Emmanuel A. Nunez

Interactions between phytoestrogens and human sex steroid binding protein

The interactions of human Sex steroid binding protein (SBP) and the lignans [Nordihydrogaiaretic acid (NDGA) enterolactone (Ent), enterodiol (End)] and isoflavonoid phytoestrogens [Equol (Eq), diazein Dad), genistein (Gen)] were studied. The phytoestrogens had different dose-dependent inhibitory effects on steroid binding by SBP. Their relative efficiencies were: Ent> or = NDGA = Eq > Gen for displacing E2 and Eq > Ent > NDGA > Gen for displacing T. End and Dad were much less active. Scatchard analysis suggested that NDGA had similar non- competitive effects on T and E2 binding by reducing the number of binding sites without changing the association constants. But Eq seemed to inhibit E2 binding non-competitively and T binding competitively. NDGA binding to SBP reduced the immunorecognition of SBP by monospecific anti-SBP antibodies, suggesting that NDGA changed SBP immunoreactivity. Unlike NDGA, Eq binding to SBP caused no immunological changes in SBP, indicating qualitative differences in the effects of the lignan and isoflavonoid. Our results indicate that phytoestrogens may modulate the SBP activity and so influence the role of this protein in the delivery of hormonal information to sex steroid-dependent cells.

Role of fatty acids in signal transduction: Modulators and messengers

Many of the steps involved in signal transduction are regulated positively or negatively by fatty acids (FA) per se. FA have been shown to act both as modulators and messengers, particularly of signals triggered at the level of cell membranes. Enzymes and proteins of the cyclic AMP and the protein kinase C signalling pathways and those involving ion fluxes and mobilization are both activated and/or inhibited by FA. FA can also participate in a feedback control mechanism since phospholipases are themselves modulated by FA. FA, particularly arachidonic acid liberated from membrane phospholipids, are also second messengers in signal transduction, and a good example is the activation of protein kinase C by FA. FA play an important role in regulating the transmission of signals from the extracellular environment by acting as modulators and messengers within the complex intracellular network of relays.

Elevated oestrogen and reduced testosterone levels in the serum of male septic shock patients

The variations in oestrogen levels which occur in men with septic shock were determined and analysed in terms of the changes seen in the levels of other steroid hormones of testicular and adrenal origin. The concentrations of the hormones, oestrone (E1), oestradiol (E2), testosterone (T), delta 4-androstenedione (delta 4), cortisol (F) and progesterone (P4) were determined by radioimmunoassay. The serum levels of cholesterol, triglycerides, phospholipids and non-esterified fatty acids (NEFAs) were also determined. Two groups of male septic shock patients were studied within the first 24 h following the admission to the Intensive Care Unit. Group I (n = 24) patients died. Group II (n = 22) patients recovered. Both groups were compared to a control group (n = 44) of healthy men. In group I patients, serum E1 levels were 3900 +/- 900 pmol/l, 12-fold higher than controls (296 +/- 22 pmol/l) [P less than 0.001], serum E2 levels were 880 +/- 170 pmol/l, 6-fold above control levels (158 +/- 30 pmol/l) [P less than 0.001] and serum T levels were 1.7 +/- 0.3 nmol/l, 11-fold lower than in controls (18.7 +/- 1.9 nmol/l) [P less than 0.001]. Serum P4 and F levels were slightly increased (P less than 0.05) and delta 4 androstenedione levels were unchanged. Groups II serum estrogen levels (814 +/- 350 pmol/l) [P less than 0.01] were higher than controls and serum T levels were 2-3 times less than control levels (5.5 +/- 2 nmol/l) [P less than 0.01]. The group II serum P4, F and delta 4 androstenedione levels did not differ from control levels. The levels of cholesterol, triglycerides, phospholipids and NEFAs were all decreased to similar, significant, degrees in both groups of shock patients. The dramatic increase in E1 levels associated with the decrease in T suggests an adrenal-testicular relationship with possible potentiation of aromatization of adrenal or testicular androgens in men in septic shock. The determination of serum E1 and T during septic shock in men could form the basis for prognostic estimations of septic shock severity and for a new therapeutic approach to shock.

Serum depletion of corticosteroid binding activities, an early marker of human septic shock

Abstract We report that human sera within 24 hours after the onset of septic shock are virtually depleted of the corticosteroid binding activities characteristic for transcortin. By contrast, transcortin activities are not changed significantly in cases of acute inflammation, though septic shock and inflammatory sera are comparable in other respects: they show similar responses of their haptoglobin, thyroxine binding prealbumin, endogenous cortisol and progesterone levels. The physiological meaning and clinical interest of these results are discussed.

Phytoestrogens : new ligands for rat and human α-fetoprotein

Abstract The binding of the lignans, enterolactone, enterodiol, nordihydroguaiaretic acid (NDGA), and the isoflavonic phytoestrogen equol, to human and rat α-fetoprotein (AFP) was studied. They had differential inhibitory effects (NDGA > equol > enterolactone > enterodiol) on the binding of estrone and estradiol to rat AFP and the binding of unsaturated fatty acid to both rat and human AFP. Inhibition was dose-dependent. The apparent dissociation constants (Kd) for phytoestrogens binding to AFP were: Kd NDGA = 5 ± 1.2 · 10−7 M, Kd equol = 6.7 ± 0.8 · 10−6 M, Kd enterolactone = 1.7 ± 0.4 · 10−5 M and Kd enterodiol = 2.2 ± 0.6 · 10−5 M. The Kd for estrone binding to rat AFP was increased by increasing concentrations of equol, but the number of estrone binding sites remained unchanged. This, plus the results of double-reciprocal plots, suggests that they compete for the same site(s). NDGA also competitively inhibited estrone binding at low NDGA concentrations (increased Kd), but high concentrations induced conformational changes in rat AFP, as both Kd and the number of binding sites (n) were altered. Both rat and human AFPs underwent changes in electrophoretic behaviour and loss of immunoreactivity with increasing NDGA, suggesting that NDGA binding induces conformational changes in the AFPs. However, equol did not alter the electrophoretic or immunological properties of either rat or human AFP, providing further evidence for qualitative differences in the effects of these diphenols. These findings indicate that phytoestrogens could play a role in AFP-dependent normal and pathological growth and development.

Abnormal free fatty acids and cortisol concentrations in the serum of AIDS patients

The serum free fatty acid (FFA), cortisol and urinary creatinine, 17-hydzoxycorticosteroid and 17-oxosteroid concentrations of acquired immunedeficiency syndrome (AIDS-I: beginning and AIDS-II: end phase) and AIDS-related complex (ARC) patients were determined. Both groups were compared to a control group (healthy men). ARC and AIDS-I patients. The ratios of stearic (C18:0) to oleic (C18:1) acid were 75%, P less than 0.01 (ARC) and 45%, P less than 0.05 (AIDS-I) greater than normal, due to a decrease in the relative percentage of monounsaturated fatty acids by 25%, P less than 0.001 (ARC) and 20%, P less than 0.01 (AIDS-I). In contrast, the relative percentage of polyunsaturated fatty acids was 85% greater than normal (P less than 0.001) in ARC and 100% greater than normal (P less than 0.001) in AIDS-I patients. Total FFA levels did not differ from controls. Serum cortisol levels were 35% (P less than 0.01) above normal in ARC and 60% (P less than 0.001) above normal in AIDS-I patients. Urinary 17-hydroxycorticosteroids and 17-oxosteroids were very low (2-3-fold lower than normal values, P less than 0.001) in both groups of patients. Urinary creatinine did not differ from controls. In AIDS-II patients the total FFA concentration was below normal 35% (P less than 0.01) and the stearic/oleic acid ratio was 50% above normal (P less than 0.05). The relative percentages of monounsaturated and polyunsaturated fatty acids in this group were similar to those of controls. Serum cortisol concentrations were significantly higher, 50% (P less than 0.001), but the urinary 17-hydroxycorticosteroids and 17-oxosteroids were 2-fold lower (P less than 0.001) than those of controls. Urinary creatinine did not differ from controls. These significant differences from normal may be implicated in the pathophysiology of AIDS and could represent not only a good index of diagnosis and prognosis, but also indicate new therapeutic approach to the disease.

Affinity chromatography purification of rat αn1-foetoprotein

During the last ten years, the foetal and carcinoma antigens, particularly the al -foetoprotein (AFP) have been much studied [l] . The hypothesis of the involvement of the 01~ foetoprotein in cellular differentiation, during foetal or tumor development, has been the starting point of many researches in immunology and oncology [2,31* One of the necessary steps in these studies is the preparation of ponderal amounts of native AFP. Several purification methods have already been described [4-61. We present here a simplified method of preparation of rat AFP by affinity chromatography.

A thyroxine binding globulin (TBG)-like protein in the sera of developing and adult rats

We report evidence based on equilibrium binding, electrophoretic, autoradiographic studies, that the rat possesses a major high affinity thyroid hormone binding protein, with an electrophoretic mobility and binding properties similar to those of the human thyroxine binding globulin (TBG). We show that in the sera of postnatal developing animals, the thyroxine and the triiodothyronine binding activities increase up to 10 times over adult or foetal levels, due to a high transient post-natal surge of the rat TBG. In the adult serum, the TBG persists in decreased amounts: it then yields the predominant role as thyroxine carrier to the thyroid binding prealbumin, but retains the major role as binder of triiodothyronine i.e. of the biologically active thyroid hormone.

The hepatic biosynthesis of rat thyroxine binding globulin (TBG): Demonstration, ontogenesis, and UP-regulation in experimental hypothyroidism

Using a human thyroxine binding globulin (TBG) cDNA probe, we demonstrate that rat liver contains two TBG mRNA species of different length, consisting of about 1.8 Kb and 2.4 Kb respectively. Slot blot analysis of the hepatic mRNAs from rats of different age reveals a fair correlation between the developmental trend of the messengers and that of the TBG circulating levels. Finally Northern blot and slot studies demonstrate that the increase of serum TBG induced in adults by thyroidectomy actually reflects an enhanced hepatic biosynthesis of the protein.

In vivo effect of free fatty acids on the specific binding of glucocorticosteroids to corticosteroid binding globulin and liver receptors in immature rats

Stimulating lipase activity with heparin (200 IU/kg b.w.) increased the plasma free fatty acid (FFA) concentration of immature rats (15 days). The effect of this elevated FFA concentration on glucocorticoid binding to corticosteroid binding globulin (CBG), and liver cytosol glucocorticoid receptor (GR), was analyzed. The plasma FFA concentration increased 2-fold, 10 minutes (P < 0.001), 20 minutes (P < 0.01), and 60 minutes (P < 0.01) post-heparin. The corticosterone (B) and progesterone concentrations were unchanged 60 minutes post-injection. The binding activity of immature rat CBG for B dropped 50% (P < 0.001) 60 minutes post-heparin injection, decreased B binding and increased plasma FFA were correlated (r = -0.8). The decreased B binding resulted from a 2-fold decrease in the apparent number of CBG binding sites; the affinity constant (Ka) remained unchanged. The liver cytosol endogenous FFA content of immature rats was also increased 2-fold, 60 minutes after heparin-induced lipolysis. The increased cytosol FFA, with no significant change in glucocorticoid, was accompanied by a significant decrease in dexamethasone binding to liver cytosol glucocorticoid receptor. The decrease resulted from a significantly lower apparent Ka for dexamethasone and fewer receptor binding sites (n). There was a good inverse correlation between Ka (r = -0.93) and n (r = -0.90) and the increased liver cytosol FFA content. Thus the higher plasma FFA induced in vivo by lipase activation or a standard FFA mixture probably causes conformational changes in CBG and GR, reducing glucocorticoid binding to immature rat CBG and liver GR.