Nociceptin: an endogenous agonist for central opioid like1 (ORL1) receptors possesses systemic vasorelaxant properties

The purpose of the present study was to investigate the effects of nociceptin on peripheral arterial rings from the cat. When feline renal, mesenteric, carotid and femoral rings with intact endothelium were precontracted with phenylephrine (100 nanomolar), nociceptin (3 x 10(-11)-3 x 10(-6) M) decreased tension in a concentration-dependent manner. The present data suggest nociceptin possesses biologic activity outside the CNS and may contribute to the regulation of systemic blood pressure and regional blood flow.

Direct-Method Structure Determination of the Native Azurin II Protein Using One-Wavelength Anomalous Scattering Data

The one-wavelength anomalous scattering (OAS) X-ray diffraction data of azurin II, a copper-containing protein from Alcaligenes xylosoxidans were collected at the Photon Factory, Japan at a 'routine' wavelength of 0.97 A. The structure had been originally solved by the molecular-replacement method [Dodd, Hasnain, Abraham, Eady & Smith (1995). Acta Cryst. D51, 1052-1064]. As a technique of ab initio structure determination, the direct method [Fan, Hao, Gu, Qian, Zheng & Ke (1990). Acta Cryst. A46, 935-939] was attempted to break the phase ambiguity intrinsic to OAS data. The phases were then improved using the solvent-flattening method. The final electron-density map clearly shows most Calpha positions and many side chains and it is traceable without prior knowledge of the structure. It is concluded that the direct method is capable of phasing anomalous scattering data collected at one wavelength from moderate-sized native proteins (M(w) approximately 20 kDa) which contain copper or atoms with a similar scattering power.

Aggregation of phospholipid vesicles induced by the ribosome inactivating protein saporin

Saporin-S6(SO-6) is a single chain ribosome inactivating protein, which can inhibit protein synthesis by inactivating eukaryotic ribosomes. The interaction of SO-6 with phospholipid model systems was described. SO-6 can specifically interact with negatively-charged phospholipid vesicles and it induces the aggregation of the lipid vesicles. The kinetics of the vesicle aggregation induced by SO-6 was studied. The saturating protein/lipid molar ratio was determined to be 1:100 based on titration experiments. The aggregation is dependent on the temperature in a range that was many times higher than the phase transition temperature of the phospholipid. The effect of pH on the aggregation of the vesicles can not be explained by simple deprotonation of side chain amino groups of the protein, and may be related to conformational changes of the protein. The maintenance of physiological ionic strength was required for the aggregation of SO-6 with vesicles. Finally, the interaction was prompted by Ca2+ ions, and was totally inhibited by EDTA, which suggests that SO-6 may interact with phospholipid vesicles in a Ca(2+)-dependent manner.

Adrenotensin: an adrenomedullin gene product contracts pulmonary blood vessels

The purpose of the present study was to determine the effects of adrenotensin, a newly described product of the ADM gene, on cat pulmonary arterial (PA) rings. Under resting conditions, adrenotensin increased tension of PA rings in a concentration-dependent manner. Although addition of diphenhydramine, ONO-3708, phentolamine, methysergide, atropine, and meclofenamate did not alter the contractile response to adrenotensin, removal of the endothelial cell layer significantly reduced this response. Moreover, precontraction of PA rings with adrenotensin selectively attenuated the pulmonary vasorelaxant response to ADM but not to other vasodilator substances, including isoproterenol, pinacidil, nifedipine, and adenosine. The present data suggest that adrenotensin acts in an endothelium-dependent manner to contract PA rings. Moreover, the present data suggest that adrenotensin may act in a modulatory manner to influence vasorelaxation in response to ADM, a sister proADM product.

Structure Solution of Azurin II from Alcaligenes xylosoxidans using the Laue Method: Possibility of Studying In Situ Redox Changes using X-rays

We have recently demonstrated that X-rays can be used for changing the redox states of the metal centre in metalloproteins [Murphy et al. (1995). J. Synchrotron Rad. 2, 64-69]. The possibility of using the Laue method for studying the structural changes associated with such X-ray-induced reactions is explored by applying the method to the structure determination of a new azurin (hereafter referred to as azurin II) from the denitrifying bacterium Alcaligenes xylosoxidans. Laue X-ray diffraction data of azurin II were collected at station 9.7 of the SRS Daresbury. Three diffraction patterns were recorded on film packs at three different crystal orientations. The data were processed using the Daresbury Laue Software Suite to give 2224 independent single reflections (R(merge) = 0.136) in the wavelength range 0.36-1.40 A. The data completeness was 44% at 2.55 A resolution. Phase determination for the data was undertaken using the molecular-replacement method; the top peak was chosen in both the rotation function and the subsequent translation function. This solution agreed well with the molecular-replacement solution achieved independently using monochromatic data. The electron-density map showed reasonably good agreement with the model and the copper site was readily recognizable as it had the highest density. To see if the electron-density map could be improved, ;the doublets in the diffraction data were then deconvoluted. This added 26% data in the region infinity-2d(min) resulting in an improvement in the data completeness to 50% and thus in improved continuity of the electron-density map. The quality of these maps is discussed from the point of view of the suitability of this approach for studying redox-induced structural changes.

Angiotensin induction of PAI-1 expression in endothelial cells is mediated by the hexapeptide angiotensin IV

Recent studies from this laboratory have demonstrated that angiotensin II (Ang II) stimulates the expression of plasminogen activator inhibitor 1 (PAI-1) in cultured endothelial cells. This response does not appear to be mediated via an interaction with either the AT1 or the AT2 receptor subtype. Since a novel angiotensin receptor has been identified in a variety of tissues that specifically binds the hexapeptide Ang IV (Ang II, [3-8]), we therefore examined the effects of Ang IV on the expression of PAI-1 mRNA in bovine aortic endothelial cells. Ang IV stimulated dose- and time-dependent increases in the expression of PAI-1 mRNA. The effect of Ang IV (10 nM) was not inhibited by Dup 753 (1.0 microM), a highly specific antagonist of the AT1 receptor, or by PD123177 (1.0 microM), a highly specific antagonist of the AT2 receptor. In contrast, the AT4 receptor antagonist, WSU1291 (1.0 microM), effectively prevented PAI-1 expression. Although larger forms of angiotensin (i.e., Ang I, Ang II, and Ang III) are capable of inducing PAI-1 expression, this property is lost in the presence of converting enzyme or aminopeptidase inhibitors. These results indicate that the hexapeptide Ang IV is the form of angiotensin that stimulates endothelial expression of PAI-1. This effect appears to be mediated via the stimulation of an endothelial receptor that is specific for Ang IV.

The Laue Data Module (LDM) – a software development for Laue X-ray diffraction data processing

The Laue Data Module (LDM) has been defined and implemented in Fortran as the basis for new developments in the processing of Laue X-ray diffraction data. It provides a program-independent way of handling, storing and accessing the parameters required in the initial stages of Laue data processing. The program-independent Laue Reflection List (LRL) and associated functions have also been developed. The way in which these two developments may be used in application programs and as the basis for developing further program-independent Laue-data processing functions is described.

Agmatine: a novel endogenous vasodilator substance

The purpose of the study was to investigate the effects of agmatine, an endogenous clonidine-displacing substance (CDS), on systemic hemodynamics in the anesthetized rat. Bolus intravenous (i.v.) injections of agmatine decreased systemic arterial pressure (SAP) and systemic vascular resistance in a dose-dependent manner. The development of acute tachyphylaxis to the systemic vasodepressor response to agmatine did not induce cross-tachyphylaxis to the systemic vasodepressor responses to bradykinin, isoproterenol and nitroglycerin. The present data demonstrate agmatine, as a CDS and agonist for imidazoline (I) receptors, possesses marked systemic vasodilator activity in the rat. The present data suggest that activation of I receptors may represent a novel mechanism of vasodilation in vivo.

Fluorescence spectroscopic study of the interaction of adenine and nucleotide with trichosanthin

Trichosanthin (TCS) is an N-glycosidase that can attack the 28s rRNA of the ribosome at a highly conserved adenine residue. The interactions of adenine and its derivative nucleotides with TCS are reported. The fluorescence of Trp 192 of TCS is sensitive to the proximity of adenine, and produces a marked red shift indicative of trytophan in a more hydrophilic environment. By contrast AMP and ATP quench the maximal emission at 328nm. The binding of the adenine and ATP with TCS result in lower tryptophan accessibility to the quencher acrylamide, but higher tryptophan accessibility to the quencher iodide, while AMP caused higher tryptophan accessibility to acrylamide, and lower tryptophan accessibility to iodide. Also, the binding of nucleotides induces tryptophan heterogeneity in the protein. These findings lead us to propose that binding of nucleotides and adenine base cause different microenvironmental changes of the tryptophan residue, and Trp 192 may be involved in the active site of TCS.

No association of the 11778 mitochondrial DNA mutation and multiple sclerosis in Japan

Leber's hereditary optic neuropathy (LHON), a maternally inherited disease causing severe bilateral visual loss in young men, is linked to 12 point mutations in mitochondrial DNA, the most common of which is at the nucleotide position 11778. The 11778 point mutation has also been detected in several patients with possible multiple sclerosis (MS), especially women with severe visual loss in both eyes. Because frequent and severe optic neuropathy is a feature of MS in Japan, we screened 80 Japanese MS patients for the presence of the 11778 mutation by mutation-specific polymerase chain reaction. Eighteen women with MS had bilateral optic neuropathy, but none had the mutation at 11778. There is no association between Japanese MS and the 11778 mitochondrial DNA mutation.

Role of G proteins in the vasodilator response to endothelin isopeptides in vivo

The purpose of the present study was to determine the influence of pertussis toxin (PTX) on the pulmonary and systemic vasodilator responses to endothelin (ET) isopeptides in the intact cat under conditions of constant pulmonary blood flow and left atrial pressure. When pulmonary vasomotor tone was actively increased by an intralobar arterial infusion of U-46619, intralobar arterial bolus injections of ET-1, ET-2, and ET-3 decreased lobar arterial pressure and systemic vascular resistance in a dose-related manner. The vasodilator responses to ET-1 and ET-2 in the cat lung were abolished by PTX pretreatment, whereas PTX pretreatment did not alter the pulmonary vasodilator response to ET-3 and cromakalim, a specific ATP-sensitive potassium (KATP) channel activator, and the systemic vasodilator responses to all ET isopeptides studied. Glipizide, an inhibitor of KATP channels, inhibited the pulmonary vasodilator responses to ET-1, ET-2, and ET-3, whereas the systemic vasodilator responses to these isopeptides were not changed. The present data are the first to provide a functional correlate in vivo suggesting the existence of different signal transduction mechanisms for two pulmonary vascular ET receptor subtypes, ETA-like that is PTX sensitive and has greater sensitivity to ET-1 and ET-2 (than to ET-3) and ETc-like that is PTX insensitive and has sensitivity to ET-3 (than to ET-1 and ET-2). However, both ET-receptor subtypes promote vasodilation in the adult pulmonary vascular bed by activating KATP channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Reflection Intensities for the Components of Multiple Laue Diffraction Spots. III. Using a Real-Space Density Modification Method

In the Laue diffraction pattern, 10--20% of the spots result from the exact superposition of two or more reflections that are ;harmonics', e.g. hkl; 2h 2k 2l, ...; a high proportion of these are low-resolution reflections. For the solution of large or difficult structure problems, the intensities of the remaining 80-90% of the reflections, measurable as singles, may not be sufficient and thus the evaluation of the intensities of the components of the multiple spots is important. A new procedure, DECONV, for this deconvolution using real-space density modifications on the Patterson map is given. This development is based on a procedure in reciprocal space related to direct methods [Hao, Campbell, Harding & Helliwell (1993). Acta Cryst. A49, 528-531]. A Patterson map is calculated using single reflections and modified by removing negative densities and squaring with an appropriate adjustment at the origin peak. The procedure can be repeated until convergence is reached. It has been tested with Laue diffraction data from 4Zn insulin and cytochrome c peroxidase (CCP). 304 and 1134 reflection intensities were evaluated from multiple spots of insulin and CCP, respectively; the mean fractional differences (on F), showing the agreement with high-quality monochromatic data, were 0.27 and 0.21, respectively.

Influence of nifedipine, verapamil and diltiazem on pulmonary vascular resistance and vasoconstrictors in cats

In the present study, the effects of three classes of L-type calcium channel-blocking agents, nifedipine, verapamil and diltiazem, on the lobar arterial pressure and the vasoconstrictor responses in the pulmonary vascular bed were compared to those of cromakalim, a KATP channel activator, in the anaesthetized cat under controlled pulmonary blood flow and constant left atrial pressure. These drugs were infused intralobarly in doses selected which did not raise left atrial pressure, change cardiac output or alter systemic arterial pressure. Intralobar bolus injections of calcium channel-blocking agents and of the K+ channel activator decreased the lobar arterial pressure in a dose-related manner when pulmonary vasomotor tone was actively elevated by intralobar arterial infusion of U46619. The pulmonary vasodilator response to these agents was accompanied by a dose-related decrease of systemic arterial pressure. In decreasing lobar arterial pressure at elevated pulmonary vasomotor tone, the order of potency was nifedipine > verapamil > diltiazem, whereas in reducing systemic arterial pressure, the order of potency was nifedipine > diltiazem > verapamil. The calcium channel-blocking agents were less active than the reference drug, cromakalim, in both vascular beds. Intralobar arterial infusions of nifedipine, verapamil and diltiazem, at the rates of 0.03 mumol/min, 0.2 mumol/min and 0.1 mumol/min, respectively, caused no changes in cardiac output and in systemic and pulmonary arterial pressure. Infusion of all three calcium-channel-blocking agents blocked the pulmonary vasoconstrictor responses to BAY K 8644 (calcium entry promoter) and U46619 (thromboxane A2 mimic). Nifedipine infusion also reduced the pulmonary vasoconstrictor responses to methoxamine and BHT933 (alpha 1- and alpha 2-adrenoceptor agonists, respectively), whereas verapamil infusion reduced the responses only to methoxamine. Infusion of diltiazem caused no significant decrease of responses to either alpha-adrenoceptor agonist. The results of the present study suggest that the dihydropyridine, nifedipine, is more potent than the non-dihydropyridines, verapamil and diltiazem, in reducing the pulmonary vascular resistance and more effective in inhibiting the vasoconstrictor responses to the alpha-adrenoceptor agonists, to U46619 and to BAY K 8644 in the feline pulmonary circulation at the infusion rates which cause no or little hemodynamic changes.

Differential effects of pinacidil and cromakalim on vascular relaxation and sympathetic neurotransmission

We tested the hypothesis that pinacidil and cromakalim acted at different sites to relax vascular smooth muscle, in vitro. We compared the effects of pinacidil and cromakalim on tension development in isolated canine and bovine pulmonary artery and vein and canine mesenteric artery and dorsal metatarsal vein, and on the pre- and post-synaptic responses of the canine blood vessels to transmural nerve stimulation. Both pinacidil and cromakalim relaxed bovine and canine blood vessels precontracted to 50% of maximal tension with U46619, prostaglandin F2 alpha, or norepinephrine. Pinacidil- and cromaklim-mediated relaxations of the blood vessels were not mediated by endothelium-derived factors, prostanoids, muscarinic receptors, beta-adrenoceptors, or Ca(2+)-activated or voltage-dependent K+ channels, since they were unaffected by endothelium-rubbing, indomethacin, L-NG-monomethyl-L-arginine, atropine, propranolol, and charybdotoxin. Glibenchlamide, an inhibitor of ATP-activated K+ channels (K+ATP), and KCl (25-60 mM) sufficient to minimize the role of K+ channels almost abolished cromakalim- but not pinacidil-induced relaxation of the blood vessels. Pinacidil inhibited the contractions of the dorsal metatarsal vein and mesenteric artery to norepinephrine and transmural nerve stimulation and the efflux of 2-[14C]norepinephrine during transmural nerve stimulation. In contrast, 1 and 10 nM cromakalim enhanced while 0.1 and 1 microM cromakalim inhibited the contractions of, and 2-[14C]norepinephrine efflux from, the mesenteric artery and dorsal metatarsal vein during transmural nerve stimulation. Thus, pinacidil and cromakalim relax smooth muscle by stimulation of K+ATP channels. Pinacidil also relaxes the blood vessels by a K+ channel independent mechanism. Pinacidil-induced relaxation may also result from presynaptic inhibition of norepinephrine release from the sympathetic neuron.

Adrenomedullin dilates the pulmonary vascular bed in vivo

The present study was undertaken to investigate the effects of adrenomedullin (ADM), a newly discovered peptide in normal human plasma, in the pulmonary and systemic vascular bed of the intact cat. Because pulmonary blood flow and left atrial pressure were held constant, changes in lobar arterial pressure directly reflected changes in pulmonary vascular resistance. Under conditions of resting (low) pulmonary vasomotor tone, intralobar arterial bolus injections of ADM-(1-52) and two truncated ADM sequences, ADM-(13-52) and ADM-(1-12), had little effect on baseline lobar arterial pressure. In contrast, when pulmonary vasomotor tone was actively increased by intralobar arterial infusion of U-46619, intralobar arterial bolus injections of ADM-(1-52) (10-3,000 ng) and ADM-(13-52) (10-3,000 ng) decreased lobar arterial pressure in a dose-dependent manner, whereas only the highest doses of ADM-(1-52) and ADM-(13-52) (1,000-3,000 ng) mildly decreased systemic arterial pressure. Under the same experimental conditions, injections of ADM-(1-12) had no effect on lobar arterial and systemic arterial pressures. The present data suggest that ADM-(13-52) or a similar ADM fragment is responsible for the marked pulmonary vasodilator activity of ADM-(1-52) in vivo.

An adrenomedullin (ADM) fragment retains the systemic vasodilator activity of human ADM

The present study was undertaken to investigate the effects of human ADM, a newly discovered peptide present in normal human plasma, as well as a fragment of human ADM, human ADM13-52, on systemic hemodynamics in the anesthetized cat. Intravenous (i.v.) bolus injections of human ADM and human ADM13-52 decreased systemic arterial pressure (SAP) in a dose-dependent manner. Since neither peptide altered cardiac output, the decreases in SAP reflect reductions in systemic vascular resistance. The systemic vasodilator responses to the same doses of human ADM and human ADM13-52 in the cat were similar. The present study demonstrates the systemic vasodilator activity of ADM is conserved across species. The present data suggest that human ADM13-52 or a peptide structurally similar to it may mediate the hemodynamic properties of ADM in vivo in man. Since cardiac output and heart rate were not altered during the marked systemic vasodepressor response to ADM, activation of the ADM vasodilator mechanism may represent a therapeutic alternative in the clinical management of hypertensive diseases.

Failure to transfer multiple sclerosis into severe combined immunodeficiency mice by mononuclear cells from CSF of patients

To confirm the reported transfer of multiple sclerosis (MS) by CSF cells, we injected CSF cells from six MS patients in the exacerbation stage into the cisterna magna of 18 severe combined immunodeficiency mice. No clinical neurologic abnormalities or light- or electron-microscopic pathologic changes were present in any transferred mice, and the reported results could not be reproduced.

Tb(III) and Eu(III) as fluorescent probes to investigate the metal-binding sites of trichosanthin

Tb(III) and Eu(III) ions were used as fluorescent probes in the study of the trichosanthin (TCS). The fluorescence of Tb(III) was increased considerably when bound to TCS to replace the Ca(II) ions. The nonradiative energy transfer from fluorescent tryptophan (Trp) residues to the bound Tb(III) or Eu(III) took place. From a Foster d-d nonradiative energy transfer mechanism, it was obtained that the average distance between the bound Tb(III) and the Trp residue is 1.27nm. The results indicate that the major groups in TCS bound to Ca(II) ions should be the carboxylic side groups of the glutamic acid and/or aspartic acid. The fluorescent quenching of Ca(II)-free TCS by adding Tb(III) or Eu(III) into TCS from which the Ca(II) ions had been removed was discussed as well.

Evaluation of reflection intensities for the components of multiple Laue diffraction spots. II. Using the wavelength-normalization curve

In a Laue diffraction pattern, 10–20% of the spots result from the exact superposition of two or more reflections that are 'harmonics', e.g. hkl, 2h,2k,21 etc. The use of only the 80–90% of the reflections measurable as singles may not always be sufficient and evaluation of the intensities of the components of the multiple spots is therefore important. A procedure for this deconvolution is given, based on the varying nature of the wavelength-normalization curve. A feasibility trial has been carded out using a single Laue diffraction image of tetragonal hen egg white lysozyme (HEWL) recorded on an image plate. This allowed the intensities of 103 reflections to be evaluated from multiple spots. For these reflections, their agreement with monochromatic diffractometer data gave an R-factor of 0.157 for 96 common reflections. An earlier paper described another procedure based on direct methods, which addressed the same problem.