamics of biochemical reactions (especially chaotic dynamics), and the geometry of cytoarchitecture (especially fractal ultrastructure), because of its importance and consequences for the ultradian dynamic behaviour of cells. Fractal geometry in intracellular macromolecular assemblies suggests that chaotic dynamics occur during their organization. Non-linear interactions in and between spatial and temporal domains and over wide ranges of scales underlie the emergent properties of complex biological systems.
AIM: To investigate the correlation between immunohistochemical and biochemical steroid receptor analyses by measurement of oestrogen, progesterone, and androgen receptor status in ovarian neoplasia. METHODS: Tissue samples were obtained from 27 ovarian neoplasms, including two borderline tumours. Immunohistochemical staining of the tissue slides was scored semiquantitatively, incorporating the intensity and percentage of positive staining (histo-score). Tumours with a histo-score of 10 or more were considered steroid receptor positive. The epithelial and stromal fractions of the tumours were analysed separately. To study the uniformity of receptor expression throughout a tumour, up to four samples were analysed. RESULTS: Immunohistochemical histo-scores of the oestrogen receptor in the epithelial fractions were significantly correlated with the biochemical oestrogen receptor values (r = 0.408). Androgen receptor status in the epithelial fraction was correlated with that in the stromal fraction (r = 0.741), while androgen receptor histo-scores in the epithelial fraction correlated with the biochemical assay values (r = 0.463). On biochemical analysis, 17 of the 27 ovarian tumours were oestrogen receptor positive and seven were progesterone receptor positive. On immunohistochemical analysis, eight tumours were oestrogen receptor positive and two were progesterone receptor positive. Biochemical analysis showed that 14 of the 26 tumours were slightly androgen receptor positive (10-50 fmol/mg protein), while all the others were negative. On immunohistochemical analysis, seven of the 26 tumours were androgen receptor positive. When two or more specimens from one tumour were analysed, marked differences in steroid status were found, especially in progesterone receptor and androgen receptor expression. Some parts of a tumour were steroid receptor positive, while other parts were negative owing to heterogeneity of expression. CONCLUSIONS: Immunohistochemical and biochemical analysis of steroid receptors in ovarian tumours correlated weakly or not at all. Heterogeneity of expression within a tumour and the presence of progesterone and androgen receptors in the stromal fraction partly accounted for this observation. Biochemical and immunohistochemical androgen receptor status was much lower than in previous reports.