The Frequency-Dependent Effect of Infrasound on Bull Sperm Velocity Baghdasaryan N, Ayrapetyan S
UNESCO Chair-Life Sciences International Postgraduate Educational Center, Yerevan, Armenia
Background:The rheotaxic properties of sperm indicate the existence of specialized mechano-sensors in sperm membrane detecting the flow direction of the ejaculate. Therefore it is suggested that these sensors could serve as one of targets for infrasound (IS) effect and would have sensitivity to IS frequency. The overall aim of the present work was to study the frequency-dependent effect of 30dB IS on sperm velocity, 45Ca uptake and intracellular level of c-AMP and c-GMP.
Methods: Experiments were performed on preliminary frozen bull sperm incubated in 2.9% Na-citrate water solution at 30oC. IS treatment of sperm samples was done by means of IS waves generating by a special setup. 45Ca-uptake and intracellular cyclic nucleotides contents (cAMP and cGMP) were measured by Wallac 1450 liquid scintillation counter. The sperm velocity was recorded by means of digital video camera (SONY, Japan) set on biological microscope MB-14B connected to PC and sperm direct velocity was estimated by Pinnacle studio program.
Results: It was shown that 2Hz, 30dB 5min IS treatment caused the pronounced elevation effect (25%, ***: p<0.001) on the sperm velocity (Figure 1), which was accompanied by decreasing of intracellular level of c-GMP by 260.7% (*: p<0.05), and increasing of intracellular level of c-AMP 43.57% (*: p<0.05) and 45Ca-uptake 2856% (*: p<0.05) by sperm.
Fig 1. The effect of 1-10 Hz 30dB IS on bull sperm velocity. *: p<0.05; **: p<0.01; ***: p<0.001
Conclusions: The 2Hz, 30dB IS 5min pretreatment caused: 1) activation of sperm velocity; 2) increase of 45Ca uptake, 3) increase of intracellular contents of cAMP and decrease of cGMP.
Synergistic Action of Resveratrol and its Polyhydroxylated Derivative with Cytarabine in HL-60 Human Promyelocytic Leukemia Cells BAGO-HORVATHZS1, SAIKO P1, MURIAS M2, ERKER T2, HANDLER N2, MADLENER S3, JAEGER W2, GRUSCH M4, FRITZER-SZEKERES M1, KRUPITZA G3, SZEKERES T1 1Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Austria, 2Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Austria, 3Institute of Clinical Pathology, Medical University of Vienna, Austria and 4Department of Medicine I, Institute of Cancer Research, Medical University of Vienna, Austria
Background: Resveratrol, a naturally occurring stilbene derivative, is a potent free radical scavenger exerting a multitude of biochemical and antineoplastic effects. Resveratrol was identified as an inhibitor of ribonucleotide reductase (RR), a key enzyme of DNA synthesis and an excellent target of cancer chemotherapy. Inhibitors of RR have been previously shown to exert synergistic combination effects with cytarabine, a well-established antileukemic agent. We investigated the biochemical effects of resveratrol and its polyhydroxylated derivative, 3,3’,4,4’,5,5’-hexahydroxystilbene (M8) on the in situ RR activity, cell cycle distribution, induction of apoptosis and inhibition of NF-kappaB. Furthermore, it was tested whether a combination of resveratrol or M8 with cytarabine could yield synergistic cytotoxic and apoptotic effects in human HL-60 promyelocytic leukemia cells.
Methods:Cytotoxic effects of resveratrol, M8 and cytarabine alone and in combination were analyzed using growth inhibition and clonogenic assays. Synergistic combination effects were identified by the Calcusyn software. In situ inhibition of RR was determined by the incorporation of 14C-labelled cytidine into the DNA of resveratrol-treated HL-60 cells. Concentration of NTPs and dNTPs was measured by a HPLC method. Induction of apoptosis was studied using a Hoechst/propidium iodide staining method. Inhibition of TNF-alpha induced activation of NF-kappaB was shown by EIA and Western blotting and cell cycle distribution was analyzed by FACS.
Results: Resveratrol effectively inhibited incorporation of 14C-labelled cytidine into DNA. Furthermore, incubation of HL-60 cells with resveratrol significantly decreased intracellular dCTP, dTTP, dATP and dGTP concentrations. M8 depleted intracellular NTP pools and dTTP as well as dATP pools. Moreover, M8 inhibited the activation of NF-kappaB and arrested HL-60 cells in the S-phase of the cell cycle. Based on these results, we investigated the combination effects of resveratrol and M8 with cytarabine. In growth inhibition, apoptosis and clonogenic assays, resveratrol and M8 acted synergistically with cytarabine in HL-60 cells.
Conclusions: Based on the synergistic cytotoxic and pro-apoptotic effects, the combination of cytarabine with resveratrol or M8 could become a viable option in the chemotherapy of leukemia and therefore deserves further testing.
The action of a new drug that targets a cancer’s blood supply: the story of DMXAA (ASA404) BAGULEY BC Auckland Cancer Society Research Centre, the University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
DMXAA (ASA404; 5,6-dimethylxanthenone-4-acetic acid), developed in this laboratory [1,2], is currently undergoing Phase III clinical trial, in combination with the cytotoxic drugs carboplatin and paclitaxel, in patients with non small cell lung cancer. DMXAA was originally developed as the most active member of a series of analogues of the drug flavone acetic acid [3]. DMXAA has both a direct, early effect on tumour blood vessels, leading to inhibition of tumour blood flow, and a later effect that is mediated by local release of cytokines and other vasoactive molecules. It is this double action that maintains a sufficiently long duration of tumour blood flow arrest to induce irreversible damage and vascular collapse [1]. The effect DMXAA on tumour vascular endothelial cells appears to be mediated by p38 MAP kinase but the signalling pathway in tumour macrophages that leads to increased production of cytokines has not yet been identified. DMXAA facilitates a positive feedback loop where cytokines from tumour macrophages reduce blood flow and the resulting tissue hypoxia activates macrophages. The clinical antitumour activity of DMXAA is improved by co-administration of cytotoxic drugs and recent experimental results suggest that cytotoxic drugs can activate tumour macrophages through toll-like receptors such as TLR4. Thus, the potential antitumour activity of tumour macrophages may be increase firstly by DMXAA itself, secondly by hypoxia and thirdly by cytotoxic drugs. Studies with DMXAA may not only provide a basis for improved clinical therapy but also facilitate understanding of host events involved in the tumour response.
1. Baguley BC. Antivascular therapy of cancer: DMXAA. The Lancet Oncology 2003, 4, 141-148.
Background: Intestinal drug metabolism and carrier-mediated drug transport are accredited as fundamental factors affecting systemic drug availability. This presentation will initially review inactivation of CYP3A4 by grapefruit, Seville orange, lime and pummelo juices and increased drug bioavailability. The focus will be recent findings of inhibition of OATP1A2 mediated drug uptake by grapefruit, orange and apple juices and decreased absorption.
Methods: A series of in vitro and clinical pharmacokinetic studies were conducted.
Results: OATP1A2 was expressed in healthy human small intestine and co-localized with efflux transporter, MDR1 (P-glycoprotein), to the apical membrane of enterocytes. OATP1A2 was the only shown uptake transporter of the antihistamine, fexofenadine, which is also a substrate for MDR1. Grapefruit and orange juices at 0.5% normal strength halved the in vitro activity of OATP1A2. These juices at 10-fold higher concentration produced much less in vitro inhibition of MDR1, demonstrating potent and preferential in vitro inhibition of OATP1A2. Clinically, grapefruit and orange juice at high volume (1200 ml) markedly decreased oral fexofenadine bioavailability to 30% of that compared to water. Grapefruit juice consumed at a normal volume (300 ml) halved systemic fexofenadine availability consistent with a mechanism involving selective direct inhibition of intestinal OATP1A2. The major flavonoids in grapefruit and orange juice, respectively naringin and hesperidin, caused concentration-dependent in vitro inhibition of OATP1A2. The IC50 for naringin of 3.6 M was several hundred-fold lower than that producing equal inhibition of MDR1. An aqueous solution of naringin (300 ml) at the same concentration as that measured in the tested grapefruit juice (1200 M) decreased fexofenadine bioavailability to 75% of that with water, which accounted for half the reduction observed with grapefruit juice.
Conclusions: These results support a new mechanism of food-drug interactions. The fact that naringin was clinically active substance likely represented the first report of a single dietary ingredient producing a drug interaction in humans by modulating drug transport activity. This type of interaction appears relevant to a range of medications, particularly for those drugs that are essential for treatment of serious medical conditions.
