Adrenergic receptors coupled to adenylate cyclase in human cerebromicrovascular endothelium

Cultured endothelium derived from three microvascular fractions of human brain was used to characterize adrenergic receptors coupled to adenylate cyclase activity. Catecholamines (norepinephrine, epinephrine) and their analogs (isoproterenol, phenylephrine, 6-fluoronorepinephrine) dose-dependently stimulated endothelial production of cAMP. Antagonists for ß₁ and ß₂receptors (propranolol, atenolol, and butoxamine) and for 1-receptors (prazosin) dose-dependently blocked cAMP formation induced by the tested adrenergic agonists. Clonidine, an ga₂>₁-agonist, also inhibited isoproterenol-stimulated production of cAMP while yohimbine (₂>₁ antagonist) augmented the norepinephrine or epinephrine-induced accumulation of cAMP. Cholera toxin-induced ADP ribosylation of the stimulatory guanine nucleotide binding protein (G_s) abolished the stimulatory effect of norepinephrine, epinephrine, phenylephrine or 6-fluoronorepinephrine on cAMP formation. ADP ribosylation of the inhibitory guanine nucleotide binding protein (G_i) by pertussis toxin had no effect on either phenylephrine-or 6-fluoronorepinephrine-induced production of cAMP while it increased the norepinephrine and epinephrine-induced accumulation of cAMP. These findings represent the first documentation of ß₁-, ß₂-, ₁ and 2-adrenergic receptors linked to adenylate cyclase in endothelium derived from human brain microvasculature. These data also indicate that activation of endothelial ₁ -adrenergic receptors is mediated by a signal transduction mechanism associated with G_s protein. The results strongly support the presence of various receptor-controlled adrenergic regulatory mechanisms on human cerebromicrovascular endothelium.     

Ergonovine-induced constrictions of epicardial coronary arteries in conscious dogs: α-adrenoceptors are not involved

Summary The effect of i.v. ergonovine tartrate infusions (0.05–20 g/kg/min, 12 minutes duration) on coronary arteries was studied in 14 conscious dogs instrumented to continuously measure vascular diameter by an ultrasonic dimension gauge using 10-MHz piezoelectric crystals.Ergonovine induced a biphasic coronary response: small, transient dilation during the first minutes of infusion, followed by slowly developing constriction reaching its maximum 5 to 15 minutes after the end of the infusion and persisting at this level for at least 10 minutes. The threshold dosage for significant constriction was 0.05 g/kg/min. A dosage of 5 g/kg/min (cumulative 60 g/kg, corresponding to 35 g/kg ergonovine maleate) caused a decline in mean left circumflex artery diameter by 137±15 m (=4.6%) without significantly altering heart rate, plasma catecholamines or plasma renin activity. Coronary venous O₂ saturation did not decline, indicating the absence of coronary resistance vessel constriction. The epicardial artery constriction was not attenuated by a vasopressin antagonist. Under adrenergic blockade (2 mg/kg phentolamine and 2 mg/kg nadolol) or under ganglionic blockade (5 mg/kg pentolinium tartrate), ergonovine (5 g/kg/min) caused substantial elevation in mean arterial pressure, while the decline in coronary artery diameter was attenuated. When this increase in arterial pressure was prevented by appropriate bleeding, the ergonovine-induced coronary constriction was not diminished by adrenergic or ganglionic blockade. The serotonin antagonist methysergide (0.5 mg/kg) completely abolished the ergonovine-induced coronary artery vasomotion.It is concluded that ergonovine in dogs causes an epicardial coronary artery constriction comparable to the diffuse coronary artery narrowing in men not suffering from variant angina pectoris. These constrictions are not mediated by an adrenergic mechanism.Supported by Deutsche Forschungsgemeinschaft. Dedicated to Prof. Dr. A. Fleckenstein on the occasion of his 65th birthday.     

Regulation of the release of tumour necrosis factor (TNF)α and soluble TNF Receptor by γ irradiation and interferon γ in Ewing's sarcoma/peripheral primitive neuroectodermal tumour cells

This study analyses the production of tumour necrosis factor (TNF) and soluble TNF receptor (sTNF-R) before and after exposure to irradiation and interferon (IFN) in 12 cell lines derived from Ewing's sarcoma (ES)/peripheral primitive neuroectodermal tumours (pPNET). Supernatants from ES/pPNET cell cultures were tested in a TNF-specific amplified enzyme-linked immunosorbent assay (ELISA), a bioassay, and sTNF-R_p55 and sTNF-R_p75 ELISA. The tumour cell lines released minimal amounts of TNF, prominent amounts of sTNF-R_p55 (7/12 cell lines) and no sTNF-R_p75. Exposure to irradiation (5 Gy) either induced (3/12) cell lines) or up-regulated (3/12 cell lines) TNF release without changing sTNF-R_p55 and sTNF-R_p75 levels. Priming of cultures with recombinant human IFN (rhIFN) markedly enhanced TNF secretion in the radiation-responsive cell lines and had no influence on sTNF-R_p55 and sTNF-R_p75 levels. rhIFN affected the magnitude rather than the sensitivity of the radiation response. The TNF secreted was bioactive, as shown by its cytotoxic effect of WEHI-164 cells, and neutralization of its activity by anti-TNF monoclonal antibody. Herbimycin A (a tyrosine-specific protein kinase inhibitor) but not calphostin C (a protein kinase C inhibitor), H89 (a protein kinase A inhibitor), AACOCF3 (a specific inhibitor of phospholipase A₂) and MK-886 (a specific inhibitor of 5-lipoxygenase) abrogated -irradiation-stimulated TNF release. The antioxidantsN-acetylcysteine, nordihydroguaiaretic acid and mepacrine dose-dependently inhibited -irradiation-mediated TNF production. Collectively our findings indicate that IFN priming potentiates the secretion of bioactive TNF by ES/pPNET cells in response to irradiation without affecting sTNF-R release. The data suggest a requirement for protein tyrosine kinase activity and a role for reactive oxygen species in the -irradiation-mediated intracellular signalling pathway leading to TNF production.     

Demonstration of intrathecal and systemic morphine and ST-91 effects on fed canine upper gut motility

We studied the effects of opioid and adrenergic agonists and antagonists given systemically intravenously and intrathecally on postprandial antral and small bowel motility in a chronic conscious dog model. We studied eight dogs with a surgically implanted thoracic spinal intrathecal injection catheter, and six gastrointestinal manometric perfusion catheters. Morphine given intrathecally or intravenously induced propagated clusters of intestinal pressure activity in the fed dogs. The minimal effective dose for morphine was 150 g/kg by the intrathecal route and 450 g/kg by the intravenous route. ST-91 (an ₂-adrenergic agonist) profoundly inhibited antral and small intestinal pressure activity with similar minimal effective dose (100 g/kg) and duration of effect for both intravenous and intrathecal routes. Neither naloxone (3000 g/kg) nor combined phentolamine (1500 g/kg) with propranolol (300 g/kg) altered postprandial antral or small intestinal motility. The capacity of pharmacologic agents to block morphine-induced activity fronts when administered in the same compartment (intravenously or intrathecally) was investigated. The minimally effective morphine-antagonist dose for naloxone was similar intrathecally and intravenously (36 g/kg for both routes). ST-91 (100 g/kg) when given intrathecally or intravenously blocked morphine-induced clustered phasic pressure activity while simultaneously abolishing postprandial small intestine phasic pressure activity. These data suggest the presence of opioid and ₂-adrenergic receptors in the spinal cord that can modulate gastrointestinal motility in the postprandial state. Pharmacological interactions between these systems occur at spinal and target organ levels.     

Early and Late QRS Morphology and Width in Biventricular Pacing: Relationship to Lead Site and Electrical Remodeling

48 patients (40 Male), mean age 68 ± 8 years, in III–IV class, with intraventricular conduction delay, received a biventricular pacemaker. Heart failure aetiology was non-ischemic in 60%. Left ventricular lead positioning was inferior in 5 patients (10%), posterior in 12 (25%), lateral in 18 (37%) and anterior in 13 (27%). QRS duration and axis were evaluated in sinus rhythm, and during right ventricular pacing, left ventricular pacing and biventricular pacing, the last early after implant and late after 8.8 ± 4.3 months. QRS duration (ms) was 154 ± 29 in sinus rhythm, 175 ± 28 during right ventricular pacing, 196 ± 31 during left ventricular pacing, 122 ± 23 during biventricular pacing early and 120 ± 18 during biventricular pacing late. All the differences were statistically significant, but not between early and late biventricular pacing. Mean QRS axis (°) was –27 ± 32 in sinus rhythm, –75 ± 4 during right ventricular pacing, 112 ± 41 during left ventricular pacing, –82 ± 51 during biventricular pacing early and –80 ± 42 during biventricular pacing late. Only the difference between left ventricular pacing and all the other groups was statistically significant. QRS axis did not significantly differ according to left ventricular lead site during left and biventricular pacing. Late compared with early biventricular pacing axis showed variation >30° in 35% of patients, in spite of no significant changes in QRS duration and x-ray positioning. Conclusion: Biventricular pacing significantly reduced QRS width, which persisted long-term. Left and biventricular pacing axis was poorly related to left ventricular lead positioning. Biventricular pacing axis variability over time may suggest a role of electrical remodeling.     

Modulation of pacemaker activity in sheep cardiac Purkinje fibers by stimulation of β-adrenoceptor subtypes

The electrophysiological effects mediated by ₁- and ₂- in spontaneously active sheep cardiac Purkinje fibers were investigated using the non-selective agonist (–)-isoproterenol (IPN) and the selective agonists (–)-noradrenaline (₁) and procaterol (₂) in the absence and presence of the selective antagonists bisoprolol (₁) and ICI 118,551 (₂).IPN (0.01 mol/l) increased the spontaneous rate by 54% and the slope of diastolic depolarization by 68% of the respective control values. Further, IPN increased the action potential duration at –20 mV (APD –20 mV) from 96 to 154 ms, reduced the APD –70 mV by 17% and the duration of the diastole by 39% and slightly hyperpolarized the maximum diastolic potential. These effects were partially inhibited by ICI 118,551 (0.03 mol/l), diminished by bisoprolol (0.1 mol/l) and almost completely blocked by the combination of both antagonists. Concentration response curves of IPN were influenced by the selective antagonists as follows: ICI 118,551 (0.03 mol/l) shifted the curves to the right by 0.2–0.4 log units and increased the slope factor. Bisoprolol (0.1 mol/l) induced a greater shift to the right by 1.1–1.5 log units. Combination of bisoprolol with ICI 118,551 shifted the curves to the right by 1.5–1.7 log units.Noradrenaline (0.3 mol/l) elicited similar actions as IPN. Bisoprolol (0.1 mol/l) shifted the concentration response curves of noradrenaline to the right by 1.1–1.9 log units. Actions of procaterol (0.1 mol/l) were weak, attained only 15–35% of the maximal effects of IPN and could be blocked by ICI 118,551 (0.03 mol/l).These results show that the increase of pacemaker activity induced by catecholamines in sheep cardiac Purkinje fibers is predominantly mediated by stimulation of ₁. However, contribution of ₂ mediated effects could be demonstrated.Supported by Ministerium für Wissenschaft und Forschung, Nordrhein-Westfalen, Projekt-Nr, 40008786.     

Site of Bismuth Absorption from Bismuth Subsalicylate

Poorly absorbed bismuth preparations may benefit a variety of chronic colonic conditions including ulcerative colitis. Bismuth-induced neurotoxicity is a potential complication of the chronic use of these preparations, and a less-absorbable form of bismuth is needed. If bismuth absorption occurs primarily in the upper gut, a delayed-release bismuth preparation could reduce absorption. We studied the site of bismuth absorption from bismuth subsalicylate (BSS) in rats. For 15 days, BSS (50 mg/day) was ingested or infused directly into the cecum via a chronically implanted cannula. Oral BSS resulted in serum and urine bismuth levels many times higher (3.5 ± 0.3 g/liter and 1570 ± 286 g/g creatinine, respectively) than with cecal administration (undetectable (<1.5 g/liter) and 75 ± 25 g/g creatinine). Thus, bismuth absorption from BSS occurred almost entirely in the upper gut. These findings provide a rationale for a similar study of delayed-release bismuth preparations in humans.     

Additional value of thallium-201 SPECT to a conventional exercise test for the identification of severe coronary lesions after an episode of unstable coronary artery disease

The additional value of thallium-201 SPECT to a conventional exercise test for the identification of patients with severe coronary lesions was evaluated in 170 men, one month after an episode of unstable coronary artery disease. Severe coronary lesions at coronary angiography — defined as three vessel disease, left main stenosis or proximal left anterior descending artery stenosis as part of two vessel disease — were observed in 45.9%. In the SPECT image, the left ventricular myocardium was divided into nine segments and each segment was classified as either normal (=0), reduced uptake (=1) or uptake defect (=2). The sum of gradings in all segments post-exercise was denoted SPECT score. The patients were divided into nine different groups regarding ST-depression during exercise (no ST-depression, ST-depression in 1–2 leads or 3 leads) and SPECT score (no SPECT score, 1–3 scores or 4 scores). Severe coronary lesions were, in 68% identified by SPECT score 4 and in 65% by ST-depression in 1 lead at exercise test. The specificity for identification of severe coronary lesions was, for both tests, 65%. SPECT score 4 and/or ST-depression in 3 leads identified 82% of the patients with severe coronary lesions with a specificity of 63%. Furthermore, SPECT score 3 identified more patients with isolated proximal left anterior descending artery stenosis than ST-depression alone at exercise test.     

Effects of vasoactive stimuli on coronary vascular resistance in isolated perfused rabbit hearts: No vasospastic response to ergonovine with or without atherogenic diet

The mechanism of ergonovine-provoked coronary vasospasm is poorly understood. We tested the effect of ergonovine in perfused hearts from normal and cholesterol-fed (18 weeks, 2% cholesterol diet) rabbits in a constant-flow Langendorff perfusion. Aortic perfusion pressure was monitored to measure coronary vascular resistance, and left ventricular pressure was measured with an isovolumetric balloon in the left ventricle. Control coronary vascular resistance was 1.12±0.11 mm Hg/ml/min in hearts from normal rabbits and 1.53±0.16 mm Hg/ml/min in hearts from cholesterol-fed rabbits (n=9 each, , p<0.05). The cholesterol content of aortae from cholesterol-fed rabbits was markedly increased (432±85 mg/g protein vs. 14.9±8.2 in controls, p<0.001; for coronaries: 396±136 mg/g protein vs. 125±25, p<0.05). In both groups, increases in coronary vascular resistance were observed with vasopressin (40 IU/1) and phenylephrine (30 M) and decreases with adenosine (10 M), isoprenaline (0.1 M) and 30 sec stopflow (all p<0.05). Ergonovine maleate (10 M) and serotonine (10 M) did not increase coronary vascular resistance.Although in whole heart perfusion small changes in the caliber of epicardial vessels may not be detectable, changes severe enough to produce measurable changes in total coronary resistance were not found. Therefore the absence in our model of an increase in coronary vascular resistance after ergonovine is not compatible with a local direct mechanism in epicardial arterial wall, even when sensitized by a high cholesterol diet.Supported in part by the Deutsche Forschungsgemeinschaft (Ar 139/2)     

Contractile activity and prostacyclin generation in isolated coronary arteries from diabetic dogs

Summary The present study was aimed at determining the generation of prostacyclin (PGI₂)-like-material in coronary arteries from normal and diabetic (pancreatectomized) dogs as well as the contractile responses to prostacyclin of preparations from normal, diabetic and insulin-treated diabetic animals. PGI₂ produced a dose-dependent relaxation of coronary arteries from normal dogs. In contrast, those from diabetic animals were not relaxed; indeed, at low concentrations PGI₂ failed to evoke any effect but at higher ones it induced a distinct contraction. In arteries from diabetic animals treated with insulin, PGI₂ induced a biphasic contractile effect, which lay between that of normal controls and untreated diabetics. In addition the basal generation of PGI₂-like-material by coronary arteries was significantly higher in the diabetic (141±0.2 pg/mg, mean±SEM) than in normal dogs (59±0.2 pg/mg). The present experiments demonstrate that the generation of PGI₂-like-substance is significantly increased in coronary arteries from diabetic dogs, but the same vessels are unable to respond to added authentic PGI₂ with relaxation; on the contrary they react with a distinct positive contractile response.     

Insulino-sécrétion étudiée sur le pancréas isolé et perfusé du rat II. Action des catécholamines et des substances bloquant les récepteurs adrénergiques

Résumé Nos expériences réalisées sur le pancréas isolé et perfusé du rat, dont la sécrétion est légèrement stimulée par le glucose à la concentration de 1.5 g/l, nous ont permis de constater les faits suivants: — 1. La L-adrénaline et la L-noradrénaline à faibles concentrations (0.0055 M/l et 0.011 M/l) provoquent une diminution importante de la sécrétion d'insuline. La L-adrénaline a une action plus fortement inhibitrice que la L-noradrénaline. La L-isoprénaline, à la concentration de 0.05 M/l stimule d'abord 'insulino-sécrétion puis provoque une diminution progressive. — 2. L'inhibition provoquée par la L-adrénaline est supprimée partiellement ou totalement par la phénoxybenzamine suivant la concentration de bloquant alpha adrénergique utilisée (0.6 M/l ou 6 M/l); elle n'est pas modifiée par le propranolol (1 M/l). — Le propranolol (1 M/l) s'oppose à la première phase stimulante de I'isoprénaline; la phénoxybenzamine (6 M/l) paraÎt s'opposer à la deuxième phase inhibitrice. — 3. Les substances bloquant les récepteurs alpha ou bêta adrénergiques (phénoxybenzamine, propranolol) dont l'étude sur l'insulino-sécrétion a été réalisée à l'aide de concentrations croissantes peuvent manifester des effets très différents suivant la concentration utilisée et suivant la phase au cours de laquelle leur action est étudiée.

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Insulin secretion studied on isolated perfused rat pancreas. II. Effects of catécholamines and adrenergic blocking drugs

Summary Our experiments carried out on isolated perfused rat pancreas, the insulin secretion of which is slightly stimulated by glucose at a concentration of 1.5 g/l, led to the following findings: — 1. L-adrenaline and L-noradrenaline at low concentrations (0.0055 M/l and 0.011 M/l) provoke a marked decrease of insulin secretion. L-adrenaline has a stronger inhibitory effect than L-noradrenalin. At a concentration of 0.05 M/l, L-isoprenaline, first stimulates insulin secretion, then provokes a progressive decrease. — 2. The inhibition provoked by L-adrenaline is partially or totally suppressed by phenoxybenzamine depending on the concentration of the alpha adrenergic blocking drug used (0.6 M/l or 6 M/l); this inhibition is not modified by propranolol (1 M/l). — Propranolol (1 M/l) counteracts the first stimulation phase induced by isoprenaline; phenoxybenzamine (6 M/l) seems to counteract the second inhibitory phase. — 3. The effects of alpha and beta adrenergic blocking drugs (phenoxybenzamine and propranolol) have been studied on insulin secretion using increasing concentrations; these substances exert different effects depending on their concentration and the phase in which their action is studied.

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Untersuchungen der Insulinsekretion am isolierten perfundierten Rattenpankreas. II. Wirkung von Katecholaminen und adrenergen Receptorenblockern

Zusammenfassung Unsere Untersuchungen am isolierten, perfundierten Rattenpankreas, dessen Sekretion durch eine Glucoselösung von 150 mg% leicht stimuliert wurde, erlaubten uns, folgende Tatsachen festzustellen: — 1. Geringe Konzentrationen (0.0055 M/l und 0.011 M/l) von L-Adrenalin und L-Noradrenalin rufen eine erhebliche Verringerung der Insulinsekretion hervor. Diese Hemmwirkung ist bei L-Adrenalin stärker ausgeprägt als bei L-Noradrenalin. Bei einer Konzentration von 0.05 M/l stimuliert L-Isoprenalin zunächst die Insulinsekretion, bewirkt aber später eine fortschreitende Verringerung. — 2. Die durch 1-Adrenalin ausgelöste Hemmung läß sich teilweise oder vollständig durch Phenoxybenzamin aufheben und zwar je nach der verwandten Konzentration dieses Alpha-Receptorenblockers (0.6 M/l oder 6 M/l), sie wird durch 1 M/l Propanolol nicht modifiziert. — Das Propanolol (1 M/l) hemmt aber die erste Stimulationsphase des Isoprenalins; das Phenoxybenzamin (6 M/l) scheint der zweiten Hemmphase entgegen zu wirken. — 3. Die Hemmer der adrenergen - und -Receptoren (Phenoxybenzamin, Propanolol), deren Wirkung auf die Insulinsekretion wir bei steigenden Konzentrationen untersucht haben, können je nach angewandter Konzentration und je nachdem, während welcher Phase man ihren Effekt prüft, ganz verschiedene Wirkungen entfalten.

     

Analysis of lymphocyte subsets in patients with aplastic anemia before and during immunosuppressive therapy

Summary To define the contribution of T-lymphocyte subsets in the development of aplastic anemia (AA), T-cell subpopulations including T cells, T cells, and TCS1-positive T cells, were analyzed by cytophotometry in the peripheral blood (PB) and bone marrow (BM) of patients with AA before and after 6 weeks of therapy with anti-lymphocyte globulin (ALG), methylprednisolone, and cyclosporin A (CSA). In nine patients with AA a significant decrease of PB- and BM-derived T cells was observed after 6 weeks of therapy as compared with normal controls. At diagnosis, the CD4/CD8 ratio in PB and BM of the patients did not differ from the ratio in the control population; however, a reversed ratio (< 1) was present in PB as well as in BM after weeks of therapy. Interestingly, lymphocytes expressing the T-cell receptor (TCR) were significantly decreased both before (PB 1.2±0.1%; BM 0.8±0.1%) and after 6 weeks of therapy (PB 0.7±0.1%; BM 0.7±0.1%) as compared with healthy controls (PB 2.4±0.2%; BM 2.3±0.2%). However, the proportion of the -T-cell subpopulation expressing the TCS1 phenotype was markedly increased before (PB 42±3.5%; BM 31±3%) and especially after 42 days of therapy (PB 77±12%; BM 45±2%) as compared with that in normal subjects (PB 19±2%; BM 9.7±0.8%). At present, follow-up is under evaluation to correlate these findings with hematological response. The pathophysiological significance of the observed alterations within the T-cell subsets and especially the T-cell populations will require further functional analyses, in particular since TCS1-positive T cells exhibit autoimmunological capacity.Presented at the annual meeting of the German Society for Hematology and Oncology, 4–7 October 1992, Berlin     

Alterations in Adrenergic Receptor Signaling in Heart Failure

In the failing heart, several changes occur in cardiac adrenergic receptor-signal transduction pathways. The most striking of these changes occur in -ARs, and of the changes in -adrenergic receptors, 1-receptor down-regulation is the most prominent. Other changes include uncoupling of 2-adrenergic receptors and increased activity of the inhibitory G-protein, Gi. Most of these changes appear to be related to increased activity of the adrenergic nervous system, i.e. increased exposure to norepinephrine. Antagonists of the adrenergic nervous system improve left ventricular function and outcome in patients with heart failure. This fact supports the notion that activation of these neurohormonal systems exerts a net long-term detrimental effect on the natural history of chronic heart failure and that myocardial adrenergic desensitization phenomena are at least partially adaptive in the setting of left ventricular dysfunction.     

Effects of Piclamilast,a Selective Phosphodiesterase-4 Inhibitor,on Oxidative Burst of Sputum Cells From Mild Asthmatics and Stable COPD Patients

Oxidative stress associated with increased presence of neutrophils is an important feature of inflammatory airways diseases like asthma or chronic obstructive pulmonary disease. We studied the in vitro effect of piclamilast (RP73401), a selective phosphodiesterase (PDE)-4 inhibitor, compared to theophylline and prednisolone, on respiratory burst of sputum cells from mild asthmatics and COPD patients. Sputum cells were harvested from mild asthmatics and stable COPD patients and treated with piclamilast, theophylline or prednisolone. Respiratory burst was assessed by luminol-dependent chemoluminescence after stimulation with 10 M n-formyl-met-leu-phe (FMLP). Piclamilast inhibited FMLP-induced respiratory burst of sputum cells in a concentration-dependent manner (asthma: EC₅₀ approximately 100 nM, max. inhibition: 97.5±5% at 100 M; COPD: EC₅₀ approximately 1 M, max. inhibition: 70.6±4.5% at 100 M), whereas maximal inhibition observed with theophylline (asthma: max. inhib. 27±15%; COPD: 6±2%, both p < 0.05 vs. piclamilast) and prednisolone (asthma: 16±6%; COPD: 7.8±6.2%, both p < 0.05 vs. piclamilast) was weaker. Inhibition by piclamilast was largely reversed through pretreatment of cells with the adenylcyclase inhibitor SQ22536. We concluded that piclamilast, a selective PDE-4 inhibitor, attenuates the respiratory burst of sputum cells from mild asthmatics and COPD patients in vitro. These data underline the potential of PDE-4 inhibition as a novel therapeutic approach to inflammatory airway diseases like asthma or COPD.     

Effects of angiotensin and ergonovine on large and small coronary arteries in the intact dog

Summary Angiotensin (ATN) and ergonovine (ERG) are known to cause vasoconstriction of the coronary bed. However, ATN effects have been described mainly on the coronary resistance vessels, while ERG effects have been described on proximal conductance vessels. Recent studies have shown that proximal and distal coronary arteries are regulated independently. To examine both proximal and distal effects of ATN and ERG on the same heart, we studied 7 intact dogs, anesthetized with Innovar (Fentanyl 0.4 mg, Droperidol 20 mg, in 1 ml) and nitrous oxide, which were subjected to direct left anterior (LAD) coronary infusion of angiotensin (0.1, 0.5 and 5 g/min) and ergonovine (0.5, 5, and 25 g/min). Using a quantitative angiographic technique to measure artery dimensions and microspheres to measure flow, ERG infusion showed significant large artery constriction at all doses (maximum: 38.9±7.8% area reduction), and a significant decrease in LAD coronary artery flow, while endocardial/epicardial flow ratio remained unchanged. ATN produced a biphasic effect on the large coronary arteries. The lowest dose produced constriction (12.3±3.7% area reduction), which returned toward control value with the 0.5 g/min dose (6.0±1.0% area reduction), and the 5 g/min dose (1.5±9.5% area reduction), and no significant changes were observed in LAD flow with ATN infusion. Endocardial/epicardial ratio was unchanged, but aortic pressure was significantly increased during 0.5 and 5 g/min ATN infusion. Coronary resistance (pressure/flow) increased with both ERG and ATN. ERG and ATN produce large and small coronary artery constriction. The coronary response to ERG in dogs is similar to the human coronary response, even though previous data indicated a minimal constrictor response to ERG in canine coronary arteries.     

A Three-dimensional Analysis of Blood Vessels in Bronchioloalveolar Carcinoma

The three-dimensional architecture of blood vessels within lung adenocarcinomas has not been well studied. In 19 cases with bronchioloalveolar carcinoma with central fibrosis, we three-dimensionally examined blood vessel architecture in 150 m thick sections stained with elastin staining and anti-CD34 antibody. We examined four regions: normal alveoli and three regions within the tumor including an area adjacent to the normal alveoli (external area), an area in which tumor cells were replacing epithelial cells (replacement area), and a central fibrotic area (fibrotic area). Elastin staining showed that elastic fibers formed the framework of the alveoli, and the alveolar structure shrank more strongly to the center of the tumor due to folding of alveolar walls invaded by adenocarcinoma cells. We also measured three vessel parameters in these four regions. The vessel diameters were 4.08±1.10 m, 3.95±1.02 m, 5.04±1.56 m, and 6.11±2.23 m, the circumferences of those vessels seen as complete circles were 43.11±12.78 m, 43.71±12.87 m, 95.21±39.32 m, and 126.77±54.65 m; the lengths between vessel bifurcations were 13.28±3.08 m, 13.47±4.58 m, 24.91±9.66 m, and 41.82±28.08 m in the normal alveoli, and the external, replacement, and fibrotic areas, respectively. Blood vessel architecture changed such that the vessels became larger and coarser towards the center of the tumor. Our three-dimensional analysis suggests continuous remodeling of alveolar capillaries rather than angiogenesis within bronchioloalveolar carcinoma.     

Secretory component and lactoferrin in pure pancreatic juice in chronic pancreatitis

To evaluate pathophysiological roles of proteins in pancreatic secretion, immunoreactive lactoferrin (LF) and secretory component (SC) were measured in the first fraction of the pure pancreatic juice obtained endoscopically from 17 control, 21 suspected (SCP), 14 noncalcified (NCP), and 14 calcified chronic pancreatitis (CCP) subjects. The protein and amylase tended to decrease both in concentration and output from control to CCP. LF concentration was elevated in CCP (18.0±4.9/ml) when compared with controls (2.3±0.2g/ml), and LF output in NCP (12.3±3.8 g/min) was increased from controls (3.8±0.6 g/min). The combination of high LF concentration with low protein output was observed in 10/14 in CCP but 0/14 in NCP and can be a biochemical discriminator of CCP from NCP. SC concentrations were also elevated in NCP (8.5±2.0 g/ml) and CCP (5.6±1.6 g/ml) from controls (1.2±0.2 g/ml). SC outputs in SCP (9.8±3.1 g/min) and NCP (21.1±4.8 g/min) were increased from controls (1.7±0.3 g/min), but there was no further increase in CCP. Hypersecretion of LF and SC in chronic pancreatitis is different, especially in CCP, although the mechanisms for hypersecretion are unknown.This study was supported in part by a research grant for intractable pancreatic disease from the Ministry of Health and Welfare, Japan.     

α-Adrenergic responses of isolated canine coronary microvessels

Although -adrenergic activation is known to increase coronary microvascular resistance in vivo, the magnitude of its segmental microvascular consequences is not well understood. Quantification of these effects in vivo is hindered by escape mechanisms that minimize the influences of constrictors, and alterations in flow and pressure, which effect microvascular tone by shear stress-dependent and myogenic mechanisms, respectively. To eliminate these confounding influences, we have studied responses in vitro under conditions with these variables controlled. We evaluated the diameter changes of isolated canine coronary arterioles (110±12 m, n=35) and venules (98±7 m, n=9) in response to -adrenergic activation by norepinephrine (10^–10 to 10^–4 M) in the presence of -adrenergic blockade by alprenolol (10^–6 M). In contrast to the situation in vivo, -adrenergic activation did not constrict isolated coronary arterioles, but constricted isolated coronary venules in a dose-dependent manner over a range of 10^–10 to 10^–4 M (–27 ±3% maximum diameter change). Coronary arteriolar -adrenergic constriction was not promoted by 1) subthreshold or vasoactive doses of the vasoconstrictors KCl, angiotensin II, U46619, endothelin-1, neuropeptide Y or arginine vasopressin, 2) inhibition of the presynaptic uptake of norepinephrine by imipramine (10^–6 M), 3) inhibition of EDRF synthesis by N^g-monomethyl-L-arginine (10^–5 M) or 4) inhibition of prostaglandin synthesis by indomethacin (10^–5 M). Furthermore, -adrenergic activation did not modify microvascular dilatation by adenosine (10^–9 to 10^–4 M) or nitroglycerin (10^–9 to 10^–4 M), suggesting that -adrenergic constriction in vivo is not due to attenuation of cAMP or cGMP-dependent mechanisms of coronary dilatation. In contrast to the lack of constriction in coronary arterioles, canine skeletal muscle arterioles exhibited significant -adrenergic constriction (–80±4%), maximum diameter change). The coronary venular -adrenergic constriction was significantly inhibited by both the ₁-and ₂-adrenergic receptor antagonists, prazosin (10^–8 M) and rauwolscine (10^–7 M), indicating a mixed population of ₁-and ₂-adrenergic receptors. These results suggest that coronary arterioles, but not venules, lose -adrenergic responsiveness during isolation and cannulation, or that the primary coronary microvascular response to -adrenergic activation is venular constriction.     

Age-related Variations in the Neuroendocrine Control,More Than Impaired Receptor Sensitivity,Cause The Reduction in the GH-releasing Activity of GHRPs in Human Aging

The mechanisms underlying the reduction in the GH-releasing activity of GHRPs in aging are still unclear. Aim of our study was to verify in man whether age-related impairment of the neurohormonal control of GH secretion and/or receptor alterations are involved in the reduced GH response to GHRPs in aging. To this goal, in 16 normal elderly subjects (E, 66–81 yr) and 12 young controls (Y, 24–28 yr) we studied the effects of 1.0, 2.0 and 3.0 g/kg iv Hexarelin (HEX), a synthetic hexapeptide, or GHRH, as well as the interaction among HEX (2.0 g/kg), GHRH (2.0 g/kg) and arginine (ARG, 0.5 gr/kg) on GH secretion. In Y the GH response to increasing doses of HEX (1.0 vs. 2.0 vs. 3.0 g/kg; AUC0;v–120 ± SEM: 1728.4 ± 406.4 vs. 2265.9 ± 298.4 vs. 2934.3 ± 482.2 g//L/h, p < 0.05 for 1.0 vs. 2.0 g/kg) and GHRH (649.6 ± 111.4 vs. 792.2 ± 117.6 vs. 1402.6 ± 363.0 g/L/h) showed a progressive increase. Two g/kg HEX and 1 g/kg GHRH were the maximal effective doses. Similarly, in E the GH response to increasing doses of HEX (336.7 ± 50.0 vs. 742.8 ± 157.9 vs. 1205.1 ± 178.1 g/L/h, p < 0.05 for 1.0 vs. 2 g/kg, p < 0.001 for 1.0 vs. 3.0 g/kg and p < 0.03 for 2.0 vs. 3.0 g/kg) and GHRH (183.8 ± 27.3 vs. 260.9 ± 17.3 vs. 356.1 ± 46.3 g/L/h, p < 0.005 for 1.0 vs. 3.0 g/kg and p < 0.05 for 2.0 vs. 3.0 g/kg) showed a progressive increase. In E the GH response to 3 g/kg HEX or GHRH were clearly higher than those to 2 g/kg. However, at each dose the GH responses to HEX or GHRH in E were lower (p < 0.05) than those in Y. In Y the GH response to HEX + GHRH was synergistical (4259.2 ± 308.0 g/L/h, p < 0.05). ARG strikingly potentiated the GHRH-induced GH rise (2640.8 ± 273.6 g/L/h, p < 0.01) but not the HEX-induced one (2371.7 ± 387.2 g/L/h) as well as the synergistical effect of HEX and GHRH (4009.1 ± 360.8 g/L/h). In E the GH response to HEX and GHRH was still synergistical (1947.7 ± 306.0 g/L/h, p < 0.05) but these responses were lower than those in young (p < 0.01). On the other hand, in E ARG restored the GH response to GHRH (1858.9 ± 172.8 g/L/h, p < 0.01) and even those to HEX (2069.5 ± 528.7 g/L/h, p < 0.01) and HEX + GHRH (4406.0 ± 1079.2 g/L/h, p < 0.05). Our present results indicate that the impairment of GHRP and GHRH receptor activity may have a role in the reduction of the somatotrope responsiveness in aging. However, the age-related reduction in the GH-releasing activity of GHRPs seems mainly dependent on age-related variations in the neural control, i.e. concomitant GHRH hypoactivity and somatostatinergic hyperactivity.     

Elevated serum beta-2-microglobulin — A prognostic marker for development of AIDS among patients with persistent generalized lymphadenopathy

Summary For evaluation of its prognostic value, the level of serum -2-microglobulin was determined in early serum samples from 88 patients with persistent generalized lymphadenopathy in a prospective longitudinal study. Patients with serum -2-microglobulin >2.6 mg/l were found to have a significantly higher risk of developing AIDS earlier when compared to patients with a lower level (p<0.001).

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Erhöhte -2-Mikroglobulin-Serumspiegel — prognostischer Marker für den Übergang in AIDS bei Patienten mit persistierender, generalisierter Lymphadenopathie

Zusammenfassung In einer prospektiven longitudinalen Studie wurden in frühen Serumproben von 88 Patienten mit persistierender generalisierter Lymphadenopathie Messungen des -2-Mikroglobulin-Spiegels vorgenommen, um dessen Wert als prognostischer Faktor zu bestimmen. Das Risiko für den Übergang in AIDS erwies sich bei Patienten mit -2-Mikroglobulin-Spiegeln von >2,6 mg/l als signifikant höher als bei Patienten mit niedrigeren Spiegeln (p<0,001).