In Vitro Interaction of Tetrahydrouridine with Key Human Nucleoside Transporters.

NDec is a novel combination of oral decitabine and tetrahydrouridine that is currently under clinical development for the treatment of sickle cell disease (SCD). Here, we investigate the potential for the tetrahydrouridine component of NDec to act as an inhibitor or substrate of key concentrative nucleoside transporters (CNT1-3) and equilibrative nucleoside transporters (ENT1-2). Nucleoside transporter inhibition and tetrahydrouridine accumulation assays were performed using Madin-Darby canine kidney strain II (MDCKII) cells overexpressing human CNT1, CNT2, CNT3, ENT1, and ENT2 transporters.

Mechanisms and therapeutic potential of inhibiting drug efflux transporters.

Introduction: The ATP-binding cassette transporters are among the largest transmembrane protein families in humans and are expressed in a wide variety of tissues. By promoting outward transport, they protect cells from the accumulation of undesirable substrates. This protection might lead to suboptimal concentration of chemotherapeutics in the tumor cells, resulting in therapy resistance and poor disease prognosis.

Effects of nociceptin and nocistatin on uterine contraction.

The presence and effects of nociceptin (N/OFQ) and nocistatin (NST) in the central nervous system have been reasonably well described, but less data are available on their peripheral functions. Besides their presence in several peripheral organs (white blood cells, airway, liver, skin, vascular and intestinal smooth muscles, ovary, and testis), they have been found in the pregnant myometrium in both rat and human. The level of their precursor prepronociceptin is elevated in the preterm human myometrium as compared with full-term samples, whereas it gradually increases toward term in the pregnant rat uterus.

Nocistatin inhibits pregnant rat uterine contractions in vitro: roles of calcitonin gene-related peptide and calcium-dependent potassium channel.

The endogenous neuropeptide nociceptin/orphanin FQ, translated from the prepronociceptin gene, exerts a contraction-inhibitory effect on the rat uterus. As nocistatin has been reported to cause functional antagonism of the pro-nociceptive effects of nociceptin, we set out to investigate its effects on the pregnant rat uterus and to elucidate its signalling pathway. The expression of prepronociceptin mRNA in the uterus and nocistatin levels in the uterus and the plasma were confirmed by RT-PCR and radioimmunoassay.

Uterus-relaxing effect of β2-agonists in combination with phosphodiesterase inhibitors: studies on pregnant rat in vivo and on pregnant human myometrium in vitro.

Aims: Our aims were to examine the effects of a simultaneous stimulation of β(2) -adrenergic receptors and inhibition of uterine phosphodiesterases (PDE), in the pregnant rat uterus in vivo and on human uterine tissue in vitro. We also set out to measure cAMP levels and detect the expressions of the isoenzymes PDE4B and PDE4D in human uterine tissue samples.

Material And Methods: Preterm birth was induced in Sprague-Dawley rats with bacterial lipopolysaccharide.

Small molecule AKAP-protein kinase A (PKA) interaction disruptors that activate PKA interfere with compartmentalized cAMP signaling in cardiac myocytes.

A-kinase anchoring proteins (AKAPs) tether protein kinase A (PKA) and other signaling proteins to defined intracellular sites, thereby establishing compartmentalized cAMP signaling. AKAP-PKA interactions play key roles in various cellular processes, including the regulation of cardiac myocyte contractility. We discovered small molecules, 3,3'-diamino-4,4'-dihydroxydiphenylmethane (FMP-API-1) and its derivatives, which inhibit AKAP-PKA interactions in vitro and in cultured cardiac myocytes.

Improving the relaxing effect of terbutaline with phosphodiesterase inhibitors: studies on pregnant rat uteri in vitro.

Aims: Previous results by our group showed that the in vitro uterus-relaxing potency of β(2)-adrenergic receptor (β(2)-AR) agonists and uterine cAMP accumulation are enhanced in case of visceral inflammation. Our aim was to study the effects of the non-selective phosphodiesterase (PDE) inhibitor theophylline and the selective PDE4 inhibitor rolipram on the uteri of intact late-pregnant female rats (on days 20 and 22 of pregnancy) and of pregnant rats treated with lipopolysaccharide (LPS) to evoke preterm labor (on day 20).

Main Methods: The effects of theophylline and rolipram alone and of rolipram with terbutaline were investigated in isolated organ system.

Cardioprotective effects of growth hormone-releasing hormone agonist after myocardial infarction.

Whether the growth hormone (GH)/insulin-like growth factor 1(IGF-1) axis exerts cardioprotective effects remains controversial; and the underlying mechanism(s) for such actions are unclear. Here we tested the hypothesis that growth hormone-releasing hormone (GHRH) directly activates cellular reparative mechanisms within the injured heart, in a GH/IGF-1 independent fashion. After experimental myocardial infarction (MI), rats were randomly assigned to receive, during a 4-week period, either placebo (n = 14), rat recombinant GH (n = 8) or JI-38 (n = 8; 50 microg/kg per day), a potent GHRH agonist.

[The effect of the ARC 239 on the myometrial and cervical action in the rat, in vitro].

The premature labour is one of the major challenges in the clinical practice. Finding new agents and mechanisms in the control of uterine activity is the main objective of the last decade's experiments. One of the new targets is the alpha2-adrenoceptors (alpha2-AR).

Progesterone decreases the relaxing effect of the beta3-adrenergic receptor agonist BRL 37344 in the pregnant rat myometrium.

Although the published results regarding the function of the beta(3)-adrenergic receptors (beta(3)-ARs) in the regulation of smooth muscle activity are very promising, the question of the mechanism of beta(3)-ARs' action in the pregnant myometrium cannot be fully answered by human investigations. To assess whether it possesses an essential role in the regulation of uterine contractility in pregnant rats, as in humans, we performed functional, western blotting and molecular biology experiments on the late-pregnant rat myometrium. The influence of progesterone on the function of the beta(3)-ARs was also investigated.

The roles of alpha2-adrenoceptor subtypes in the control of cervical resistance in the late-pregnant rat.

The roles of the alpha(2)-adrenoceptor subtypes in the regulation of cervical resistance have previously not been investigated. The aim of the present study was to identify these receptors in the late-pregnant cervix and determine their functions in vitro in the rat. The expressions of the alpha(2)-adrenoceptor subtypes were determined by means of RT-PCR and Western blotting techniques.

Inflammatory processes enhance cAMP-mediated uterus relaxation in the pregnant rat: the role of TNF-alpha.

The objective of this study was to assess the in vitro uterus relaxing potency of beta(2)-adrenergic receptor (beta(2)-AR) agonists in pregnant rats after in utero administration of the bacterial lipopolysaccharide, Escherichia coli endotoxin (LPS). The LPS (100 microg/kg) was injected into the uterine lumen on day 16 of pregnancy. The effects of beta(2)-AR agonist terbutaline was tested in vitro, in isolated uterine rings precontracted by electric field stimulation.

Different roles of alpha2-adrenoceptor subtypes in non-pregnant and late-pregnant uterine contractility in vitro in the rat.

The roles of the alpha2-adrenoceptor (alpha2-AR) subtypes (alpha2A-, alpha2B- and alpha2C-AR) in uterine contractility have not been investigated. The aims of this study were to identify these receptors in the non-pregnant and the late-pregnant rat myometrium and to determine their roles in contractions. We found that the myometrial alpha2-AR subtypes are involved differently in the control of late-pregnant contractions, while they have no influence on the contractions of the non-pregnant myometrium.

Beta 2-agonist treatment enhances uterine oxytocin receptor mRNA expression in pregnant rats.

The objective of this study was to disclose an interaction between Beta(2)-adrenergic (Beta(2)-ARs) and oxytocin (OT) receptors (OTRs) in the late-pregnant rat uterus. We investigated the level of uterine OTR mRNA expression after the administration of Beta(2)-AR agonists fenoterol and hexoprenaline to rats from day 18 to 22 of pregnancy, and also tested the effect of fenoterol on uterine explants. Hexoprenaline induced a maximum 24% increase of OTR mRNA.

Role of capsaicin-sensitive nerve fibers in uterine contractility in the rat.

The possible participation of capsaicin-sensitive sensory nerves in the modulation of neurogenic contractions was studied in nonpregnant and term pregnant rat uteri. Neurogenic contractions were elicited by electric field stimulation (40 V, 1-70 Hz, 0.6 msec) in intact uteri and uteri that were previously exposed to capsaicin in vitro.

Functional and histochemical characterization of a uterine adrenergic denervation process in pregnant rats.

The time course of pregnancy-induced changes in the contractile responses of isolated uterine rings and sympathetic innervation pattern were studied using electric field stimulation and histofluorescence techniques, respectively, in intact and 6-hydroxydopamine-treated rats. Neurally mediated contractions elicited by field stimulation (0.6 msec, 1-70 Hz, 40 V) were measured in uterine preparations obtained from nonpregnant, 6-hydroxydopamine-treated and 5-, 10-, 15-, 18-, and 22-day (term) pregnant rats.