[Weaning from Mechanical Ventilation in Patients with SARS-CoV-2 Infection after Prolonged Mechanical Ventilation - First Experience]. / Entwöhnung von der Beatmung (Weaning) nach Langzeitbeatmung infolge SARS-CoV-2-Infektion.

AIM: With the emergence of a new virus and the associated pandemic, the ICU started to see a brand new kind of patient with severe ARD. As with any disease, sometimes the discontinuation of mechanical ventilation for any reason can be difficult. As a center specializing in weaning patients after prolonged mechanical ventilation, we wanted to compare our results with weaning patients who had prolonged mechanical ventilation for other reasons than those of patients who had prolonged mechanical ventilation due to SARS-CoV-2 infection. METHODS: We obtained our data from WeanNet register, the weaning register of the German Institute for Lung Research (ILF). In our analysis, we included only patient data from January until July 2020, which was recorded in our in-house study files. RESULTS: Our analysis included data on 28 patients; 11 were treated with prolonged mechanical ventilation due to SARS-CoV-2 pneumonia, 17 had no SARS-CoV-2 infection. 81.2 % of SARS-CoV-2 patients were successfully weaned from invasive ventilator therapy compared to 76.4 % of patients without SARS-CoV-2. Mortality in the SARS-CoV-2 group was 18.2 % compared to 11.8 % in the other group. Patients with SARS-CoV-2 infections were predominantly males with preexisting cardiovascular disease or a history of nicotine abuse. ARDS was the most common cause of respiratory failure which led to primary intubation. CONCLUSION: Even though we were only able to analyze a small number of patient histories due to the novelty of the disease, we were able to show that patients with prolonged mechanical ventilation after SARS-CoV-2 infection can be equally successfully weaned compared to patients with prolonged mechanical ventilation due to other diseases. Risk factors for prolonged mechanical ventilation after a severe case of SARS-CoV-2 infection seemed to be male gender, nicotine abuse and cardiovascular disease.

Evidence for Rigid Triaxial Deformation in

An extensive, model-independent analysis of the nature of triaxial deformation in ^{76}Ge, a candidate for neutrinoless double-beta (0νßß) decay, was carried out following multistep Coulomb excitation. Shape parameters deduced on the basis of a rotational-invariant sum-rule analysis provided considerable insight into the underlying collectivity of the ground-state and γ bands. Both sequences were determined to be characterized by the same ß and γ deformation parameter values. In addition, compelling evidence for low-spin, rigid triaxial deformation in ^{76}Ge was obtained for the first time from the analysis of the statistical fluctuations of the quadrupole asymmetry deduced from the measured E2 matrix elements. These newly determined shape parameters are important input and constraints for calculations aimed at providing, with suitable accuracy, the nuclear matrix elements relevant to 0νßß.

Direct Evidence for Octupole Deformation in

Despite the more than 1 order of magnitude difference between the measured dipole moments in ^{144}Ba and ^{146}Ba, the octupole correlations in ^{146}Ba are found to be as strong as those in ^{144}Ba with a similarly large value of B(E3;3^{-}→0^{+}) determined as 48(+21-29) W.u. The new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhanced octupole strength, as revealed by fully microscopic calculations.

Direct Evidence of Octupole Deformation in Neutron-Rich

The neutron-rich nucleus ^{144}Ba (t_{1/2}=11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV ^{144}Ba beam on a 1.0-mg/cm^{2} ^{208}Pb target. The measured value of the matrix element, ⟨3_{1}^{-}∥M(E3)∥0_{1}^{+}⟩=0.65(+17/-23) eb^{3/2}, corresponds to a reduced B(E3) transition probability of 48(+25/-34) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.

First Direct Measurement of (12)C((12)C,n)(23)Mg at Stellar Energies.

Neutrons produced by the carbon fusion reaction (12)C((12)C,n)(23)Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction (12)C((12)C,p)(23)Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that (12)C((12)C,n)(23)Mg is crucial to the production of Na and Al in pop-III pair instability supernovae. It also plays a nonnegligible role in the production of weak s-process elements, as well as in the production of the important galactic γ-ray emitter (60)Fe.

Influence of procalcitonin on decision to start antibiotic treatment in patients with a lower respiratory tract infection: insight from the observational multicentric ProREAL surveillance.

Procalcitonin (PCT)-guided antibiotic stewardship is a successful strategy to decrease antibiotic use. We assessed if clinical judgement affected compliance with a PCT-algorithm for antibiotic prescribing in a multicenter surveillance of patients with lower respiratory tract infections (LRTI). Initiation and duration of antibiotic therapy, adherence to a PCT algorithm and outcome were monitored in consecutive adults with LRTI who were enrolled in a prospective observational quality control. We correlated initial clinical judgment of the treating physician with algorithm compliance and assessed the influence of PCT on the final decision to initiate antibiotic therapy. PCT levels correlated with physicians' estimates of the likelihood of bacterial infection (p for trend <0.02). PCT influenced the post-test probability of antibiotic initiation with a greater effect in patients with non-pneumonia LRTI (e.g., for bronchitis: -23 % if PCT ≤ 0.25 µg/L and +31 % if PCT > 0.25 µg/L), in European centers (e.g., in France -22 % if PCT ≤ 0.25 µg/L and +13 % if PCT > 0.25 µg/L) and in centers, which had previous experience with the PCT-algorithm (-16 % if PCT ≤ 0.25 µg/L and +19 % if PCT > 0.25 µg/L). Algorithm non-compliance, i.e. antibiotic prescribing despite low PCT-levels, was independently predicted by the likelihood of a bacterial infection as judged by the treating physician. Compliance was significantly associated with identification of a bacterial etiology (p = 0.01). Compliance with PCT-guided antibiotic stewardship was affected by geographically and culturally-influenced subjective clinical judgment. Initiation of antibiotic therapy was altered by PCT levels. Differential compliance with antibiotic stewardship efforts contributes to geographical differences in antibiotic prescribing habits and potentially influences antibiotic resistance rates.

Discrimination of phosgene from cyanogen chloride in recovered chemical munitions using tagged neutron interrogation with high-resolution gamma-ray spectroscopy.

The associated particle (AP) technique has recently been used with a high-purity germanium γ-ray spectrometer to assess its capability to improve field identification of recovered chemical warfare (CW) materiel through prompt gamma-ray neutron activation analysis (PGNAA) measurements. A particularly challenging pair of CW agents commonly found in recovered munitions are phosgene (CG) and cyanogen chloride (CK), which have two of three elements in common, i.e. chlorine and carbon, but differ in the third being either oxygen or nitrogen. The detection of both latter elements is complicated by high oxygen concentration in the field environment which interferes with the small signal produced from the chemical agents. The matter is further complicated by the precautionary field practice of overpacking recovered munitions with vermiculite in larger steel multiple round containers (MRCs), which places additional oxygen-rich material in contact with the munition while further attenuating an already weak signal emitted from the munition center. This work reports quantitative results from realistic field measurements of CG and CK simulants in mock 4.2-inch (11 cm) mortar rounds overpacked with vermiculite in a large MRC. Results obtained with the AP technique are compared to those obtained with the traditional PGNAA approach for both overpacked- and bare-munition measurements. The AP technique is shown to provide a much more confident discrimination between the two chemicals, particularly for the more challenging field-relevant overpacked measurements, where a significant gain in sensitivity to all the key elements (chlorine, carbon, nitrogen and oxygen) is achieved.

[Statement of the Austrian Society of Pneumology (ASP)]. / Stellungnahme der Österreichischen Gesellschaft für Pneumologie (ÖGP): Management von Patienten mit SARS-CoV-2-Infektionen und von Patienten mit chronischen Lungenerkrankungen während der COVID-19-Pandemie (Stand 27.04.2020).

The COVID-19 pandemic is currently a challenge worldwide. In Austria, a crisis within the health care system has so far been avoided. The treatment of patients with community-acquired pneumonia (CAP), including SARS-CoV­2 infections, should continue to be based on evidence-based CAP guidelines during the pandemic. However, COVID-19-specific adjustments are useful. The treatment of patients with chronic lung diseases must be adapted during the pandemic, but must still be guaranteed.

[The Effect of Selective Dry Cow Treatment on the Udder Health in Swiss Dairy Farms]. / Die Auswirkung des selektiven Trockenstellens auf die Eutergesundheit in Schweizer Milchviehbetrieben.

INTRODUCTION: The aim of the present study was to determine the effects of selective dry cow treatment (SDCT) on udder health in Swiss dairy farms compared to a blanket dry cow treatment (BDCT). Cows with a somatic cell count (SCC) of less than 250'000 cells/ml and after BDCT in the previous dry period were selected. These animals received a SDCT in the subsequent dry period. Cows with less than 150,000 cells/ml or a negative California mastitis test (CMT) received either no treatment (group oB) or an internal teat sealant (group ZV) in all teats. Cows with more than 150,000 cells/ml or a positive CMT were treated with antibiotics and teat sealants (group ZV+AB). The SCC before and after the dry period were determined. In addition, the incidence of mastitis treatments in the dry period and the first 100 days of the following lactation as well as rates of new intramammary inflammations and healing thereof were determined. Data from 115 cows were available for evaluation. The SCC postpartum of all cows after SDCT did not differ from those after BDCT in the previous year. In the group oB the SCC was significantly higher than in the previous year. While the group ZV+AB showed a significant decrease of SCC during the dry period, the other two groups showed an increase (p < 0.0001). In the group oB, the proportion of mastitis treatments increased from 0% after BDCT to 28% after SDCT without any udder treatment (p < 0.05). Due to the increasing problem of antimicrobial resistance, SDCT is a valuable alternative to the BDCT. In the present study the antibiotic consumption could be reduced by 63%, while the udder health after SDCT did not deteriorate. If cows with low SCC are dried off without antibiotics the end of lactation, it is beneficial to protect the udder during the dry period with a teat sealant.

INTRODUCTION: Le but de la présente étude était de déterminer les effets du tarissement sélectif sur la santé de la mamelle dans des exploitations laitières suisses par rapport à un tarissement systématique avec antibiotiques de couverture. Des vaches dont le nombre de cellules somatiques (CCS) était inférieur à 250 000 cellules/ml et qui avaient été taries avec une protection antibiotique lors de la lactation précédente ont été sélectionnées. Ces animaux ont été taris de façon sélective à la lactation suivante. Les vaches avec moins de 150 000 cellules/ml ou un test de mammite de Californie (CMT) négatif n'ont reçu aucun traitement (groupe oB) ou un obturateur de trayon interne dans tous les trayons (groupe ZV). Les vaches avec plus de 150 000 cellules/ml ou une CMT positive ont été traitées avec des antibiotiques et des obturateurs de trayons (groupe ZV + AB). Les CCS avant et après la période de tarissement ont été déterminés. En outre, l'incidence de traitements de mammite pendant la période de tarissement et les 100 premiers jours de la lactation suivante, ainsi que les taux de nouvelles inflammations mammaires et de leur guérison ont été relevées. Les données de 115 vaches étaient disponibles pour évaluation. Le nombre de cellules post-partum de toutes les vaches après tarissement sélectif ne différait pas de celui après utilisation systématique de tarisseurs l'année précédente. Dans le groupe oB, le CCS était nettement plus élevé que l'année précédente. Alors que le groupe ZV + AB a montré une diminution significative de la SCC pendant la période sèche, les deux autres groupes ont présenté une augmentation (p.

Search for long-term radiation trends in the environs of Swiss nuclear power plants.

Annually since 1989, biannually since 1994 the sites of the Swiss nuclear facilities are surveyed flying the same survey lines by airborne gamma ray spectrometry. The equipment and the data processing software used for those surveys were built and developed at the Institute of Geophysics, ETH Zurich. For mapping the ground radiation around the nuclear facilities, a pixel representation and a modified spectrum dose index (SDI) method are used. In the search for long-term trends, the local dose rates are calculated first and in turn the net dose rates. So far, no change in the radiation levels was detected over the last 13 years outside of the fenced sites of the nuclear facilities and, especially, no artificial radioactivity was present that could not be explained by nuclear weapon tests or by the Chernobyl event.

Thrombotic stroke following snake bites by the "Fer-de-Lance"Bothrops lanceolatus in Martinique despite antivenom treatment: a report of three recent cases.

BACKGROUND: The severity of envenoming from Bothrops lanceolatus is determined by the development of cerebral, myocardial or pulmonary infarctions, and occasionnaly by serious local envenoming. Introduction of specific antivenom has resulted in a dramatic improvement in the prognosis of this envenoming. Against this background, we report 3 recent cases of patients bitten by B. lanceolatus who developed cerebral infarctions despite early administration of antivenom. METHODS: In 1991 a protocol was designed to apply the same evaluation and treatment to all envenomed patients. The clinical results have been continuously monitored. RESULTS: Between April 1993 and July 2003, 128 envenomed patients (age 6-83 (mean 45) years) were treated. No coagulopathy, thrombotic complication or death occurred in patients who were given early antivenom therapy--up to 6h following the bite--and 126 patients recovered. Between August 2003 and October 2004, 10 additional patients (18-66 (mean 46) years) were given antivenom at the time of admission at hospital. Of these, 3 developed cerebral infarctions within 24h. Effectiveness of antivenom was tested on mouse, and found to be lower than specified by the manufacturer. DISCUSSION: Our data shows that recently the antivenom may have lost some of its efficacy. Possible mechanisms include variability in venom composition or loss of activity of the antibodies produced more than 15 years ago. The question is whether we should attempt to produce improved antivenom. This could include activity against the venom of Bothrops caribbaeus from the neighbouring island of St Lucia, which shares a monophyletic group with B. lanceolatus and whose venom produces a similar thrombotic syndrome. CONCLUSION: Prevention of systemic vessels thrombosis remains the main therapeutic challenge of B. lanceolatus envenoming in Martinique.

Inhibition of protein phosphatases by okadaic acid and calyculin-A differentially modulates hormonal- and forskolin-stimulated formation of cyclic AMP in AtT-20 corticotrophs: effect of pituitary adenylate activating polypeptide and corticotropin-releasing factor.

The effect of phosphatase inhibitors okadaic acid and calyculin-A on cAMP formation and adrenocorticotropic hormone (ACTH) secretion in AtT-20 corticotrophs was investigated. Both okadaic acid and calyculin-A inhibited dose-dependently the accumulation of cAMP in cells stimulated with pituitary adenylate cyclase activating factor (PACAP) and corticotropin-relating hormone (CRF). While in the case of okadaic acid the half-maximum inhibiting concentration was similar for both peptides (IC50 = 4 x 10(-7) M), it appeared that calyculin-A was about one order of magnitude more efficient in inhibiting the effect of PACAP than that of CRF (IC50 = 3.8 x 10(-9) M vs 2.0 x 10(-8) M, respectively). Importantly, the inhibitors blocked the activation by cholera toxin (which acts on Gs-like proteins) of cAMP formation, but failed to alter the effect of forskolin (which bypasses the receptor-G protein complex and activates adenylyl cyclase directly). Treatment of cells with calyculin-A significantly dampened adenylyl cyclase activity in cell membrane fraction, though to a lesser extent than it blocked cAMP formation in the whole cell. Both okadaic acid and calyculin-A inhibited CRF- and PACAP-induced secretion of ACTH. Our data hint that in AtT-20 corticotrophs, inhibition of phosphatases by modulating the state of phosphorylation of the receptor-G proteins complexes for CRF and PACAP, regulates cAMP formation and ACTH secretion.

Specific receptors for vasopressin in the pituitary gland: evidence for down-regulation and desensitization to adrenocorticotropin-releasing factors.

Specificity of binding of 3H-labeled arginine vasopressin [( 3H]AVP), down-regulation of receptors, and desensitization were studied in anterior pituitary glands of both Wistar and Brattleboro rats. Studies using both crude membrane fractions and isolated cells of anterior pituitaries revealed the presence of a single population of binding sites with a Kd of approximately 1 nM. The receptor recognized the following peptides, with AVP = lysine vasopressin = vasotocin greater than oxytocin = 1-deamino-(8-D-AVP) greater than d-(CH2)5-Tyr-(Me)-Val4-AVP greater than 1-deaminopenicillamine-(Val4-D-Arg8)VP. Neither corticotropin-releasing factor (CRF) nor any of the neuropeptides tested, including AVP ring and tail fragments, competed for tracer binding. Increased extracellular vasopressin levels due to chronic injections or long term adrenalectomy decreased receptor density by 80%, while oxytocin was less effective than AVP. Comparing binding data in Brattleboro homozygotes and heterozygotes revealed that AVP levels within the physiological range could down-regulate pituitary receptors as well. This could not be caused by occupation of sites by endogeneous vasopressin, since injection of large doses of peptide decreased tracer binding by less than 10%. Loss of pituitary receptors reduced 1) enhancement by AVP of CRF-induced cAMP accumulation, 2) intrinsic CRF-like activity and 3) synergistic effect of AVP on ACTH secretion elicited by CRF. This study thus provides evidence for the presence of highly specific vasopressin receptors in the anterior pituitary, which may undergo homologous down-regulation and desensitization in terms of cAMP production and ACTH release.

Effects of cyclic AMP and analogues on neurogenic transmission in the rat tail artery.

1 The effects of two 8-substituted analogues of adenosine 3':5'-cyclic monophosphate (cyclic AMP) were compared with those of forskolin and isoprenaline on [3H]-noradrenaline release and vasoconstriction induced by electrical field stimulation (24 pulses at 0.4 Hz, 200 mA, 0.3 ms duration) in the rat tail artery, in the absence and in the presence of protein kinase inhibitors. 2 8-Bromo-adenosine 3':5'-cyclic monophosphate (8-bromo-cyclic AMP, 10-300 microM), 8-(4-chlorophenyl-thio)-adenosine 3':5' cyclic monophosphate (8-pCPT-cyclic AMP, 3-300 microM), forskolin (0.3-10 microM) and isoprenaline (1 nM-1 microM) all concentration-dependently enhanced stimulation-induced [3H]-noradrenaline release. The effect of cyclic AMP analogues was larger (2.5 fold at 300 microM) than those of cyclic AMP elevating drugs (1.6 fold at 10 microM for forskolin and 1.5 fold at 30 nM for isoprenaline). 3 At concentrations active at the prejunctional level, the four drugs had differential effects on stimulation-induced vasoconstriction, which was enhanced by the two cyclic AMP analogues, decreased by forskolin and not significantly altered by isoprenaline. 4 The [3H]-noradrenaline release-enhancing effects of 8-bromo-cyclic AMP, forskolin and isoprenaline were significantly decreased by the cyclic AMP-dependent protein kinase (PKA) inhibitor (N-[2-((3-(4-bromophenyl)-2-propenyl)-amino)-ethyl]-5- isoquinolinesulphonamide, di-hydrochloride) (H-89; 100 nM). By contrast they were unaffected by the cyclic GMP-dependent protein kinase (PKG) inhibitor, 8-bromo-guanosine 3':5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-bromo-cyclic GMPS; 10 microM). By contrast they were unaffected by the cyclic GMP-dependent protein kinase (PKG) inhibitor,8-bromo-guanosine 3':5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-bromo-cyclic GMPS; 10 MicroM).At the same concentrations the PKA inhibitor attenuated only the nerve-induced vasoconstrictor responses obtained in the presence of 8-bromo-cyclic AMP, whereas the PKG inhibitor did not modify that obtained in the presence of 8-bromo-cycic AMP or forskolin.5. Exposure to the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (1 MicroM) enhanced nerve-evoked [3H]-noradrenaline release, and this effect was decreased by the PKC inhibitor, 2-[1-(3-dimethylaminopropyl)-indol-3-yl]-3-(-indol-3-yl)-maleimide (GF 109203X; 100 nM). However, the latter drug did not modify the enhancing effect of 8-bromo-cyclic AMP on [3H]-noradrenaline release.6. It is concluded that activation of cyclic AMP-dependent protein kinase is involved in the enhancing effect of cyclic AMP-elevating compounds on prejunctional release of noradrenaline. In addition the results provide no clear-cut evidence for a vasodilator role of PKA.

Effects of cyclic GMP and analogues on neurogenic transmission in the rat tail artery.

1. The effects of membrane permeable analogues of guanosine 3':5'-cyclic monophosphate (cyclic GMP), and of the NO donor, 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1) were investigated on [3H]-noradrenaline release and neurogenic vasoconstriction in electrical field stimulated rat tail arteries. 2. Two 8-substituted analogues of cyclic GMP (8-bromoguanosine 3':5'-cyclic monophosphate; 8-bromo-cyclic GMP and 8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphate; 8-pCPT-cyclic GMP) concentration-dependently enhanced stimulation-induced [3H]-noradrenaline release. These prejunctional effects were antagonized by the cyclic AMP-dependent protein kinase (PKA) inhibitor N-[2-((3-(4-bromophenyl)-2-propenyl)-amino)-ethyl]-5 isoquinolinesulphonamide dihydrochloride (H-89; 100 nM) but not by the cyclic GMP-dependent protein kinase (PKG) inhibitors, Rp-8-bromoguanosine 3':5'-cyclic monophosphorothioate (Rp-8-bromo-cyclic GMPS; 10 microM) or Rp-8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphorothioate (Rp-8-pCPT-cyclic GMPS; 10 microM). 3. beta-Phenyl-1,N2-ethenoguanosine 3':5'-cyclic monophosphate (PET-cyclic GMP) had no effect on stimulation-induced [3H]-noradrenaline release but concentration-dependently decreased the stimulation-induced vasoconstriction. 4. The two 8-substituted cyclic GMP derivatives, PET-cyclic GMP and SIN-1, both decreased stimulation-induced vasoconstriction. In addition, SIN-1 relaxed rat tail arteries precontracted with phenylephrine (1 microM). The SIN-1 concentration-relaxation curve was shifted in parallel manner to the right by Rp-8-bromo-cyclic GMPS (10 microM) and Rp-8-pCPT-cyclic GMPS (10 microM) with no change in the maximum effect, showing that the relaxation was mediated by a cyclic GMP/PKG-dependent mechanism. 5. It is concluded that PKA activation is involved in the noradrenaline release enhancing effect of the two 8-substituted cyclic GMP analogues, whereas a cyclic GMP/PKG-operated pathway accounts for the inhibitory effects of the cyclic GMP and its analogues on vascular smooth muscle contraction.

Role of the L-arginine-NO pathway and of cyclic GMP in electrical field-induced noradrenaline release and vasoconstriction in the rat tail artery.

1. The possible roles of the L-arginine-NO pathway and of guanosine 3':5'-cyclic monophosphate (cyclic GMP) in regulating the prejunctional release of noradrenaline and neurogenic vasoconstriction were investigated in the perfused rat tail artery. 2. In the presence of N omega-nitro-L-arginine methyl ester (L-NAME; 30 microM), an inhibitor of NO formation, the vasoconstrictor responses to perivascular nerve stimulation (24 pulses at 0.4 Hz, 0.3 ms, 200 mA) and to exogenous noradrenaline (1 microM) were significantly enhanced, whereas the stimulation-evoked tritium overflow from [3H]-noradrenaline preloaded arteries was not modified. The vasoconstriction enhancing effect of L-NAME was prevented by L-arginine (1 mM) but not D-arginine (1 mM) and was abolished by removal of the endothelium. 3. The NO donor, 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1; 0.1-30 microM), and the cyclic GMP phosphodiesterase inhibitor, zaprinast (0.1-30 microM) both induced a concentration-dependent inhibition of the electrical field stimulation-induced vasoconstriction, while atrial natriuretic peptide (ANP; 100 nM) produced only a slight decrease of the vasoconstrictor response. Methylene blue (3 microM), a known inhibitor of soluble guanylate cyclase increased the electrical field stimulation-induced vasoconstriction. SIN-1 and methylene blue when administered simultaneously, antagonized each others effect. None of the compounds tested (SIN-1, zaprinast, ANP or methylene blue) had any significant effect on the stimulation-evoked [3H]-noradrenaline overflow. 4. 8-Bromo-cyclic GMP, a potent activator of cyclic GMP-dependent protein kinase, markedly and concentration-dependently (3-300 microM) increased [3H]-noradrenaline overflow but decreased field stimulation-induced vasoconstriction. Dibutyryl-cyclic GMP (100 JM), a weak activator of cyclic GMP-dependent protein kinase, affected neither the pre- nor the postjunctional response to electrical field stimulation.5. These data show that an NO-like substance of endothelial origin, derived from L-arginine, attenuates vasoconstriction in the rat tail artery, whether neurally-induced or evoked by exogenous noradrenaline.Since noradrenaline release was unaltered by compounds modifying NO production, this NO-like compound acted through a postjunctional mechanism. The lack of prejunctional effects of both soluble and membrane-associated guanylate cyclase activators, despite a large effect of 8-bromo-cyclic GMP,suggests that endogenous cyclic GMP production, if present in sympathetic nerves, may not be involved in the regulation of noradrenaline release in the rat tail artery.

Discrimination between neuropeptide Y and peptide YY in the rat tail artery by the neuropeptide Y1-selective antagonist, BIBP 3226.

1. The ability of the novel, nonpeptide, neuropeptide Y (NPY) Y1-selective antagonist, BIBP 3226 ¿(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-D-arginine amide¿, to antagonize the increase in perfusion pressure induced by NPY and peptide Y (PYY) was tested in the perfused rat tail artery, a postjunctional Y1-receptor bioassay, precontracted by 1 microM phenylephrine. 2. NPY and PYY produced a concentration-dependent enhancement of the vasoconstrictor response evoked by 1 microM phenylephrine. Although NPY and PYY are roughly equipotent, the maximal contractile response elicited by PYY was about twice that elicited by NPY. 3. Increasing concentrations of BIBP 3226 caused a parallel and rightward shift in the NPY concentration-response curve without depressing the maximal response. The contractile effect of NPY was potently inhibited in a competitive manner. The pA2 value for BIBP 3226 was 7.01 +/- 0.08, a value equivalent to that observed in the rabbit saphenous vein. Although increasing concentrations of BIBP 3226 shifted the concentration-response curve of PYY to the right without any significant decrease in the maximal vasoconstrictor response, the antagonism appeared non-competitive as the slope of the Schild plot was significantly different from unity (0.58 +/- 0.04). 4. In conclusion, these data confirm that BIBP 3226 is a potent and selective nonpeptide Y1 receptor antagonist. Moreover, they show that complex interactions occur between BIBP 3226 and postjunctional receptors activated by PYY. We postulate that BIBP 3226 might discriminate between the effects of NPY and PYY at the postjunctional level in the rat tail artery. It may be that distinct receptors for NPY and PYY exist; these may or may not allosterically interact with each other. Another working hypothesis would be that there is a single receptor complex with allosterically interacting binding sites for the two peptides.

Vasoconstrictor effects of various neuropeptide Y analogues on the rat tail artery in the presence of phenylephrine.

1. The increase in perfusion pressure induced by neuropeptide Y (NPY), peptide YY (PYY) and related peptides were compared in the perfused rat tail artery precontracted by a submaximal concentration (1 microM) of the vasoconstrictor, phenylephrine. 2. NPY, PYY, [Leu31,Pro34]NPY, [Glu16,Ser18,Ala22,Leu28,31]NPY (ESALL-NPY) and the centrally truncated and stabilized analogues [D-Cys5,8-aminooctanoic acid7-20, Cys24]-NPY (D-Cys5-NPY) and [D-Cys7, 8-aminooctanoic acid8-17,Cys20]-NPY (D-Cys7-NPY) produced a concentration-dependent enhancement of the vasoconstrictor response induced by 1 microM phenylephrine. PYY was two times more potent than NPY and [Leu31,Pro34]NPY while ESALL-NPY, D-Cys7-NPY and D-Cys5-NPY were approximately 3, 5 and 16 times less potent than NPY respectively. NPY, D-Cys5-NPY and D-Cys7-NPY gave similar maximal responses whereas those observed for PYY, [Leu31,Pro34]NPY and ESALL-NPY were much greater than that of NPY. 3. NPY 13-36 and [des-Ser3,Lys4,Cys2,8-aminooctanoic acid3-24, D-Cys27]-NPY ([es-Ser3,Lys4]Cys2-NPY) were practically inactive at concentrations up to 3 microM, whereas [des-Ser3,Lys4,D-Cys2,8-aminooctanoic acid3-24,Cys27]-NPY ([des-Ser3,Lys4]D-Cys2-NPY), which differs from [des-Ser3,Lys4]Cys2-NPY in the disulphide bridge (a D-Cys in position 2 for [des-Ser3,Lys4]D-Cys2-NPY instead of an L-CYs for [des-Ser3,Lys4]Cys2-NPY) was a weak agonist the maximal effect of which could not be ascertained. 4. The contractile effects of [des-Ser3,Lys4]D-Cys2-NPY were additive with those of NPY and [Leu31,Pro34]NPY demonstrating that it is not a partial agonist but may simply not interact competitively with the receptor binding site for NPY. NPY and PYY interacted in a manner expected of agonists competing for the same binding site.5. PYY, NPY and [Leu31,Pro34]NPY were equipotent in displacing the I125-labelled PYY from binding sites on membranes from Y1-receptor expressing SK-N-MC cells, while the centrally truncated analogues were much less potent. The rank order of potencies for displacement of the I125-PYY binding by these peptides in SK-N-MC cells correlated with their activity in enhancing the vasoconstrictor response of phenylephrine in the tail artery. For the [des-Ser3,Lys4]D-Cys2-NPY analogue, the displacement pattern was more complex in that the displacement analysis revealed the presence of two binding sites.6. In conclusion, these data provide no evidence for other than postjunctional Y1-receptors mediating the enhancement of the contractile response elicited by phenylephrine in the perfused rat tail artery. The effects of [des-Ser3,Lys4]D-Cys2-NPY indicate that the Y1-receptor may possess an allosteric binding site.

Inhibition of cyclic GMP-dependent protein kinase-mediated effects by (Rp)-8-bromo-PET-cyclic GMPS.

1. The modulation of the guanosine 3':5'-cyclic monophosphate (cyclic GMP)- and adenosine 3':5'-cyclic monophosphate (cyclic AMP)-dependent protein kinase activities by the diastereomers of 8-bromo-beta phenyl-1, N2-ethenoguanosine 3':5'-cyclic monophosphorothioate, ((Rp)- and (Sp)-8-bromo-PET-cyclic GMPS) was investigated by use of purified protein kinases. In addition, the effects of (Rp)-8-bromo-PET-cyclic GMPS on protein phosphorylation in intact human platelets and on [3H]-noradrenaline release and neurogenic vasoconstriction in electrical field stimulated rat tail arteries were also studied. 2. Kinetic analysis with purified cyclic GMP-dependent protein kinase (PKG) type I alpha and I beta, which are expressed in the rat tail artery, revealed that (Rp)-8-bromo-PET-cyclic GMPS is a competitive inhibitor with an apparent Ki of 0.03 microM. The activation of purified cyclic AMP-dependent protein kinase (PKA) type II was antagonized with an apparent Ki of 10 microM. 3. In human platelets, (Rp)-8-bromo-PET-cyclic GMPS (0.1 mM) antagonized the activation of the PKG by the selective activator 8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphate (8-pCPT-cyclic GMP; 0.2 mM) without affecting the activation of PKA by (Sp)-5, 6-dichloro-1-beta-D-ribofurano-sylbenzimidazole- 3':5'-cyclic monophosphorothioate ((Sp)-5,6-DCl-cyclic BiMPS; 0.1 mM). 4. (Rp)-8-bromo-PET-cyclic GMPS was not hydrolysed by the cyclic GMP specific phosphodiesterase (PDE) type V from bovine aorta but potently inhibited this PDE. 5. The corresponding sulphur free cyclic nucleotide of the two studied phosphorothioate derivatives, 8-bromo-beta-phenyl-1, N2-ethenoguanosine-3':5'-cyclic monophosphate (8-bromo-PET-cyclic GMP), had no effect on electrically-induced [3H]-noradrenaline release but concentration-dependently decreased the stimulation-induced vasoconstriction. (Rp)-8-bromo-PET-cyclic GMPS (3 microM) shifted the vasoconstriction response to the right without affecting stimulation evoked tritium overflow. 6. The NO donor, 3-morpholinosydnonimine (SIN-1) relaxed rat tail arteries precontracted with phenylephrine (1 microM). The SIN-1 concentration-relaxation curve was shifted in a parallel manner to the right by (Rp)-8-bromo-PET-cyclic GMPS, suggesting that the relaxation was mediated by a cyclic GMP/PKG-dependent mechanism. 7. The [3H]-noradrenaline release-enhancing effect and stimulation-induced decrease in vasoconstriction of forskolin were unaffected by (Rp)-8-bromo-PET-cyclic GMPS. Moreover, the forskolin concentration-relaxation curve was not changed in the presence of the PKG inhibitor, suggesting a high selectivity in intact cells for PKG- over PKA-mediated effects. 8. The results obtained indicate that (Rp)-8-bromo-PET-cyclic GMPS presently is the most potent and selective inhibitor of PKG and is helpful in distinguishing between cyclic GMP and cyclic AMP messenger pathways activation. Therefore, this phosphorothioate stereomer may be a useful tool for studying the role of cyclic GMP in vitro.