Datac: A multipurpose biological data analysis program based on a mathematical interpreter

doi:10.1016/0020-7101(86)90016-4

International Journal of Bio-Medical Computing

Volume 18, Issues 3–4, May 1986, Pages 193-202

International Journa...

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Abstract

The use of a mathematical command interpreter combined with the structural facility of the C-language allowed us to design a data treatment program having considerable flexibility and being able to handle any types of data (electrophysiological, biochemical and theoretical data). Ensembles of data are treated by the interpreter as if they were simple variables so that an elaborate computation can be performed on the spot by simply writing the appropriate equation on the terminal. These facilities combined with the ability of editing macrocommands at run time provide the user with data treatment possibilities that extends far beyond the possibilities actually implemented in the program. The originality of this program is that the user can easily implement the commands he most often needs, writing them in a language that most scientists will know, algebra.

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The functional pharmacology of receptors composed of the chicken brain GABA_A receptor γ4 subunit and the mammalian GABA_A receptor α3 and β2 subunits was studied by heterologous expression in Xenopus laevis oocytes using the two electrode voltage-clamp technique. GABA-evoked currents had an EC₅₀ of 180±30 μM. Responses were blocked by the competitive and non-competitive GABA_A receptor antagonists, bicuculline methochloride and picrotoxin. Sodium pentobarbital reversibly potentiated the current several-fold, and Zn²⁺ ions blocked the current with high potency (IC₅₀=20 μM). GABA-evoked currents were potentiated by the benzodiazepine site full agonists flunitrazepam and triazolam and less by the partial agonists abecarnil and bretazenil. The inverse agonists methyl-β-carboline-3-carboxylate (β-CCM) and methyl 6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate (DMCM) reduced the current. However, the imidazobenzodiazepine Ro 15-4513, which acts as an inverse agonist at mammalian αxβyγ2 GABA_A receptors (where x=1, 2, 3 or 5, and y=1, 2 or 3), acted as a positive agonist at the γ4 subunit-containing receptors.
Vasopressin potentiation of the melatonin synthetic pathway via specific V<inf>1a</inf> receptors in the rat pineal gland
1996, Regulatory Peptides
The pineal gland releases the ‘time-keeping’ hormone melatonin following a rhythmic sympathetic input which translates light information. The aim of this work was to study the role and mechanisms of action of the central vasopressinergic input on pineal cAMP-dependent melatonin synthesis in the rat. The pineal was found to display vasopressin receptors of the V_1a subtype, as the V_1a antagonist [¹²⁵I]HO-LVA bound in a saturable manner to pineal membranes with a high affinity (k_d = 10 pM) and a maximal binding capacity (B_max) of 13 fmol/mg protein. Vasopressin was able to displace [¹²⁵I]HO-LVA binding in a dose-dependent manner (k_i = 1.9 nM). Vasopressin had no effect on the basal cAMP level and melatonin secretion in cultured rat pinealocytes. However, it clearly and dose-dependently (EC₅₀ = 7 nM) potentiated by 2–3 times cAMP accumulation and by 1.5–2.5 times melatonin secretion induced by moderate noradrenergic stimulation. On strongly stimulated pinealocytes, however, vasopressin could potentiate cAMP accumulation, but not melatonin secretion. The potentiatory effect of vasopressin was inhibited in the presence of the V_1a antagonist. These results indicate that vasopressin is a potent modulator of rat pineal synthetic activity.
Stable expression and pharmacological properties of the human α<inf>7</inf> nicotinic acetylcholine receptor
1995, European Journal of Pharmacology: Molecular Pharmacology
The α₇ neuronal nicotinic acetylcholine receptor subtype forms a Ca²⁺-permeable homooligomeric ion channel sensitive to α-bungarotoxin in Xenopus oocytes. In this study, we have stably and functionally expressed the human α₇ cDNA in a mammalian cell line, HEK-293 and examined its pharmacologic properties. [¹²⁵I]α-Bungarotoxin bound to transfected cellswith a K_d value of 0.7 nM and a B_max value of 973 pmol/mg protein. No specific binding was detected in untransfected cells. Specific binding could be displaced by unlabeled α-bungarotoxin (K_i = 0.5 nM and an excellent correlation was observed between binding affinities of a series of nicotinic cholinergic ligands in transfected cells and those in the human neuroblastoma IMR-32 cell line. Additionally, cell surface expression of α₇ receptors was detected by fluorescein isothiocyanate-conjugated α-bungarotoxin in transfected cells. Whole cell currents sensitive to blockade by α-bungarotoxin, and with fast kinetics of activation and inactivation, were recorded from transfected cells upon rapid application of (−)-nicotine or acetylcholine with EC₅₀ values of 49 μM and 155 μM respectively. We conclude that the human α₇ subunit when expressed alone can form functional ion channels and that the stably transfected HEK-293 cell line serves as a unique system for studying human μ₇ nicotinic receptor function and regulation, and for examining ligand interactions.
Functional expression of nicotinic acetylcholine receptors containing rat α7 subunits in human SH-SY5Y neuroblastoma cells
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Neuronal nicotinic acetylcholine receptors (nAChR) are made from different combinations of subunits encoded by a diverse family of genes. However, the recently cloned α7 gene codes for subunits that can form homooligomeric nAChR complexes when expressed in Xenopus oocytes. Electrophysiological studies reveal that these α7-nAChR function as α-bungarotoxin (Bgt)-sensitive, quickly activating/inactivating ion channels with a unique pharmacological profile and an unusually high permeability to calcium ions. Although similar observations have been made in studies of Bgt-sensitive, functional nAChR subtypes that are naturally expressed in neuronal cells, all attempts until now to reconstitute functional α7-nAChR in cell lines have failed. Here we report the successful use of SH-SY5Y human neuroblastoma cells, which naturally express low levels of endogenous α7 transcripts, to stably overexpress heterologous rat nAChR α7 transgenes. These transgenes are expressed as the appropriately-sized α7 messages and protein, and stably transfected SH-SY5Y cells have over 30-times higher levels of specific Bgt binding sites than do wild-type cells. Whole cell current recordings confirm that transfected cells express functional nAChR that are sensitive to blockade by Bgt and display the typical physiological and pharmacological profiles of α7-nAChR. We conclude that stable, functional expression of α7 transgenes in a mammalian cell line has been achieved for the first time.
Methyl lycaconitine: A novel nicotinic antagonist
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Methyllycaconitine (MLA), a natural toxin from Delphinium seeds, was investigated for its ability to antagonize nicotinic responses in several preparations representing different subtypes of neuronal nicotinic acetylcholine receptor. A presynaptic nicotinic receptor mediating dopamine release from rat striatal synaptosomes was blocked by 10 μM MLA, in good agreement with its Ki of 4 μM for inhibition of [³H]nicotine binding to striatal membranes. Nicotinic responses in rat superior cervical ganglia were similarly blocked by MLA, and this inhibition was readily reversible. Functional expression of the chick α3nα1 and α4nα1 receptor subtypes in Xenopus oocytes confirmed that MLA is a nicotinic antagonist at both receptor subtypes, with IC₅₀ values of 0.08 and 0.65 μM, respectively. Inhibition by MLA was voltage independent and competitive with agonist concentration. Thus MLA is a useful addition to the nicotinic pharmacopoeia.
Electrophysiology of Neuronal Nicotinic Acetylcholine Receptors Expressed in Xenopus Oocytes following Nuclear Injection of Genes or cDNAs
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This chapter presents an overview of electrophysiology of neuronal nicotinic acetylcholine receptors (nAChR) expressed in Xenopus oocytes following nuclear injection of genes or cDNAs. The Xenopus oocyte system allows testing the functions of the many neuronal nAChR-related subunits isolated by molecular cloning. In vivo, some brain nuclei and peripheral nervous system ganglia contain many different species of nAChR-related subunit mRNAs and may, therefore, simultaneously express several neuronal nAChR subtypes. Moreover, there is molecular and physiological evidence that some of the neuronal subunits that have been isolated do not assemble into conventional nAChRs at all. Thus, injecting oocytes with defined pairs of cloned subunit cRNAs or cDNAs is the only direct and rapid way to determine which pairs of subunits assemble into functional receptors and which do not, and what the detailed electrophysiological properties of the various reconstituted receptors are.

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Datac: A multipurpose biological data analysis program based on a mathematical interpreter

Abstract

Brain Res.

Fitting curves to data, the simplex algorithm is the answer

Byte