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See detailMicroRNA-146a is a therapeutic target and biomarker for peripartum cardiomyopathy.
Halkein, Julie ULg; Tabruyn, Sebastien P.; Ricke-Hoch, Melanie et al

in Journal of Clinical Investigation (2013), 123(5), 2143-54

Peripartum cardiomyopathy (PPCM) is a life-threatening pregnancy-associated cardiomyopathy in previously healthy women. Although PPCM is driven in part by the 16-kDa N-terminal prolactin fragment (16K PRL ... [more ▼]

Peripartum cardiomyopathy (PPCM) is a life-threatening pregnancy-associated cardiomyopathy in previously healthy women. Although PPCM is driven in part by the 16-kDa N-terminal prolactin fragment (16K PRL), the underlying molecular mechanisms are poorly understood. We found that 16K PRL induced microRNA-146a (miR-146a) expression in ECs, which attenuated angiogenesis through downregulation of NRAS. 16K PRL stimulated the release of miR-146a-loaded exosomes from ECs. The exosomes were absorbed by cardiomyocytes, increasing miR-146a levels, which resulted in a subsequent decrease in metabolic activity and decreased expression of Erbb4, Notch1, and Irak1. Mice with cardiomyocyte-restricted Stat3 knockout (CKO mice) exhibited a PPCM-like phenotype and displayed increased cardiac miR-146a expression with coincident downregulation of Erbb4, Nras, Notch1, and Irak1. Blocking miR-146a with locked nucleic acids or antago-miRs attenuated PPCM in CKO mice without interrupting full-length prolactin signaling, as indicated by normal nursing activities. Finally, miR-146a was elevated in the plasma and hearts of PPCM patients, but not in patients with dilated cardiomyopathy. These results demonstrate that miR-146a is a downstream-mediator of 16K PRL that could potentially serve as a biomarker and therapeutic target for PPCM. [less ▲]

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See detailNicotinic acid- and monomethyl fumarate-induced flushing involves GPR109A expressed by keratinocytes and COX-2-dependent prostanoid formation in mice.
Hanson, Julien ULg; Gille, Andreas; Zwykiel, Sabrina et al

in Journal of Clinical Investigation (2010), 120(8), 2910-9

The antidyslipidemic drug nicotinic acid and the antipsoriatic drug monomethyl fumarate induce cutaneous flushing through activation of G protein-coupled receptor 109A (GPR109A). Flushing is a troublesome ... [more ▼]

The antidyslipidemic drug nicotinic acid and the antipsoriatic drug monomethyl fumarate induce cutaneous flushing through activation of G protein-coupled receptor 109A (GPR109A). Flushing is a troublesome side effect of nicotinic acid, but may be a direct reflection of the wanted effects of monomethyl fumarate. Here we analyzed the mechanisms underlying GPR109A-mediated flushing and show that both Langerhans cells and keratinocytes express GPR109A in mice. Using cell ablation approaches and transgenic cell type-specific GPR109A expression in Gpr109a-/- mice, we have provided evidence that the early phase of flushing depends on GPR109A expressed on Langerhans cells, whereas the late phase is mediated by GPR109A expressed on keratinocytes. Interestingly, the first phase of flushing was blocked by a selective cyclooxygenase-1 (COX-1) inhibitor, and the late phase was sensitive to a selective COX-2 inhibitor. Both monomethyl fumarate and nicotinic acid induced PGE2 formation in isolated keratinocytes through activation of GPR109A and COX-2. Thus, the early and late phases of the GPR109A-mediated cutaneous flushing reaction involve different epidermal cell types and prostanoid-forming enzymes. These data will help to guide new efficient approaches to mitigate nicotinic acid-induced flushing and may help to exploit the potential antipsoriatic effects of GPR109A agonists in the skin. [less ▲]

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See detailLung interstitial macrophages alter dendritic cell functions to prevent airway allergy in mice
Bedoret, Denis ULg; Wallemacq, Hugues ULg; Marichal, Thomas ULg et al

in Journal of Clinical Investigation (2009), 119(12), 3723-38

The respiratory tract is continuously exposed to both innocuous airborne antigens and immunostimulatory molecules of microbial origin, such as LPS. At low concentrations, airborne LPS can induce a lung DC ... [more ▼]

The respiratory tract is continuously exposed to both innocuous airborne antigens and immunostimulatory molecules of microbial origin, such as LPS. At low concentrations, airborne LPS can induce a lung DC-driven Th2 cell response to harmless inhaled antigens, thereby promoting allergic asthma. However, only a small fraction of people exposed to environmental LPS develop allergic asthma. What prevents most people from mounting a lung DC-driven Th2 response upon exposure to LPS is not understood. Here we have shown that lung interstitial macrophages (IMs), a cell population with no previously described in vivo function, prevent induction of a Th2 response in mice challenged with LPS and an experimental harmless airborne antigen. IMs, but not alveolar macrophages, were found to produce high levels of IL-10 and to inhibit LPS-induced maturation and migration of DCs loaded with the experimental harmless airborne antigen in an IL-10-dependent manner. We further demonstrated that specific in vivo elimination of IMs led to overt asthmatic reactions to innocuous airborne antigens inhaled with low doses of LPS. This study has revealed a crucial role for IMs in maintaining immune homeostasis in the respiratory tract and provides an explanation for the paradox that although airborne LPS has the ability to promote the induction of Th2 responses by lung DCs, it does not provoke airway allergy under normal conditions. [less ▲]

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See detailWiskott-Aldrich syndrome protein is required for regulatory T cell homeostasis
Humblet, Stéphanie ULg; Sather, B.; Anover, S. et al

in Journal of Clinical Investigation (2007), 117(2), 407-18

Wiskott-Aldrich syndrome protein (WASp) is essential for optimal T cell activation. Patients with WAS exhibit both immunodeficiency and a marked susceptibility to systemic autoimmunity. We investigated ... [more ▼]

Wiskott-Aldrich syndrome protein (WASp) is essential for optimal T cell activation. Patients with WAS exhibit both immunodeficiency and a marked susceptibility to systemic autoimmunity. We investigated whether alterations in Treg function might explain these paradoxial observations. While WASp-deficient (WASp-/-) mice exibited normal thymic Treg generation, the competitive fitness of peripheral Tregs was severely compromised. The total percentage of forkhead box P3-positive (Foxp3+) Tregs among CD4+T cells was reduced, and WASp-/- Tregs were rapidly outcompeted by WASp+ Tregs in vivo. These findings correlated with reduced expression of markers associated with self-antigen-driven peripheral Treg activation and homing to inflamed tissue. Consistent with these findings, WASp-/- Tregs showed a reduced ability to control aberrant T cell activation and autoimmune pathology in Foxp3-/- Scurfy (sf) mice. Finally, WASp+ Treg exhibited a marked selective advantage in vivo in a WAS patient with a spontaneous revertant mutation, indicating that altered Treg fitness likely explains the autoimmune features in human WAS. [less ▲]

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See detailTracking the recovery of consciousness from coma
Laureys, Steven ULg; Boly, Mélanie ULg; Maquet, Pierre ULg

in Journal of Clinical Investigation (2006), 116(7), 1823-1825

Predicting the chances of recovery of consciousness and communication in patients who survive their coma but transit in a vegetative state or minimally conscious state (MCS) remains a major challenge for ... [more ▼]

Predicting the chances of recovery of consciousness and communication in patients who survive their coma but transit in a vegetative state or minimally conscious state (MCS) remains a major challenge for their medical caregivers. Very few studies have examined the slow neuronal changes underlying functional recovery of consciousness from severe chronic brain damage. A case study in this issue of the JCI reports an extraordinary recovery of functional verbal communication and motor function in a patient who remained in MCS for 19 years (see the related article beginning on page 2005). Diffusion tensor MRI showed increased fractional anisotropy (assumed to reflect myelinated fiber density) in posteromedial cortices, encompassing cuneus and precuneus. These same areas showed increased glucose metabolism as studied by PET scanning, likely reflecting the neuronal regrowth paralleling the patient's clinical recovery. This case shows that old dogmas need to be oppugned, as recovery with meaningful reduction in disability continued in this case for nearly 2 decades after extremely severe traumatic brain injury. [less ▲]

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See detailRevascularization of ischemic tissues by PDGF-CC via effects on endothelial cells and their progenitors
Li, X. R.; Tjwa, M.; Moons, L. et al

in Journal of Clinical Investigation (2005), 115(1), 118-127

The angiogenic mechanism and therapeutic potential of PDGF-CC, a recently discovered member of the VEGF/PDGF superfamily, remain incompletely characterized. Here we report that PDGF-CC mobilized ... [more ▼]

The angiogenic mechanism and therapeutic potential of PDGF-CC, a recently discovered member of the VEGF/PDGF superfamily, remain incompletely characterized. Here we report that PDGF-CC mobilized endothelial progenitor cells in ischemic conditions; induced differentiation of bone marrow cells into ECs; and stimulated migration of ECs. Furthermore, PDGF-CC induced the differentiation of bone marrow cells into smooth muscle cells and stimulated their growth during vessel sprouting. Moreover, delivery of PDGF-CC enhanced postischemic revascularization of the heart and limb. Modulating the activity of PDGF-CC may provide novel opportunities for treating ischemic diseases. [less ▲]

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See detailImpaired neuromuscular transmission and skeletal muscle fiber necrosis in mice lacking Na/Ca exchanger 3
Sokolow, S.; Manto, M.; Gailly, P. et al

in Journal of Clinical Investigation (2004), 113

We produced and analyzed mice deficient for Na/Ca exchanger 3 (NCX3), a protein that mediates cellular Ca(2+) efflux (forward mode) or Ca(2+) influx (reverse mode) and thus controls intracellular Ca(2 ... [more ▼]

We produced and analyzed mice deficient for Na/Ca exchanger 3 (NCX3), a protein that mediates cellular Ca(2+) efflux (forward mode) or Ca(2+) influx (reverse mode) and thus controls intracellular Ca(2+) concentration. NCX3-deficient mice (Ncx3(-/-)) present a skeletal muscle fiber necrosis and a defective neuromuscular transmission, reflecting the absence of NCX3 in the sarcolemma of the muscle fibers and at the neuromuscular junction. The defective neuromuscular transmission is characterized by the presence of electromyographic abnormalities, including low compound muscle action potential amplitude, a decremental response at low-frequency nerve stimulation, an incremental response, and a prominent postexercise facilitation at high-frequency nerve stimulation, as well as neuromuscular blocks. The analysis of quantal transmitter release in Ncx3(-/-) neuromuscular junctions revealed an important facilitation superimposed on the depression of synaptic responses and an elevated delayed release during high-frequency nerve stimulation. It is suggested that Ca(2+) entering nerve terminals is cleared relatively slowly in the absence of NCX3, thereby enhancing residual Ca(2+) and evoked and delayed quantal transmitter release during repetitive nerve stimulation. Our findings indicate that NCX3 plays an important role in vivo in the control of Ca(2+) concentrations in the skeletal muscle fibers and at the neuromuscular junction [less ▲]

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See detailEGF amplifies the replacement of parvalbumin-expressing striatal interneurons after ischemia.
Teramoto, Tetsuyuki; Qiu, Jianhua; Plumier, Jean-Christophe ULg et al

in Journal of Clinical Investigation (2003), 111(8), 1125-32

EGF promotes proliferation and migration of stem/progenitor cells in the normal adult brain. The effect of epidermal growth factor on neurogenesis in ischemic brain is unknown, however. Here we show that ... [more ▼]

EGF promotes proliferation and migration of stem/progenitor cells in the normal adult brain. The effect of epidermal growth factor on neurogenesis in ischemic brain is unknown, however. Here we show that intraventricular administration of EGF and albumin augments 100-fold neuronal replacement in the injured adult mouse striatum after cerebral ischemia. Newly born immature neurons migrate into the ischemic lesion and differentiate into mature parvalbumin-expressing neurons, replacing more than 20% of the interneurons lost by 13 weeks after ischemia and representing 2% of the total BrdU-labeled cells. These data suggest that administration of EGF and albumin could be used to manipulate endogenous neurogenesis in the injured brain and to promote brain self-repair. [less ▲]

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See detailRapid nontranscriptional activation of endothelial nitric oxide synthase mediates increased cerebral blood flow and stroke protection by corticosteroids.
Limbourg, Florian P; Huang, Zhihong; Plumier, Jean-Christophe ULg et al

in Journal of Clinical Investigation (2002), 110(11), 1729-38

Many cellular responses to corticosteroids involve the transcriptional modulation of target genes by the glucocorticoid receptor (GR). A rapid, non-nuclear effect of GR was found to mediate ... [more ▼]

Many cellular responses to corticosteroids involve the transcriptional modulation of target genes by the glucocorticoid receptor (GR). A rapid, non-nuclear effect of GR was found to mediate neuroprotection. High-dose corticosteroids (20 mg/kg intraperitoneally), given within 2 hours of transient cerebral ischemia, acutely increased endothelial nitric oxide synthase (eNOS) activity, augmented regional cerebral blood flow (CBF) by 40% to 50%, and reduced cerebral infarct size by 32%. These neuroprotective effects of corticosteroids were abolished by the GR antagonist RU486 and by inhibition of phosphatidylinositol 3-kinase (PI3K), and were absent in eNOS(-/-) mice. To determine the mechanism by which GR activated eNOS, we measured the effect of corticosteroids on PI3K and the protein kinase Akt. In a ligand-dependent manner, GR activated PI3K and Akt in vitro and in vivo caused NO-dependent vasodilation, which was blocked by cotreatment with RU486 or the PI3K inhibitor LY294002 but not by transcriptional inhibitors. Indeed, a mutant GR, which cannot dimerize and bind to DNA, still activated PI3K and Akt in response to corticosteroids. These findings indicate that non-nuclear GR rapidly activates eNOS through the PI3K/Akt pathway and suggest that this mechanism mediates the acute neuroprotective effects of corticosteroids through augmentation of CBF. [less ▲]

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See detailStromelysin-3 expression promotes tumor take in nude mice
Noël, Agnès ULg; Lefebvre, O.; Maquoi, Erik ULg et al

in Journal of Clinical Investigation (1996), 97

Stromelysin-3 (ST3) is a matrix metalloproteinase expressed in human carcinomas in ways suggesting that it may play a role in tumor progression. To test this possibility, we have performed gene transfer ... [more ▼]

Stromelysin-3 (ST3) is a matrix metalloproteinase expressed in human carcinomas in ways suggesting that it may play a role in tumor progression. To test this possibility, we have performed gene transfer experiments using both anti-sense and sense ST3 expression vectors, and malignant cells either expressing (NIH 3T3 fibroblasts) or not (MCF7 epithelial cells) endogenous ST3. We have compared the ability of parental and transfected cells to cause subcutaneous tumor development in nude mice. 3T3 cells expressing anti-sense ST3 RNA showed reduced tumorigenicity, and MCF7 cells expressing mouse or human ST3 were associated with reduced tumor-free period leading to a significant increased tumor incidence(P<10(-4)). However, once established, the ST3 expressing tumors did not grow faster than those obtained with the parental MCF7 cell line. In addition, tumors obtained after sub-cutaneous injection of ST3-expressing or nonexpressing cells did not exhibit obvious histological differences, and careful examination did not reveal any local invasive tissue areas nor systemic metastases. These in vivo observations were in agreement with those obtained in vitro showing that ST3 expression did not modify proliferative nor invasive properties of transfected cells. Altogether, these results indicate that ST3 expression promotes tumor take in nude mice, presumably by favoring cancer cell survival in a tissue environment initially not permissive for tumor growth. These findings represent the first experimental evidence showing that ST3 can modulate cancer progression. [less ▲]

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See detail24-hour glucose profiles during continuous or oscillatory insulin infusion. Demonstration of the functional significance of ultradian insulin oscillations.
Sturis, J.; Scheen, André ULg; Leproult, R. et al

in Journal of Clinical Investigation (1995), 95(4), 1464-71

Under basal and stimulated conditions, normal insulin secretion oscillates with periods in the ultradian 100-150-min range. To test the hypothesis that oscillatory insulin delivery is more efficient in ... [more ▼]

Under basal and stimulated conditions, normal insulin secretion oscillates with periods in the ultradian 100-150-min range. To test the hypothesis that oscillatory insulin delivery is more efficient in reducing blood glucose levels than continuous administration, nine normal young men were each studied on two occasions during a 28-h period including a period of polygraphically recorded sleep. Endogenous insulin secretion was suppressed by somatostatin, a constant intravenous glucose infusion was administered, and exogenous insulin was infused either at a constant rate or in a sinusoidal pattern with a period of 120 min. The mean glucose level over the 28-h period was 0.72 +/- 0.31 mmol/liter lower when insulin was infused in an oscillatory pattern than when the rate of infusion was constant (P < 0.05). The greater hypoglycemic effect of oscillatory versus constant infusion was particularly marked during the daytime, with the difference averaging 1.04 +/- 0.38 mmol/liter (P < 0.03). Serum insulin levels tended to be lower during oscillatory than constant infusion, although the same amount of exogenous insulin was administered under both conditions. Ultradian insulin oscillations appear to promote more efficient glucose utilization. [less ▲]

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See detailTransgenic mice expressing the human heat shock protein 70 have improved post-ischemic myocardial recovery.
Plumier, Jean-Christophe ULg; Ross, B.; Currie, R. W. et al

in Journal of Clinical Investigation (1995), 95(4), 1854-60

Heat shock treatment induces expression of several heat shock proteins and subsequent post-ischemic myocardial protection. Correlations exist between the degree of stress used to induce the heat shock ... [more ▼]

Heat shock treatment induces expression of several heat shock proteins and subsequent post-ischemic myocardial protection. Correlations exist between the degree of stress used to induce the heat shock proteins, the amount of the inducible heat shock protein 70 (HSP70) and the level of myocardial protection. The inducible HSP70 has also been shown to be protective in transfected myogenic cells. Here we examined the role of human inducible HSP70 in transgenic mouse hearts. Overexpression of the human HSP70 does not appear to affect normal protein synthesis or the stress response in transgenic mice compared with nontransgenic mice. After 30 min of ischemia, upon reperfusion, transgenic hearts versus nontransgenic hearts showed significantly improved recovery of contractile force (0.35 +/- 0.08 versus 0.16 +/- 0.05 g, respectively, P < 0.05), rate of contraction, and rate of relaxation. Creatine kinase, an indicator of cellular injury, was released at a high level (67.7 +/- 23.0 U/ml) upon reperfusion from nontransgenic hearts, but not transgenic hearts (1.6 +/- 0.8 U/ml). We conclude that high level constitutive expression of the human inducible HSP70 plays a direct role in the protection of the myocardium from ischemia and reperfusion injury. [less ▲]

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See detailNeuroendocrine Mechanism of Onset of Puberty. Sequential Reduction in Activity of Inhibitory and Facilitatory N-Methyl-D-Aspartate Receptors
Bourguignon, Jean-Pierre ULg; Gerard, Arlette ULg; Alvarez Gonzalez, Maria-Luz ULg et al

in Journal of Clinical Investigation (1992), 90(5), 1736-44

In humans and in several animal species, puberty results from changes in pulsatile gonadotropin-releasing hormone (GnRH) secretion in the hypothalamus. In particular, the frequency of pulsatile GnRH ... [more ▼]

In humans and in several animal species, puberty results from changes in pulsatile gonadotropin-releasing hormone (GnRH) secretion in the hypothalamus. In particular, the frequency of pulsatile GnRH secretion increases at the onset of puberty, as can be shown by using hypothalamic explants of male rats of 15 and 25 d. Previous observations from us and others suggested that the initiation of puberty could involve a facilitatory effect of excitatory amino acids mediated through N-methyl-D-aspartate (NMDA) receptors. We found that GnRH secretion could be activated through NMDA receptors only around the time of onset of puberty (25 d). The aim of this study was to clarify why this activation did not occur earlier (at 15 d) and could no longer be observed by the end of puberty (at 50 d). We studied GnRH secretion in the presence of MK-801, a noncompetitive antagonist of NMDA receptors or AP-5, a competitive antagonist. We showed that, in the hypothalamus of immature male rats (15 d), a highly potent inhibitory control of pulsatile GnRH secretion in vitro was mediated through NMDA receptors. These data were confirmed in vivo because administration of the antagonist MK-801 (0.001 mg/kg) to immature male rats resulted in early pubertal development. Onset of puberty (25 d) was characterized by the disappearance of that NMDA receptor-mediated inhibition, thus unmasking a facilitatory effect also mediated through NMDA receptors. During puberty, there was a reduction in activity of this facilitatory control which was no longer opposed by its inhibitory counterpart. We conclude that a sequential reduction in activity of inhibitory and facilitatory NMDA receptors provides a developmental basis for the neuroendocrine mechanism of onset of puberty. [less ▲]

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See detailRelationship between Whole Plasma Calcitonin Levels, Calcitonin Secretory Capacity, and Plasma Levels of Estrone in Healthy Women and Postmenopausal Osteoporotics
Reginster, Jean-Yves ULg; Deroisy, Rita ULg; Albert, Adelin ULg et al

in Journal of Clinical Investigation (1989), 83(3), 1073-7

The exact role of calcitonin (CT) in the pathogenesis of postmenopausal osteoporosis remains unknown. Whole plasma calcitonin (iCT) basal levels, metabolic clearance rate (MCR), and production rate (PR ... [more ▼]

The exact role of calcitonin (CT) in the pathogenesis of postmenopausal osteoporosis remains unknown. Whole plasma calcitonin (iCT) basal levels, metabolic clearance rate (MCR), and production rate (PR) of CT were measured in 9 premenopausal and 16 postmenopausal women, including 11 osteoporotics (OP). Basal iCT levels were statistically lower in postmenopausal women than in the premenopausal group (P less than 0.01) and strongly correlated (r = 0.72; P less than 0.001) with estrone circulating levels (E1). MCR were similar in all groups. PR were similar in eugonadal women between 22 (mean +/- SD = 30.9 +/- 9.9 micrograms/d) and 37 yr (mean +/- SD = 25.5 +/- 11.1 micrograms/d) premenopausal women. In healthy postmenopausal women PR were reduced, but not significantly (mean +/- SD = 19.5 +/- 6.95 micrograms/d), whereas osteoporotic patients presented a highly significant reduction of CT PR (mean +/- SD = 9.8 +/- 4 micrograms/d) (P less than 0.01). Because there is a strong relationship between E1 and PR (r = 0.64; P less than 0.001), CT secretory capacity appears to be modulated by estrogen circulating levels. This modulation leads to a menopause-related decrease in iCT. In osteoporotics, an independent impairment of CT production drastically lowers PR and basal iCT levels. CT might be one of the determining factors in the pathogenesis of postmenopausal osteoporosis. [less ▲]

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See detailThyroid hormonelike actions of 3,3',5'-L-triiodothyronine nad 3,3'-diiodothyronine
Papavasiliou, S. S.; Martial, Joseph ULg; Latham, K. R. et al

in Journal of Clinical Investigation (1977), 60(6), 1230-9

l-Thyroxine is converted to 3,5,3'-l-triiodothyronine (T(3)) as well as to 3,3',5'-l-triiodothyronine (reverse T(3)). One product of further deiodination is 3,3'-diiodothyronine (3,3'T(2)). The serum ... [more ▼]

l-Thyroxine is converted to 3,5,3'-l-triiodothyronine (T(3)) as well as to 3,3',5'-l-triiodothyronine (reverse T(3)). One product of further deiodination is 3,3'-diiodothyronine (3,3'T(2)). The serum levels of reverse T(3) and 3,3'T(2) change considerably in various physiological and disease states. We previously found that reverse T(3) and 3,3'T(2) bind to the solubilized hepatic nuclear "receptors" for thyroid hormones. This led us to study binding and actions of these metabolites in cultured rat pituitary cells in which glucose consumption and growth hormone production are regulated by T(3) and l-thyroxine.Reverse T(3) and 3,3'T(2) stimulated growth hormone production and glucose consumption and inhibited nuclear binding of radioactive T(3). Either metabolite produced maximal effects that equaled those of T(3), and neither inhibited the T(3) response. Further, additive effects were observed when reverse T(3) was combined with submaximal concentrations of T(3).In serum-free and serum-containing media, concentrations of 3,3'T(2) 50- to 70- and 10- to 100-fold greater, respectively, than those of T(3) were required for equivalent stimulations and for inhibition of nuclear binding by T(3). The relative activity differences under the two conditions can be attributed to weaker serum protein binding of 3,3'T(2) than T(3). With cells in serum-free media, reverse T(3) was a less avid competitor than 3,3'T(2) for T(3) binding by the nuclear receptors, and was less potent than 3,3'T(2) (0.001 the potency of T(3)) in inducing growth hormone production or glucose oxidation. In incubations with serum-containing media, reverse T(3) was an ineffective competitor for T(3) binding, and had only 0.1 the inducing potency of 3,3'T(2) (0.001 the potency of T(3)). The weaker activity of reverse T(3) relative to 3,3'T(2) in serum-containing media could be explained by stronger serum binding of reverse T(3) than 3,3'T(2). In addition, after long-term incubation of cells with radioactive reverse T(3), much of the cell-associated radioactivity was recovered as 3,3'T(2).These studies suggest that reverse T(3) and 3,3'T(2) can stimulate thyroid hormone-regulated functions as weak agonists by acting via the same receptors that mediate T(3) actions. Moreover, some of the effects of reverse T(3) may be due to 3,3'T(2) produced by deiodination of reverse T(3). [less ▲]

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See detailStorage Iron Kinetics. VII. A biologic Model for Reticulo-Endothelial Iron Transport
Fillet, Georges ULg; Cook, J.-D.; Finch, C. A.

in Journal of Clinical Investigation (1974), 53

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes ... [more ▼]

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes labeled with 59Fe and of transferrin-bound 55Fe. The early reticuloendothelial release of iron, a matter of hours, was calculated from the plasma turnover rate of 55Fe and the plasma reappearance of 59Fe. Late release was calculated from the ratio of the cumulative incorporation of both tracers into the circulating red cell mass over a period of 2wk. There was an initial processing period within the reticuloendothelial cell, after which radioiron either rapidly returned to circulation (t 34 min) or was transferred to a slowly exchanging pool of storage iron within the reticuloendothelial cell (t release to plasma of 7 days). These pathways were of equal magnitude in the normal dog. Reticuloendothelial release of iron was largely independent of the pre-existing plasma iron level or transferrin saturation. Diurnal fluctuations in the plasma iron level were shown to be the result of a variable partitioning of iron between the early and late release phases. Acute inflammation resulted in a prompt and marked increase in the fraction of iron stored (late phase), whereas depletion of iron stores resulted in a marked increase in early release. [less ▲]

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