• Altered pharmacological effects of adrenergic agonists during hypothermia 

      Dietrichs, Erik Sveberg; Sager, Georg; Tveita, Torkjel (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-05)
      Rewarming from accidental hypothermia is often complicated by hypothermia-induced cardiac dysfunction, calling for immediate pharmacologic intervention. Studies show that although cardiac pharmacologic support is applied when rewarming these patients, a lack of updated treatment recommendations exist. Mainly due to lack of clinical and experimental data, neither of the international guidelines ...
    • Binding site of ABC transporter homology models confirmed by ABCB1 crystal structure 

      Ravna, Aina W.; Sylte, Ingebrigt; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2009-09-04)
      The human ATP-binding cassette (ABC) transporters ABCB1, ABCC4 and ABCC5 are involved in resistance to chemotherapeutic agents. Here we present molecular models of ABCB1, ABCC4 and ABCC5 by homology based on a wide open inward-facing conformation of <i>Escherichia coli</i> MsbA, which were constructed in order to elucidate differences in the electrostatic and molecular features of their drug ...
    • Data on RT-qPCR assay of nuclear progesterone receptors (nPR), membrane progesterone receptors (mPR) and progesterone receptor membrane components (PGRMC) from human uterine endometrial tissue and cancer cells of the uterine cervix 

      Smaglyukova, Natalia; Sletten, Elise Thoresen; Ørbo, Anne; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-25)
      A previous investigation showed that the endometrium normalized in women with endometrial hyperplasia after three months treatment with high dose levonorgestrel IUS (intrauterine system). The effect was maintained even if immunohistochemical analyses of the endometrium showed that nuclear progesterone receptors (nPRs) were completely downregulated. These observations indicated that some type of ...
    • En pionerforsker 

      Sylte, Ingebrigt; Sager, Georg (Journal article; Tidsskriftartikkel, 2013)
      Professor Svein Dahl ved Universitetet i Tromsø var en framtredende og nyskapende legemiddelforsker. De metodene han benyttet, brukes den dag i dag av farmasøytisk industri og forskere over hele verden.
    • Expression of nuclear progesterone receptors (nPR), membrane progesterone receptors (mPR) and progesterone receptor membrane components (PGRMC) in the human endometrium after 6 months levonorgestrel low dose intrauterine therapy 

      Sletten, Elise Thoresen; Smaglyukova, Natalia; Ørbo, Anne; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-29)
      The classical steroid receptors (nuclear receptors), including those for progesterone (nPRs), are thoroughly characterized. The knowledge about so-called non-genomic effects, which are mediated by extra-nuclear initiated signals, has increased immensely the last decades. In a previous clinical study of endometrial hyperplasia, we observed that the antiproliferative progestin effect persisted after ...
    • Identification and experimental confirmation of novel cGMP efflux inhibitors by virtual ligand screening of vardenafil-analogues 

      Kashgari, Farzane Kuresh; Ravna, Aina Westrheim; Sager, Georg; Lyså, Roy Andre; Enyedy, Istvan; Dietrichs, Erik Sveberg (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-28)
      <i>Background</i> - Clinical studies have reported overexpression of PDE5 and elevation of intracellular cyclic GMP in various types of cancer cells. ABCC5 transports cGMP out of the cells with high affinity. PDE5 inhibitors prevent both cellular metabolism and cGMP efflux by inhibiting ABCC5 as well as PDE5. Increasing intracellular cGMP is hypothesized to promote apoptosis and growth restriction ...
    • Inhibition of ABCC5-mediated cGMP transport by progesterone, testosterone and their analogues 

      Odland, Sondre Ulstein; Ravna, Aina Westrheim; Smaglyukova, Natalia; Dietrichs, Erik Sveberg; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-13)
      The biodynamics and biokinetics of sex hormones are complex. In addition to the classical steroid receptors (nuclear receptors), these hormones act through several non-genomic mechanisms. Modulation of ABC-transporters by progesterone represents a non-genomic mechanism. In the present study, we employed inside out vesicles from human erythrocytes to characterize high affinity cGMP transport by ABCC5 ...
    • Inhibition of PDE5A1 guanosine cyclic monophosphate (cGMP) hydrolysing activity by sildenafil analogues that inhibit cellular cGMP efflux 

      Subbotina, Anna; Ravna, Aina Westrheim; Lyså, Roy Andre; Abagyan, Ruben; Bugno, Ryszard; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-17)
      <p><i>Objectives</i>: To determine the ability of 11 sildenafil analogues to discriminate between cyclic nucleotide phosphodiesterases (cnPDEs) and to characterise their inhibitory potencies (<kursiv>K</kursiv><sub>i</sub> values) of PDE5A1‐dependent guanosine cyclic monophosphate (cGMP) hydrolysis.</p> <p><i>Methods</i>: Sildenafil analogues were identified by virtual ligand screening (VLS) ...
    • Moderate but not severe hypothermia increases intracellular cyclic AMP through preserved production and reduced elimination 

      Kuzmiszyn, Adrina Kalasho; Selli, Anders Lund; Furuholmen, Markus; Smaglyukova, Natalia; Kondratiev, Timofei; Fuskevåg, Ole Martin; Sager, Georg; Dietrichs, Erik Sveberg (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-14)
      Rewarming from accidental hypothermia could be complicated by acute cardiac dysfunction but providing supportive pharmacotherapy at low core temperatures is challenging. Several pharmacological strategies aim to improve cardiovascular function by increasing cAMP in cardiomyocytes as well as cAMP and cGMP levels in vascular smooth muscle, but it is not clear what effects temperature has on cellular ...
    • Modulation of high affinity ATP-dependent cyclic nucleotide transporters by specific and non-specific cyclic nucleotide phosphodiesterase inhibitors 

      Aronsen, Lena; Ørvoll, Elin Peggy Hanne Øien; Lyså, Roy Andre; Ravna, Aina Westrheim; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-11-07)
      Intracellular cyclic nucleotides are eliminated by phosphodiesterases (PDEs) and by ATP Binding cassette transporters such as ABCC4 and ABCC5. PDE5 and ABCC5 have similar affinity for cGMP whereas ABCC5 has much higher affinity for cGMP compared with cAMP. Since the substrate (cGMP) is identical for these two eliminatory processes it is conceivable that various PDE inhibitors also modulate ...
    • Molecular model of the outward facing state of the human P-glycoprotein (ABCB1), and comparison to a model of the human MRP5 (ABCC5) 

      Ravna, Aina W.; Sylte, Ingebrigt; Sager, Georg (Journal article; Tidsskriftartikkel; Peer reviewed, 2007-09-06)
      Background: Multidrug resistance is a particular limitation to cancer chemotherapy, antibiotic treatment and HIV medication. The ABC (ATP binding cassette) transporters human P-glycoprotein (ABCB1) and the human MRP5 (ABCC5) are involved in multidrug resistance. Results: In order to elucidate structural and molecular concepts of multidrug resistance, we have constructed a molecular model of the ...
    • Molecular modeling study of the testosterone metabolizing enzyme UDP-glucuronosyltransferase 2B17 

      Trane, Ingmar; Sager, Georg; Dietrichs, Erik Sveberg; Ravna, Aina Westrheim (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-20)
      The dominant sex hormone testosterone is mainly metabolized by liver enzymes belonging to the uridine-diphospho (UDP) glucuronosyltransferase (UGT) family. These enzymes are the main phase II enzymes, and they have an important role in the detoxification of endogenous and exogenous compounds in humans. The aim of the present study was to improve the understanding of the binding properties of UGT2B17. ...
    • Pharmacodynamic properties for inhibition of cAMP- and cGMP elimination by pentoxifylline remain unaltered in vitro during hypothermia 

      Selli, Anders Lund; Kalasho, Adrina; Smaglyukova, Natalia; Kondratiev, Timofei; Fuskevåg, Ole Martin; Sager, Georg; Dietrichs, Erik Sveberg (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-15)
      Background - Rewarming from hypothermia is associated with severe complications, one of which is hypothermia-induced cardiac dysfunction. This condition is characterized by decreased cardiac output accompanied by increased total peripheral resistance. This contributes to mortality rate approaching 40%. Despite this, no pharmacological interventions are recommended for these patients below 30 °C. ...
    • The role of OAT2 (SLC22A7) in the cyclic nucleotide biokinetics of human erythrocytes 

      Sager, Georg; Smaglyukova, Natalia; Fuskevåg, Ole-Martin (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-15)
    • Sodium nitroprusside inhibits HEK293 cell growth by cGMP-dependent and independent mechanisms 

      Sager, Georg; Sundkvist, Elisabeth; Jæger, Ragnhild; Lyså, Roy Andre; Fuskevåg, Ole-Martin; Fuskevåg, Ole-Martin (Journal article; Tidsskriftartikkel, 2014)
    • Transfer of triptans into human breast milk and estimation of infant drug exposure through breastfeeding 

      Amundsen, Siri; Nordeng, Hedvig; Nordeng, Hedvig Marie Egeland; Fuskevåg, Ole Martin; Nordmo, Elisabet; Nordmo, Elisabet N; Sager, Georg; Spigset, Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-17)
      Clinical data on the transfer of triptans into human breast milk remain scarce. In a lactation study including 19 breastfeeding women with migraine, we examined the excretion of six different triptans into milk. Following intake of a single dose, each participant collected seven breast milk samples at predefined intervals up to 24 hours after dose. Triptan concentrations in milk were measured using ...
    • Treatment of Cardiovascular Dysfunction with PDE3-Inhibitors in Moderate and Severe Hypothermia—Effects on Cellular Elimination of Cyclic Adenosine Monophosphate and Cyclic Guanosine Monophosphate 

      Kuzmiszyn, Adrina Kalasho; Selli, Anders Lund; Smaglyukova, Natalia; Kondratiev, Timofei; Fuskevåg, Ole Martin; Lysaa, Roy A; Ravna, Aina Westrheim; Tveita, Torkjel; Sager, Georg; Dietrichs, Erik Sveberg (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-13)
      <p><b>Introduction:</b> Rewarming from accidental hypothermia is often complicated by hypothermia-induced cardiovascular dysfunction, which could lead to shock. Current guidelines do not recommend any pharmacological treatment at core temperatures below 30°C, due to lack of knowledge. However, previous in vivo studies have shown promising results when using phosphodiesterase 3 (PDE3) inhibitors, ...
    • Treatment of cardiovascular dysfunction with PDE5-inhibitors - temperature dependent effects on transport and metabolism of cAMP and cGMP 

      Selli, Anders Lund; Kuzmiszyn, Adrina Kalasho; Smaglyukova, Natalia; Kondratiev, Timofei V.; Fuskevåg, Ole Martin; Lyså, Roy Andre; Ravna, Aina Westrheim; Tveita, Torkjel; Sager, Georg; Dietrichs, Erik Sveberg (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-30)
      <i>Introduction</i>: Cardiovascular dysfunction is a potentially lethal complication of hypothermia. Due to a knowledge gap, pharmacological interventions are not recommended at core temperatures below 30°C. Yet, further cooling is induced in surgical procedures and survival of accidental hypothermia is reported after rewarming from below 15°C, advocating a need for evidence-based treatment guidelines. ...
    • Vasopressin impairs brain, heart and kidney perfusion: an experimental study in pigs after transient myocardial ischemia 

      Müller, Stig; How, Ole-Jakob; Hermansen, Stig Eggen; Stenberg, Thor Allan; Sager, Georg; Myrmel, Truls (Journal article; Tidsskriftartikkel; Peer reviewed, 2008-02-21)
      Introduction: Arginine vasopressin (AVP) is increasingly used to restore mean arterial pressure (MAP) in low-pressure shock states unresponsive to conventional inotropes. This is potentially deleterious since AVP is also known to reduce cardiac output by increasing vascular resistance. The effects of AVP on blood flow to vital organs and cardiac performance in a circulation altered by cardiac ...