Finding Adequate Information: A Major Challenge for Policy-Makers in the Field of Cancer

Background and context: A global cancer epidemic is developing (GLOBOCAN 2012). In the case of low- and-middle-income countries, difficulties are cumulative: inadequate health systems, lack of training for professionals. Drastic decisions have to be taken in a very complex field. Good decision needs good information. What about information dedicated to policy-makers: to decide a question, they need specific information, marked by these features: synthetic, clear, scientifically validated. Actually, this is not easy to find. Moreover policy-makers can't really benefit from: 1. Information for health professionals which is complex and overabundant (the request “cancer” on PubMed “out” nearly 1.5 millions references). 2. Documents or testimonials for patients. Written by scientific societies or patients' associations, they mostly focus on 2 topics “understand your disease” and “how to cope with”. 3. Information from the Web, not always reliable in terms of quality. Strategy/Tactics: While policy advisors and international organizations provide appropriate studies and reports, mostly focused on “what should be done”, we believe that knowledge of basic cancer data are necessary to understand the proposals. We talk about issues like “what is cancer”, “what exactly cover radiotherapy, oncological surgery…”. Regarding French speaking Africa, Alliance Ligues Africaines and Méditérranéennes (ALIAM) and The French League have produced targeted information for decision-makers. The document was presented in Brazzaville in June 2017. Access to this book is free: www.livre-cancer.aliam.org . The editorial method was discussed and we made the choice to write short sheets, to quickly understand the useful definitions and problems. Rather than comprehensiveness, a pedagogical will and a desire for clarity guided the writing. Diagrams and photos had to be abundant to facilitate understanding. Moreover, this format allows a permanent update of the subjects and the introduction of new topics as needed. What was learned: On the basis of this experience, ALIAM and the league are convinced that a pedagogic document with an international vocation would be useful for all policy makers. Proposal for action: UICC would be the perfect organizer of a working group to produce such a document. The goal would be to develop a consensus text which resume essential data on all common themes of cancer. About 25 themes could be identified, e.g., definition and mechanisms of development of cancers, risk factors, screening and early diagnosis, anatomic pathology and telepathology, molecular biology, imaging and interventional radiology, surgery, radiotherapy, chemotherapy and innovative therapies, palliative care etc. Moreover, focus on specific location of cancer (breast, cervix, lung…) and pediatric cancers should be developed. Then, it would be easier for any world regions to supplement this validated information with additional specific data describing the local situation. Hierarchizing action priorities would be facilitated.

Diagnostic and prognostic value of endothelin-1 plasma concentrations in dogs with heart and respiratory disorders

The endothelin-1 (ET-1) plasma concentration was measured in dogs with spontaneous cardiac or respiratory diseases. Plasma samples were obtained from 76 healthy control dogs and 73 dogs, of which 58 were suffering from heart disease and 15 were suffering from respiratory disease. Dogs were evaluated using echocardiography, thoracic radiography, biochemical evaluation and a radioimmunoassay for ET-1. ET-1 plasma concentrations were significantly higher in dogs with spontaneous cardiac or respiratory diseases (mean [se] 5.3 [0.3] and 5.3 [0.6] pg/ml, respectively) than in healthy dogs (1.9 [0.1] pg/ml) (P<0.0001). ET-1 plasma concentrations increased with the class of heart failure (International Small Animal Cardiac Health Council classification) (P<0.0001) and with the severity of pulmonary disorders. ET-1 plasma concentrations were positively correlated with the extent of systolic pulmonary hypertension measured by Doppler echocardiography (P<0.05; r=0.75) and with the clinical outcome of dogs with respiratory disease. Evaluation of the ET-1 plasma concentration allowed differentiation between heart and respiratory disorders in dogs exhibiting clinical signs at exercise, but not in patients exhibiting clinical signs at rest.

Relationship between calcineurin inhibition and plasma endothelin concentrations in cyclosporine-A-treated kidney transplant patients

OBJECTIVE

The inter-individual variability of cyclosporine (CsA) pharmacokinetics is well known. However, there is obviously also an inter-individual pharmacodynamic variability, which might be explored by the measurement of biomarkers of CsA effects.

METHODS

In 11 renal transplant patients, blood CsA concentrations, calcineurin inhibition in peripheral blood mononuclear cells and endothelin plasma concentrations were measured over a 4-h period after CsA intake.

RESULTS

Mean plasma endothelin concentrations were higher than those of healthy subjects (3.66+/-0.46 pg ml(-1) versus 3.15+/-0.40 pg ml(-1), P<0.01) but were not related to CsA dose or blood concentrations. There was a linear relationship between calcineurin inhibition at t (0) and mean endothelin concentrations (r (2)=0.51, P<0.05). Patients with gingival hypertrophy had higher mean endothelin concentrations than patients without this complication (4.0 pg ml(-1) versus 3.4 pg ml(-1), P<0.01), although CsA doses and concentrations were not different between these two groups.

CONCLUSION

We observed a correlation between calcineurin inhibition and endothelin concentrations. Endothelin plasma concentrations is a biomarker of CsA effect, which may provide more information than CsA blood concentrations.

Renal and hormonal responses to isotonic saline infusion after 3 days' head-down tilt vs. supine and seated positions

AIM

The study aimed to determine whether prolonged exposure to simulated microgravity produces a level of thoracic volume receptor loading similar to that seen in the upright position or immediately after lying down.

METHODS

We used a cross-over design to compare responses to a saline infusion in eight healthy subjects during a 4-day, -6 degree head-down tilt (HDT) and in the acute seated and acute supine positions.

RESULTS

The first 24 h of HDT were associated with greater urinary excretion of water and sodium (UV, UNaV) than seated and acute supine [cumulative UV, 3035 +/- 219, 2311 +/- 156 (P < 0.05), and 2448 +/- 182 mL (P < 0.05), respectively; cumulative UNaV, 256 +/- 19, 180 +/- 11 (P < 0.05), and 189 +/- 15 mmol (P < 0.05), respectively]. Haemoglobin and haematocrit were increased after 24 h and plasma volume decreased after 48 h of HDT (P < 0.05). With prolongation of HDT, UV and UNaV returned near the baseline values, and plasma atrial natriuretic factor (ANF) and renin values returned to acute seated levels; in acute supine, ANF values were higher and renin lower than in the two other positions. After a 30-min infusion of 20 mL kg(-1) isotonic saline on the fourth HDT day or during acute seated or acute supine, sodium excretion within 4 h was similar during HDT and acute seated (83 +/- 6 and 84 +/- 9 mmol, respectively) and greater during supine (104 +/- 8 mmol, P < 0.05). The renin decrease was greater in HDT and seated than in supine. The plasma ANF increase was greater during HDT than during supine; during seated, plasma ANF was unchanged.

CONCLUSION

These data suggest that, after 4 days of HDT, thoracic volume receptor loading returns to the same level as in the seated position, leading to blunted responses to volume expansion as compared with the acute supine position.

Bradykinin-induced neuropeptide Y release by human pheochromocytoma tissue

Neuropeptide Y (NPY) and noradrenaline (NA) are frequently co-localized and co-released in the sympathetic nervous system. Since bradykinin (BK) is known to stimulate neurotransmitter release as NA in adrenal glands, we therefore hypothesized that BK might also be involved in the release of NPY. The effect of BK(1-9) on immunoreactive NPY (Ir-NPY) release was investigated in superfused human pheochromocytoma tissue. BK(1-9) (10(-7)-10(-5) M) was shown to induce a rapid Ir-NPY release in a concentration-dependent manner. This effect of BK(1-9) (10(-6) M) was mimicked by the B2 agonist [Phe(8)(CH(2)NH)Arg(9)]-bradykinin (10(-5) M) and blocked by the selective B2-receptor antagonist HOE140 (10(-5) M). Increasing Ir-NPY release was probably not mediated by nitric oxide (NO) since the outflow of Ir-NPY was not influenced by the NO synthase inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME) (10(-4) M). In presence of bapta-AM (10(-5) M), a chelator of cytosolic calcium, W7 (10(-5) M), a calmodulin inhibitor, TMB-8 (10(-5) M), a blocker of intracellular calcium mobilization and ryanodine (10(-5) M), a selective inhibitor of the Ca(2+)-induced release mechanism, the NPY release by BK(1-9) was significantly inhibited by 126%, 98%, 91%, and 94%, respectively. These results indicate that BK increased the release of NPY by the tumor acting through the interaction with the BK-B2 receptor and request intracellular calcium mobilization independently of a NO mechanism.

[Names-Lab : a model for the standardization of biology message exchanges]

The growing requirements of communication between health partners urges to standardize the language used in laboratories data management systems. Names-Lab is the only semantic reference system allowing to describe synchronously the body of prescription and result messages. Its hierarchical structure allows a simple coding, easily accessible to all biologists without imposing or even requiring a language. Other internationally proposed systems as Loinc and Euclides are similar to Names-Lab in their purposes but are completely different by their content and structure. This prompts the medical and biologic community for a comparison of these tools before setting the choice of an international referencing system.

Role of nitric oxide on atrial natriuretic peptide release induced by angiotensin II in superfused rat atrial tissue

The present study investigated the role of nitric oxide (NO) on atrial natriuretic peptide (ANP) release stimulated by angiotensin II (Ang II) (10(-7) M) in superfused sliced rat atrial tissue. The use of N(G)-nitro-L-arginine methyl ester (L-NAME) at 10(-4) M, an inhibitor of nitric oxide synthase did not modify basal ANP release. In presence of Ang II (10(-7) M), we observed that L-NAME enhanced ANP secretion induced by Ang II. Furthermore, cGMP levels increased significantly in the presence of Ang II and was attenuated by L-NAME. On the other hand, the perfusion of 8 bromo-cGMP (10(-5) M) with Ang II reduced the effect of this octapeptide on ANP secretion. Secondly, we evaluated the effect of authentic NO on ANP release and observed that perfusion of NO reduced significantly the effect of Ang II on ANP release. We propose that the effect of Ang II on ANP secretion was modulated by NO likely via cGMP pathway.

Prognostic value of neurohormonal activation and cardiopulmonary exercise testing in patients with chronic heart failure

We compared the value of plasma neurohormones and cardiopulmonary exercise testing for predicting long-term prognosis in patients with moderate congestive heart failure (CHF). We studied 264 consecutive patients with CHF due to left ventricular systolic dysfunction. Plasma atrial natriuretic peptide (ANP), norepinephrine, and endothelin-1 were measured at rest in all patients, who also underwent a symptom-limited maximal exercise with oxygen consumption (VO(2)) determination. After a median follow-up of 789 days, 52 deaths and 31 heart transplantations occurred, of which 4 were urgent. In an univariate analysis, New York Heart Association functional class, systolic blood pressure at rest, left ventricular end-diastolic diameter, left ventricular ejection fraction, peak VO(2), percent of predicted peak VO(2), plasma ANP, plasma norepinephrine, and plasma endothelin-1 were associated with survival without urgent heart transplantation. In a multivariate stepwise regression analysis, only plasma ANP (p = 0.0001), left ventricular ejection fraction (p = 0.007), and plasma norepinephrine (p = 0.035), but neither peak VO(2) nor percentage of predicted peak VO(2), were independent predictors of death or urgent heart transplantation. Determination of plasma ANP and norepinephrine provides additional independent information for long-term prognostic determination compared with exercise testing alone. Measurement of plasma neurohormones should therefore be considered routinely as a complementary or alternative tool for identifying high-risk patients with moderate CHF.

Plasma adrenomedullin, a new independent predictor of prognosis in patients with chronic heart failure

BACKGROUND

Adrenomedullin, a potent endogenous vasodilating and natriuretic peptide, may play an important role in the pathophysiology of chronic heart failure. Plasma levels of immunoreactive adrenomedullin were examined for prediction of prognosis in chronic heart failure.

METHODS AND RESULTS

Plasma levels of immunoreactive-ADM (ir-ADM) were measured by radioimmunoassay in 117 chronic heart failure patients with idiopathic or ischaemic cardiomyopathy (mean ejection fraction: 28 +/- 10%, in the NYHA functional class I/II/III/IV:8/73/29/7, and treated with ACE inhibitors and diuretics. Plasma levels of immunoreactive adrenomedullin were significantly increased in chronic heart failure patients by comparison to controls (618 +/- 293 pg x ml(-1) vs 480 +/- 135 pg x ml(-1), P=0.01). During the follow-up period (237 +/- 137 days) 14 cardiovascular deaths and four urgent cardiac transplantations occurred. In the univariate Cox model, immunoreactive adrenomedullin plasma levels were related to prognosis (P=0.004). A multivariate analysis including heart rate, systolic blood pressure, NYHA class, left ventricular ejection fraction, left ventricular echocardiographic end-diastolic diameter, plasma levels of immunoreactive adrenomedullin, endothelin-1, norepinephrine and atrial natriuretic peptide was performed: plasma levels of immunoreactive adrenomedullin (P=0.03), of endothelin-1 (P=0.0001), and systolic blood pressure (P=0.003) were significantly associated with outcome.

CONCLUSION

Our results suggest that elevated plasma levels of immunoreactive adrenomedullin are an independent predictor of prognosis in predominantly mild to moderate chronic heart failure treated by conventional therapy and provide additional prognostic information.

Effect of cryopreservation on endothelin-1 productions of human mammary artery

The aim of this study was to determine the ability of human mammary artery cells to maintain a metabolic activity by measuring the artery concentration of two vasoactive substances, endothelin-1 (ET-1) and cyclic guanosyl monophosphate (cGMP), and a neurohumoral substance-neuropeptide Y (NPY)-prior to and following cryostorage. Ten distal segments of internal mammary arteries were obtained at the time of surgery in patients who had undergone coronary artery bypass grafting. One ring of each vessel served as a fresh control for the other ring that was used in cryopreservation experiments. The arteries were frozen with liquid nitrogen at a controlled rate down to -130 degrees C with an automatic freezing machine and were then stored in a liquid nitrogen vapor at -150 degrees C. After mammary artery extraction, ET-1, cGMP, and NPY concentrations were studied before and after cryopreservation. Cryopreserved, compared to fresh arteries, exhibited an increase in ET-1 (11.11+/-1.61 vs. 3. 09+/-0.06 pg/mg; p=0.004) and a decrease in cGMP (9.88+/-2.04 vs. 8. 55+/-2.07 p moles/mg; p<0.02), whereas there was no significant NPY variation. An increase in ET-1 and decrease in cGMP was found in 10 out of 10 and 6 out of 10 of cryopreserved artery specimen, respectively. There was no significant correlation between ET-1 and cGMP production in fresh or in cryopreserved arteries. The present method of cryostorage is effective in preserving "hormonal" mammary artery activity. However, the particularly high ET-1 concentration without associated cGMP concentration may be deleterious by increasing smooth-muscle cell proliferation and vascular tone of cryopreserved arteries.

Release of neuropeptide Y and hemodynamic changes during surgical removal of human pheochromocytomas

This study investigates the release of Neuropeptide Y from eight human pheochromocytomas. Profil immunoreactive Neuropeptide Y (Ir-NPY) levels during the management of surgery were compared with these of norepinephrine (NE) while hemodynamics were monitored. Plasma IrNPY and NE levels increased during tumor manipulation and returned to near normal one hour after operation. However, Ir-NPY levels remained high just after tumor resection while NE levels were significantly decreased. At tumor manipulation and just after tumor resection, plasma Ir-NPY levels were correlated with the systemic vascular resistances (SVR) (r = 0.74; P<0.04 and r = 0.86; P<0.006 respectively). No correlation was found either between plasma Ir-NPY and NE levels or between plasma NE levels and SVR. The release of Ir-NPY from tumor tissue, studied by a superfusion method, exhibited a significant correlation with the plasma Ir-NPY concentrations at the time of corresponding tumor resection (r = 0.95; P<0.007). Chromatographic analysis showed that Ir-NPY in plasma and outflow migrate as human NPY (1-36). These results confirmed that in pheochromocytoma, plasma NPY mainly originates from the tumor and argue for an important role of NPY in pheochromocytoma hypertension as indicated by the correlation between the Ir-NPY levels and the SVR.

Effects of a three-day head-down tilt on renal and hormonal responses to acute volume expansion

To clarify whether exposure to 6 degrees head-down tilt (HDT) leads to alterations in body fluid volumes and responses to a saline load similar to those observed during space flight we investigated eight healthy subjects during a 4-day, 6 degrees HDT and during a time-control ambulatory period with cross-over. Compared with the ambulatory period, HDT was associated with greater urinary excretion of water and sodium (UV, U(Na)V) from 0 to 12 h (cumulated UV 1,781 +/- 154 vs. 1,383 +/- 170 ml, P < 0.05; cumulated U(Na)V 156 +/- 14 vs. 117 +/- 9 mmol, P < 0.05), and with higher plasma atrial natriuretic factor (ANF) at 4 h. Hemoglobin and hematocrit increased over the first 24 h, and blood and plasma volumes were decreased after 48 h of HDT (P < 0.05). Plasma renin activity (PRA) and aldosterone did not differ between the two groups. With prolongation of HDT, UV and U(Na)V returned close to baseline values. On the fourth HDT day, a 30-min infusion of 20 ml/kg isotonic saline was performed, while a large oral water load maintained a high urine output. The ambulatory period experiment was done with the subjects in the acute supine posture. Sodium excreted within 4 h of loading was 123 +/- 8 mmol during HDT vs. 168 +/- 16 mmol during the ambulatory period (P < 0.05). The increase in plasma ANF and decrease in PRA were greater during HDT than during the ambulatory period (ANF 30 +/- 5 vs. 13 +/- 4 pg/ml, P < 0.05; PRA -1.4 +/- 0.4 vs. -0.5 +/- 0.2 ng. ml(-1). h(-1), P < 0.05). Our data suggest that after a 3-day HDT period, thoracic volume receptor loading returns to the level seen in the upright position, leading to blunted responses to volume expansion, compared with acute supine control.

[Role of cardiac aldosterone in post-infarction ventricular remodeling in rats]

Synthesis of aldosterone (Aldo) and corticosterone (B) has been recently reported in rat heart. However, regulation of this synthesis in pathophysiological states remains unknown. Thus, this study aimed to analyze effects of a one-month myocardial infarction (MI) on cardiac steroidogenic system. Levels of terminal enzymes of B (11 beta-hydroxylase: 11 beta H) and aldo (Aldo-synthase: AS) synthesis were assayed by quantitative RT-PCR. Cardiac Aldo and B levels were assessed by celite colum chromatography and radioimmunoassay. MI raised AS mRNA levels by 2.0-fold (p < 0.05) but downregulated that of 11 beta H by 2.4 fold (p < 0.05) in the noninfarcted part of the left ventricle (LV). Cardiac steroids production followed a similar pattern of regulation. Aldo level was increased in MI (319 +/- 85 vs 87 +/- 11 pg/mg of protein in control, p < 0.05) whereas that of B fell (2,412 +/- 318 vs 4,624 +/- 857 pg/mg of protein in control, p < 0.05). MI also induced an 1.9-fold increase in cardiac Ang II level. Such cardiac regulations were prevented by Ang II-AT1 receptor antagonist losartan (8 mg/kg/day) treatment. The Aldo receptor antagonist spironolactone (20 mg/kg/day) had no effect. Plasma Aldo and B, and adrenal 11 beta H and AS mRNA levels were unchanged whatever the treatment. The MI-induced collagen deposition in noninfarcted area of the LV was reduced by both spironolactone and losartan treatments by 1.6- and 2.5-fold, respectively. These data indicate that MI is associated with tissue-specific activation of myocardial aldosterone synthesis. This activation is mediated by cardiac Ang II via AT1 receptor and the resultant increase of intracardiac aldosterone level may be involved in post-MI ventricular remodeling.

Activation of cardiac aldosterone production in rat myocardial infarction: effect of angiotensin II receptor blockade and role in cardiac fibrosis

BACKGROUND

This study analyzed the regulation and the role of the cardiac steroidogenic system in myocardial infarction (MI).

METHODS AND RESULTS

Seven days after MI, rats were randomized to untreated infarcted group or spironolactone- (20 and 80 mg x kg-1 x d-1), losartan- (8 mg x kg-1 x d-1), spironolactone plus losartan-, and L-NAME- (5 mg x kg-1 x d-1) treated infarcted groups for 25 days. Sham-operated rats served as controls. In the noninfarcted myocardium of the left ventricle (LV), MI raised aldosterone synthase mRNA (the terminal enzyme of aldosterone synthesis) by 2. 0-fold and the aldosterone level by 3.7-fold. Conversely, MI decreased 11beta-hydroxylase mRNA (the terminal enzyme of corticosterone synthesis) by 2.4-fold and the corticosterone level by 1.9-fold. MI also induced a 1.9-fold increase in cardiac angiotensin II level. Such cardiac regulations were completely prevented by treatment of the infarcted heart with losartan. The MI-induced collagen deposition in noninfarcted LV myocardium was prevented by 1.6-fold by both low and high doses of spironolactone and by 2.5-fold by losartan. In addition, norepinephrine level was unchanged in infarcted heart but was attenuated by both losartan and spironolactone treatments.

CONCLUSIONS

MI is associated with tissue-specific activation of myocardial aldosterone synthesis. This increase is mediated primarily by cardiac angiotensin II via AT1-subtype receptor and may be involved in post-MI ventricular fibrosis and in control of tissue norepinephrine concentration.

Acute effects of an endothelin-1 receptor antagonist bosentan at different stages of heart failure in conscious dogs

OBJECTIVE

Inhibition by endothelin antagonist is a potential therapy in heart failure. However, the effect of endothelin inhibition during the development of heart failure has not been evaluated. The goal of our study was to examine the acute hemodynamic effects of the mixed endothelin receptor antagonist bosentan in the control state and at different stages of heart failure induced by right ventricular pacing (250 bpm) in conscious dogs.

METHODS

Nine dogs were chronically instrumented for the measurements of left ventricular pressure and its first derivative (dP/dt), cardiac output, left ventricular regional wall thickness and aortic pressure. Bosentan (3 mg/kg, i.v. bolus) and placebo were given at control, at 1 week of pacing (stage of left ventricular dysfunction with perserved cardiac output) and at 3 weeks of pacing (phase of heart failure with low cardiac output).

RESULTS

With the development of heart failure, baseline plasma endothelin level increased progressively. Placebo did not induce hemodynamic and plasma endothelin changes during the 30 min recording at any stage. At control, bosentan did not change hemodynamics. At 1 and 3 weeks of pacing, bosentan did not modify left ventricular myocardial function indices but reduced mean arterial pressure (by 7 +/- 2 and 8 +/- 1 mm Hg respectively, p < 0.005). Bosentan increased stroke volume at 3 weeks of pacing only.

CONCLUSIONS

Endothelin inhibition by endothelin antagonist bosentan, decreases aortic pressure in both early left ventricular dysfunction and in heart failure in contrast with the control state. In the phase of heart failure with low cardiac output, bosentan increases stroke volume. In the early left ventricular dysfunction, bosentan, by reducing arterial pressure, may limit the deterioration of cardiac function through a reduction of the workload imposed on the heart.

Early increase of von Willebrand factor predicts adverse outcome in unstable coronary artery disease: beneficial effects of enoxaparin. French Investigators of the ESSENCE Trial

BACKGROUND

The pathogenesis of unstable angina and non-Q-wave myocardial infarction is still poorly understood, and early evaluation of prognosis remains difficult. We therefore studied the predictive value of 5 biological indicators of inflammation, thrombogenesis, vasoconstriction, and myocardial necrosis, and we examined the effects of enoxaparin and unfractionated heparin on these markers after 48 hours of treatment.

METHODS AND RESULTS

Sixty-eight patients with unstable angina or non-Q-wave myocardial infarction randomized in the international ESSENCE trial participated in this French substudy. C-reactive protein, fibrinogen, von Willebrand factor antigen, endothelin-1 and troponin I were measured on admission and 48 hours later. The composite end point of death, myocardial infarction, recurrent angina, or revascularization was significantly lower at 14 and 30 days of follow-up in patients allocated to enoxaparin compared with unfractionated heparin. All acute-phase reactant proteins were elevated on admission and increased further at 48 hours. Multivariate analysis demonstrated that the rise of von Willebrand factor over 48 hours was a significant and independent predictor of the composite end point at both 14 days and 30 days. Moreover the early increase of von Willebrand factor was more frequent and more severe with unfractionated heparin than with enoxaparin (mean change was +8.7+/-8.8% with enoxaparin versus +93.9+/-11.7% with unfractionated heparin, P<0.0001). The other clinical and biological variables did not predict outcome.

CONCLUSIONS

In patients with unstable angina or non-Q-wave myocardial infarction, the acute-phase proteins increase over the first 2 days despite medical treatment. The early rise of von Willebrand factor is an independent predictor of adverse clinical outcome at 14 days and at 30 days. Enoxaparin provides protection as evidenced by the reduced release of von Willebrand factor, which represents a favorable prognostic finding.

Endothelin-1 is synthesized and inhibits cyclic adenosine monophosphate- dependent anion secretion by an autocrine/paracrine mechanism in gallbladder epithelial cells

Ion and fluid transport across the biliary epithelium contributes to bile secretion. Since endothelin (ET)-1 affects ion transport activities and is released by human gallbladder- derived biliary epithelial cells in primary culture, we examined the expression of ET peptides and ET receptors and the influence of ET-1 on ion transport in this epithelium ex vivo. In freshly isolated gallbladder epithelial cells, preproET-1, -2, and -3 mRNAs were detected by reverse transcription PCR and ET-1 isopeptide was identified by chromatography. The cells also displayed ET receptor mRNAs and high-affinity binding sites for ET-1, mostly of the ETB type. Electrogenic anion secretion across intact gallbladder mucosa was stimulated by forskolin, secretin, and exogenous ATP, as assessed by short-circuit current (Isc) increases in Ussing-type chambers. ET-1 inhibited forskolin- and secretin-induced changes in Isc, without affecting baseline Isc or ATP-induced changes. Accordingly, ET-1 significantly reduced the accumulation of intracellular cAMP elicited by forskolin and secretin in the epithelial cells, and this effect was abolished by pertussis toxin. This is the first evidence that ET-1 is synthesized and inhibits, via a Gi protein-coupled receptor, cAMP-dependent anion secretion in human gallbladder epithelium, indicating a role in the control of bile secretion by an autocrine/paracrine mechanism.

Modifications of myocardial Na+,K(+)-ATPase isoforms and Na+/Ca2+ exchanger in aldosterone/salt-induced hypertension in guinea pigs

OBJECTIVE

The aim of this study was to determine whether changes in cardiac Na+,K(+)-ATPase subunits and Na+/Ca2+ exchanger expression are regulated in aldosterone-salt hypertensive guinea pigs.

METHODS

Guinea pigs (GP) were unilaterally nephrectomized and randomized into three groups (aldosterone-salt; control-salt; control). After 90 days of treatment, echocardiographic M-mode assessment and right carotid arterial catheterization were performed in vivo, and plasma hormones and electrolytes were measured. mRNA and protein levels were studied by Northern and Western blot analysis.

RESULTS

Aldosterone-salt treatment induced, (1) arterial hypertension (+40%) and LV hypertrophy (+60%) without altering LV-fractional shortening, (2) an increase in plasma norepinephrine levels (+262%) and suppression of renin activity. Northern blot analysis showed the presence of the mRNA encoding the three alpha isoforms and the beta 1 subunit of Na+,K(+)-ATPase in GP myocardium. In the aldosterone-salt group, levels of alpha 1 and beta 1 mRNAs were unchanged. alpha 2 mRNA was increased in both ventricles, whereas alpha 3 mRNA was increased in hypertrophied LV only. Furthermore, levels of the Na+/Ca2+ exchanger mRNA were decreased in both ventricles. At protein level, the two major transcripts (alpha 1 and alpha 2) were detected but alpha 3 isoform was not. Parallel changes in protein and mRNA accumulation of alpha 1 and alpha 2 isoforms were observed in hypertrophied LV.

CONCLUSION

These results show that alpha 1 and alpha 2 isoforms are expressed in GP heart and that they are independently regulated in aldosterone-salt hypertension. Like the alpha 1 isoform in renal tissue, alpha 2 isoform is the main target of aldosterone-salt. Reciprocal expression of the Na+/Ca2+ exchanger and Na+,K(+)-ATPase suggests an adaptational mechanism which maintains an appropriate sodium gradient and calcium concentration in hypertensive myocardium.

Effects of ANF infusion on the renal responses to lower-body negative pressure in humans

To investigate the role of atrial natriuretic factor (ANF) in renal responses to a decrease in central blood volume, we examined the effects of ANF infusion on renal function and hormones during prolonged lower-body negative pressure (LBNP). Ten healthy volunteers participated in two experimental sequences, each comprising a 120-min baseline period followed by the application of -20 mm Hg LBNP for 90 min. During one of the two sequences, ANF was infused throughout LBNP application at the constant rate of 2.5 ng/kg/min. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by using inulin and p-aminohippuric acid clearance techniques. LBNP induced a significant decrease in ERPF (534 +/- 28 to 457 +/- 26 ml/min; p < 0.05), GFR (120 +/- 2.5 to 112 +/- 2.5 ml/min; p < or = 0.01), in urine excretion (12 +/- 0.9 to 5.6 +/- 0.5 ml/min; p < 0.001), in sodium excretion (0.36 +/- 0.03 to 0.30 +/- 0.02 mmol/min; p < 0.05), and in plasma ANF (19 +/- 3 to 11 +/- 2 pg/ml; p = 0.001) concomitant with an increase in plasma renin activity (PRA; 0.48 +/- 0.09 to 0.87 +/- 0.16 ng/ml/h; p = 0.01) and of forearm vascular resistance (FVR; p < 0.05). The combination of ANF infusion with LBNP led to a slight increase in plasma ANF from baseline (from 20 +/- 2 to 28 +/- 3 pg/ml; p < 0.05). Compared with values obtained during LBNP with saline vehicle infusion, values obtained during LBNP with ANF infusion were similar for ERPF (463 +/- 23 vs. 457 +/- 26 ml/min), for GFR (111 +/- 2 vs. 112 +/- 2 ml/min), and for urine excretion (7 +/- 0.6 vs. 5.6 +/- 0.5 ml/min; p = 0.07), but greater for fractional excretion of sodium (2.38 +/- 0.25% vs. 1.91 +/- 0.11%; p < 0.05) and FVR (p < 0.05), and smaller for PRA (0.49 +/- 0.1 vs. 0.87 +/- 0.16 ng/ml/h; p < 0.01). These data show that ANF infusion attenuates the antinatriuretic effect of low-level LBNP and its PRA-increasing effects without altering renal hemodynamic responses to LBNP, although there is a decrease in the LBNP-induced forearm vasoconstriction. These results were obtained with plasma ANF levels slightly higher than those in baseline. They support the hypothesis that a decrease in ANF secretion might contribute to the antinatriuretic effect of LBNP.

Chemical modifications of the vasoconstrictor peptide angiotensin II by nitrogen oxides (NO, HNO2, HOONO)--evaluation by mass spectrometry

Nitric oxide (NO) and angiotensin II are natural regulators of blood pressure. Under aerobic conditions, NO is transformed into its higher oxides (N2O4, NO2, NO/NO2 or N2O3) and oxoperoxonitrate (currently named peroxynitrite) by coupling with superoxide. Previous studies have shown that these reactive nitrogen species should be involved in vivo in the transformation of cysteine and tyrosine into the corresponding nitrosothiol and 3-nitrotyrosine. In the present study, attention has been focused on the relative reactivities of HNO2, peroxynitrite, and NO in the presence of dioxygen, towards the arginine and tyrosine residues of the peptide angiotensin II. Nitration of the tyrosine residue is clearly the main reaction with peroxynitrite. By contrast, besides 20% of nitration of the tyrosine residue, NO in the presence of dioxygen leads to nitrosation reactions with the arginine residue similar to those observed with HNO2 at pH 5, possibly through the intermediate N2O3 reactive species. Angiotensin II is converted for the most part to peptides having lost either a terminal amine function or the whole guanido group, leading respectively to citrulline-containing angiotensin II or to a diene derivative. Identification established mainly by tandem mass spectrometry of peptidic by-products allows us to propose a cascade of nitrosations of all the amine functions of the arginine residue. Further in vivo studies show that transformations of the arginine residue in angiotensin II do not alter its vasoconstrictive properties, whereas nitration of the tyrosine residue totally inhibits them.

Cellular localization of endothelin-1 and increased production in liver injury in the rat: potential for autocrine and paracrine effects on stellate cells

Endothelin (ET) peptides have been implicated in the pathogenesis of several biological processes within the liver. ET levels are elevated in the circulation of patients with cirrhosis, and recent data suggest that ET may be overproduced in the liver itself in this condition. The aims of the current study were to elucidate the cellular source and expression of endothelin-1 (ET-1) in normal and injured liver, and to investigate its biological effects on stellate cells, the primary target of ETs in the liver. In normal hepatic cells, preproET-1 messenger RNA (mRNA) was detected in only nonparenchymal cells, predominantly in sinusoidal endothelial cells. After biliary fibrosis and early cirrhosis induced by bile duct ligation, preproET-1 mRNA and immunoreactive ET levels increased with progressive injury in whole liver extracts, as well as in isolated stellate and endothelial cell fractions. Eight days after bile duct ligation, the relative increase in preproET-1 mRNA was 1.6- and 7.6-fold above normal in sinusoidal endothelial and stellate cells, respectively. Additionally, immunoreactive ET peptide levels increased by 60% +/- 27% over basal values in sinusoidal endothelial cells and 98% +/- 40% in stellate cells. Cultured stellate cells responded dramatically to exogenous ET-1 by the spreading and up-regulation of smooth muscle alpha actin expression. Furthermore, in early culture before cellular activation, ET-1 (10 nmol/L) caused over a twofold increase in [3H]thymidine incorporation, while activated cells (i.e., those cultured for >1 week) exposed to ET-1 exhibited up to a fivefold decrease in [3H]thymidine incorporation. The data indicate that not only is ET-1 overproduced by both sinusoidal endothelial and stellate cells during liver injury, but that it also has potent effects on features of stellate cell activation. We conclude that autocrine and paracrine production of ET-1 is prominent and is likely to be important in the pathogenesis of hepatic diseases.

Renal and vascular effects of C-type and atrial natriuretic peptides in humans

C-type natriuretic peptide (CNP) may affect renal and vascular functions differently from atrial natriuretic peptide (ANP). The objective of this study was to compare the renal and vascular actions of CNP to those of ANP in normal men. CNP or ANP (0.005, 0.01, and 0.05 microg x kg(-1) x min(-1)) were given by infusion to eight healthy volunteers. CNP caused dose-dependent increases in natriuresis (U(Na)) and in the fractional excretion of sodium (FE(Na)) with no effect on diuresis (UV), renal plasma flow, and glomerular filtration rate (GFR). Fraction of filtration (FF) increased only with the 0.05 microg x kg(-1) x min(-1) CNP dose. ANP caused larger increases in U(Na), FE(Na), and FF than CNP and also increased UV at 0.01 and 0.05 microg x kg(-1) x min(-1) and GFR at 0.05 microg x kg(-1) x min(-1). Although the ANP and CNP infusions produced similar elevation in the respective peptides plasma levels, urinary and nephrogenous guanosine 3',5'-cyclic monophosphate increased less in response to CNP than to ANP. Blood pressure, forearm blood flow, plasma renin activity, and aldosterone remained unaffected during the peptides infusion. Plasma ANP increased slightly during CNP infusion. Our data indicate a higher threshold of renal response to CNP than to ANP. In contrast to ANP, CNP probably may not act as an endocrine factor in humans.

Angiotensin II-induced phosphoinositide production and atrial natriuretic peptide release in rat atrial tissue

The effect of angiotensin II (Ang II) on inositol phosphate (IP) production and atrial natriuretic peptide (ANP) release was studied in sliced rat atrial tissue. The ability of Ang II (10(-7) M) to stimulate IP accumulation was detected after 1 min of incubation, and the maximal increase was observed at 5 min. In (2-3H) inositol-labeled atrial tissue, Ang II induced the formation of (2-3H) inositol monophosphate (IP1) in a dose-dependent manner. The effect of Ang II (10(-7) M) on IP1 was prevented by losartan (10(-7) M) but was not affected by PD123319 (10(-7) M). Similar effects were observed on Ang II-induced ANP release in the presence of these antagonists. The mechanism of ANP liberation induced by this peptide was independent of cyclic adenosine monophosphate (cAMP) and regulated by nitric oxide (NO). The role of Ca2+ in the effect of Ang II was tested by 1,2-bis (o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester (BAPTA-AM; 10(-5) M), a chelator of intracellular Ca2+ that prevented the release of ANP by Ang II stimulation. We concluded that Ang II induced IP production and ANP release through AT1 receptors. Stimulation of ANP release by Ang II was dependent on intracellular Ca2+.

Prognostic value of plasma endothelin-1 in patients with chronic heart failure

AIMS

Endothelin-1 is a potent vasoconstrictive and multifunctional peptide. Elevated concentrations have been reported in congestive heart failure. We hypothesized that the level of endothelin-1 in plasma is a prognostic marker in congestive heart failure.

METHODS AND RESULTS

Plasma levels of endothelin-1 were measured by radioimmunoassay in 120 congestive heart failure patients with ischaemic or non-ischaemic cardiomyopathy (mean ejection fraction 28 +/- 11%, in New York Heart Association (NYHA) functional class I:21, class II 35, class III: 61, class IV: 3). During a median follow-up of 361 +/- 338 days, 14 cardiac deaths occurred. In the univariate Cox model, endothelin-1 was the most powerful prognostic marker among the variables tested (P = 0.0001). A multivariate model, including plasma atrial natriuretic peptide and noradrenaline, NYHA class, age, and echocardiographic left ventricular end-diastolic diameter index was highly predictive of mortality (P = 0.00008), but only endothelin-1 remained significantly associated with outcome (P = 0.02). Patients with plasma endothelin-1 > or = 5 pg. ml-1 had a higher mortality rate than those with endothelin-1 < 5 pg. ml-1 (21% vs 4%, P = 0.001).

CONCLUSION

Our results suggest that elevated endothelin-1 plasma levels are associated with a poor prognosis and routine plasma endothelin-1 determination provides important prognostic information in mild to moderate heart failure.

Endothelin-1 in the lungs of patients with pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is characterized by an increase in vascular tone and an abnormal proliferation of muscle cells in the walls of pulmonary arteries. Recent studies have found high plasma endothelin-1 (ET-1) concentrations in patients with PH. This study was conducted to assess whether elevated circulating ET-1 levels in PH really reflect excessive local pulmonary production.

METHODS

We prospectively studied ET-1 concentration in lung specimens from 6 control subjects and 13 patients with severe PH referred for lung or heart-lung transplantation (6 patients had primary PH and 7 PH secondary to congenital heart defect). Endothelin-like immunoreactivity (ET-LI) was measured in plasma and lung tissue, using a radioimmunoassay, after ET-1 extraction. Reverse-phase high-performance liquid chromatography was also performed.

RESULTS

Peripheral venous plasma ET-LI concentrations in patients with PH, whatever the cause, were greater than those in controls (10.7 +/- 0.8 vs 5.3 +/- 0.7 pg/ml; P < 0.0005). Pulmonary ET-LI was significantly higher in patients with PH, irrespective of its cause, than in controls (25.2 +/- 5.1 vs 8.1 +/- 1.1 pg/mg, P < 0.03). ET-LI pulmonary concentrations were slightly higher in Eisenmenger than in primary PH, but this was not significant (27.1 +/- 8.6 vs 22.8 +/- 5.4 pg/mg). Linear regression analysis indicated a small but significant correlation between ET-LI pulmonary concentrations and pulmonary vascular resistance in the patients with PH (r = 0.38; P = 0.047). In each case, HPLC separation of ET indicated that most of the immuno-reactivity was detected in the same fraction as ET-1.

CONCLUSIONS

The striking increase in ET-1 pulmonary concentration provides new evidence that excessive local pulmonary ET-1 production may contribute to the vascular abnormalities of pulmonary hypertension.

Hemodynamic and neurohormonal effects of flosequinan in patients with heart failure

In a double-blind, placebo-controlled study, the central and peripheral hemodynamic effects of 100 mg oral flosequinan and the impact of this drug on neurohormonal activation were noninvasively evaluated in 18 patients with congestive heart failure, after the first administration and after 10 days of treatment. No significant hemodynamic and neurohormonal changes were observed after acute administration. After 10 days, flosequinan produced central and peripheral hemodynamic improvement characterized by an increase in left ventricular circumferential fiber shortening velocity (+12%), a decrease in total systemic resistance (-36%), and an increase in leg blood flow (+37%). No significant changes were observed in heart rate and arterial pressure in patients receiving flosequinan, though a slight increase in heart rate (+17%) was recorded. Despite these favorable hemodynamic effects, flosequinan significantly increased plasma norepinephrine (+38%) and plasma renin activity (+13%) after 10 days of treatment. Thus, the beneficial central and peripheral hemodynamic effects of flosequinan are accompanied by activation of the sympathetic and reninangiotensin systems. This might be related to the unfavorable effects of the drug on survival in patients with heart failure.

Captopril does not acutely modulate plasma endothelin-1 concentration in human congestive heart failure

Congestive heart failure (CHF) is a syndrome characterized by increased levels of angiotensin II (Ang II) and endothelin-1 (ET-1). In vitro, Ang II stimulates ET-1 release. The purpose of the study was to assess the effect of a single dose of an angiotensin-converting enzyme inhibitor (ACEI) captopril versus placebo on plasma endothelin concentration in human congestive heart failure. Captopril (25 mg, given orally) was compared with placebo in a group of 20 patients with systolic dysfunction in a double-blind randomized study. Plasma irET concentration was significantly increased in CHF patients compared with normal subjects (5.59 pg/ml +/- 0.35 vs. 3.58 pg/ml +/- 0.99, p < 0.0002). Despite the decrease in systolic blood pressure and the increase in plasma renin activity, suggesting a significant blockade of the renin-angiotensin system, no difference in plasma irET-1 was observed between captopril and placebo. Our results suggest that captopril does not acutely influence irET-1 plasma concentration in human CHF. These data do not support the hypothesis that the acute vasodilator effect of a single dose of 25 mg of captopril given daily orally involves modulation of the increased plasma concentration of endothelin observed in CHF.

Acute and long-term dose-response study of quinapril on hormonal profile and tissue angiotensin-converting enzyme in Wistar rats

Therapeutic response to angiotensin-converting enzyme (ACE) inhibitors was reported to be better related to tissular than to circulating levels of ACE inhibition, especially during chronic therapy. We studied the relations between plasma concentrations of angiotensin I (AI), plasma renin activity (PRA), angiotensin II (AII), and aldosterone (by radioimmunoassay, RIA) and levels of serum and tissue ACE activities during acute and chronic quinapril administration in rats. Forty-eight male Wistar rats received quinapril by gavage for either 1 day (n = 24) or 15 days (n = 24) at different doses (control, 0.1, 1, and 10 mg/kg/day; 6 rats at each dose). Plasma hormonal parameters, serum, and tissue (lung, heart, and aorta) ACE activities were measured 3 h after the last gavage. Significant dose-dependent inhibitions of serum and lung ACE during acute and chronic treatments were observed (p < 0.05). Degrees of serum and heart ACE inhibition (at 0.1 mg/kg/day) were significantly lower with chronic than with acute treatment (p < 0.05). Degree of inhibition in lung, which represents the main source of total ACE, was similar during acute and chronic treatments. Among plasma hormonal parameters, plasma AI was correlated to PRA and showed the best correlation with ACE inhibition. After logarithmic transformation, log AI was significantly correlated to ACE activity in lung during chronic treatment (r = -0.85, p < 0.05). This parameter may provide a useful index for ACE inhibitor dosage adjustment during chronic therapy.

Decrease in internal jugular endothelin levels after carotid cross-clamping during human carotid revascularization procedures

Endothelin-1 (ETL-1), a peptide recently isolated from vascular endothelial cells, acts in cerebral arteries in vitro as a potent and long-lasting vasoconstrictor and has been implicated in the development of cerebral vasospasm. To ascertain whether this new vasoconstrictor has any effect on regulation of the cerebral circulation, we measured plasma ETL-1 concentrations in patients undergoing carotid revascularization and attempted to correlate the variations of venous and arterial plasma ETL-1 with the characteristics of the procedure, including cerebral vasospasm. We prospectively studied 11 patients undergoing a total of 14 carotid surgical revascularization procedures (12 endarterectomies, 2 polytetrafluoroethylene bypass grafts from the common to the internal carotid arteries). Before carotid cross-clamping, blood samples were drawn from the internal jugular vein and the healthy common carotid artery proximal to the occlusive lesion to be treated. After endarterectomy, blood samples were withdrawn from the internal, external, and common carotid arteries. After the release of the last clamp, a final aliquot of blood was withdrawn from the internal jugular vein. After plasma extraction on a C2-ethyl microcolumn, plasma endothelin-like immunoreactivity was measured by means of radioimmunoassay with a polyclonal antibody. In 9 of the 11 patients, internal jugular vein ETL-1 concentration decreased statistically significantly after carotid artery cross-clamping (4.2 +/- 1.4 pg/ml vs. 3.9 +/- 1.1 pg/ml; p < 0.05). In the 2 patients in whom ETL-1 levels failed to drop, a shunt was used during the procedure in 1, and the other was the only patient who had an ipsilateral ischemic postoperative stroke. The decrease in internal jugular vein ETL-1 concentration failed to correlate with any of the cross-clamping times. The level of arterial blood ETL-1 remained steady in the common carotid artery before and after cross-clamping (4.5 +/- 1.5 pg/ml vs. 4.6 +/- 0.9 pg/ml). A small, nonsignificant decrease in ETL-1 level was noted in the external and internal carotid arteries after cross-clamping. The decrease in internal jugular vein ETL-1 levels may in part reflect a compensatory response to carotid artery cross-clamping, which could limit the reduction of local cerebral blood flow.

Cellular mechanism of angiotensin II-induced atrial natriuretic peptide release in rat right atrial tissue

This study presents an investigation of the mechanism of angiotensin II (Ang II)-induced atrial natriuretic peptide (ANP) release in superfused sliced right atria of rats. Ang II (0.1 microM) enhanced ANP release by 49%. This phenomenon was significantly blocked by (Sara1-Ileu 8) Ang II (1 microM) and losartan (0.1 microM). The use of neomycin (100 microM), a phospholipase-C inhibitor completely suppressed the effect of Ang II on ANP increase. To elucidate the intracellular mechanism of ANP released by Ang II, the role of protein kinase C (PKC) was determined by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) and phorbol ester : 4-beta-phorbol 12-myristate-13-acetate (PMA). We observed that PMA (0.1 microM) stimulated ANP release whereas H-7 (10 microM), an inhibitor of PKC in the presence of Ang II, prevented ANP increase. The role of calcium was also evaluated with 8-(N-N-diethylamino)-ocytyl-3,4,5, trimethoxy-benzoate (TMB-8) (10 microM) and N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide (W-7) (10 microM), which completely inhibited ANP release by Ang II. Pre-treatment with diltiazem (10 microM), an antagonist of the Ca++ channel, did not prevent ANP increase due to Ang II, but A23187 (5 microM) enhanced ANP release by Ang II. These results suggest that PKC and intracellular calcium play an important role in ANP release under the influence of Ang II in rat atrial tissue.

Plasma levels and molecular forms of proatrial natriuretic peptides in healthy subjects and in patients with congestive heart failure

A specific and sensitive radioimmunoassay (RIA) for the N-terminal fragment of proatrial natriuretic peptide (NproANP) was developed. Antiserum raised in rabbits against a mixture enriched with prohormone was 100% cross-reactive with human proANP(1-30). Plasma concentrations of proANP(1-30) and ANP immunoreactivities (ir-) were simultaneously measured in healthy subjects and patients with congestive heart failure (CHF; 26 dilated cardiomyopathy and 5 ischemic heart disease). High plasma levels of both ir-proANP(1-30) and ir-ANP were detected in CHF patients. Circulating ir-ANP levels were elevated in New York Heart Association functional Classes II and III patients but not in Class I patients. However, plasma levels of ir-proANP(1-30) were higher in asymptomatic patients than in healthy subjects, and markedly increased in patients of Classes II and III. Analysis of ir-proANP(1-30) by gel filtration chromatography or reverse-phase high pressure liquid chromatography revealed a 10 kDa peptide circulating as a distinct entity. These findings indicate that: (i) the most probable form of NproANP in human plasma is a 10 kDa peptide and (ii) in CHF patients the rise in plasma ir-proANP(1-30) levels is more pronounced than the variation in plasma ir-ANP. Thus, NproANP plasma levels may prove to be a more sensitive marker of left ventricular dysfunction than ANP.

Alterations in atrial natriuretic peptide gene expression during endurance training in rats

Spontaneous and experimental rises of intracardiac pressure and/or volume increase the level of atrial natriuretic (ANP) mRNA in rat atrial tissue. There is expanding evidence that ANP synthesis is increased in the ventricle under such conditions. However, little is known with regard to the myocardial ANP synthesis response to physical training. In this study, plasma and atrial immunoreactive ANP concentrations were measured in Sprague-Dawley rats trained on a treadmill and compared to sedentary controls. Atrial natriuretic peptide mRNA was detected in the heart cavities of each group by dot-blot hybridization analysis. Physical training reduced the mean immunoreactive ANP plasma levels from 405 +/- 99 to 303 +/- 45 ng/l (p < 0.05). Immunoreactive ANP in the left atrium was depleted after endurance training, while immunoreactive ANP concentration in the right atrium was unaffected. Physical training resulted in a 70% (p < 0.01) rise in ANP mRNA of the right atrium, while no changes in the other compartments were found. These data indicate that during physical training: ANP mRNA does not increase in ventricles; despite depletion of immunoreactive ANP in the left atrium, no corresponding changes of ANP mRNA are detected; and ANP mRNA increases in the right atrium while its immunoreactive ANP does not. These findings suggest that during chronic exercise the ratio between immunoreactive ANP and ANP gene expression in the atria may be altered.

Myocardial production of prostaglandins: its role in atrial natriuretic peptide release

In recent years, considerable evidence has been accumulated on prostaglandins (PG) in modulating atrial natriuretic peptide (ANP) release. In the current study we investigated whether eicosanoids promote isoproterenol-induced ANP secretion from superfused rabbit sliced atria. Inclusion of the cyclooxygenase inhibitor indomethacin (10 mumol) to the superfusing medium abolished isoproterenol-induced ANP release. Next, PGE2, but not PGF2 alpha or PGI2 (10 mumol), increased ANP release. Furthermore, isoproterenol-induced PGE2 formation was fully attenuated by indomethacin. Dibutyl-cAMP (0.5 mmol) had no effect on PGE2 formation, and the protein kinase A (PKA) inhibitor H89 (20 mumol) did not alter isoproterenol-induced PGE2 formation. On the other hand, indomethacin led to a significant decrease in isoproterenol-induced cAMP production. In addition, PGE2 enhanced basal cAMP concentration in superfusates. Superfusion of sliced atria by forskolin (10 mumol) or by dibutyl-cAMP (0.5 mmol) produced a significant rise in ANP release. Finally, H89 was ineffective on basal ANP release but abolished the increase of ANP release in response to isoproterenol or to PGE2. We conclude that: the effect of isoproterenol on ANP release is sensitive to indomethacin and H89; PGE2, but not PGE2 alpha or PGI2, increases ANP release; isoproterenol promotes myocardial PGE2 formation independently of adenylate cyclase and PKA activation pathways; and PGE2-induced ANP release is mediated by cAMP production and subsequent PKA activation. These results suggest that isoproterenol-induced ANP release appears to be mediated at least partly by PGE2 with underlying cAMP formation and PKA activation.

Blood and peritoneal levels of endothelin in continuous ambulatory peritoneal dialysis patients

We have determined the plasma levels of endothelin-1 (ET-1) in patients with end-stage renal disease treated with continuous ambulatory peritoneal dialysis (CAPD). In 10 CAPD patients mean plasma ET levels (7.01 +/- 0.5 pg/ml) were found higher than in normal subjects (3.6 +/- 0.6 pg/ml). Peritoneal clearance of ET-1 was 1.58 +/- 0.12 ml/min and 2.3 +/- 0.2 ml/min during an isotonic peritoneal exchange and a hypertonic exchange, respectively. Plasma ET-1 levels decreased slightly but significantly during a hypertonic 4-hour exchange (from 7.01 +/- 0.5 to 6.14 +/- 0.4 pg/ml) (p < 0.05) and were not modified by an isotonic 4-hour exchange (from 5.7 +/- 0.5 to 6.4 +/- 0.4 pg/ml). ET-1 is known to be an important vascular stimulant and thus elevated ET-1 levels may play a role in the genesis of cardiovascular complications which are the leading cause of mortality in these patients.

Effects of the calcium channel blockers, diltiazem and Ro 40-5967, on systemic haemodynamics and plasma noradrenaline levels in conscious dogs with pacing-induced heart failure

1. Calcium channel blockers increase cardiovascular morbidity and mortality in patients with left ventricular dysfunction. These adverse effects are probably related to the negative inotropic effect of calcium channel blockers and/or a neurohormonal activation. 2. The present study was designed to examine, in conscious dogs, the acute haemodynamic and sympathetic effects of diltiazem and Ro 40-5967 (a novel calcium channel blocker) in the control state and in heart failure. 3. Thirteen dogs were instrumented with a micromanometer and an aortic catheter. After completion of experiments in the control state, heart failure was induced by right ventricular pacing (250 beats min-1, 3 weeks). Diltiazem and Ro 40-5967 were given intravenously (0.8 mg kg-1 and 1.0 mg kg-1 respectively). Cardiac output was measured by a thermodilution technique. 4. In the control state, both agents decreased similarly mean aortic pressure with significant increases in heart rate, cardiac output (both +1.0 l min-1 and P < 0.001) and plasma noradrenaline (both +55%) without changes in left ventricular dP/dtmax. In heart failure, for matched decreases in mean aortic pressure, neither diltiazem nor Ro 40-5967 changed heart rate significantly; diltiazem decreased cardiac output (-0.3 l min-1, P < 0.02) and dP/dtmax (-14%, P < 0.001) while Ro 40-5967 still increased cardiac output (+0.3 l min-1, P < 0.02) although the increased amount was smaller than in the control state. Plasma noradrenaline level was increased more during diltiazem infusion (+120%) than during Ro 40-5967 infusion (+38%, P < 0.001). 5. Diltiazem and Ro 40-5967 have similar haemodynamic and sympathetic effects in the control state.Heart failure alters haemodynamic and sympathetic responses to both calcium channel blockers but the magnitude of the alteration appears to be different. Diltiazem exerts a depressant effect on cardiac function which cannot be overcome by its vasodilator effect and sympathetic stimulation, while Ro 40-5967 has little effect on cardiac function. These data suggest that novel calcium channel blockers with less depressant effect may not be detrimental in heart failure.

Rapid development of nitrate tolerance in healthy volunteers: assessment using spectral analysis of short-term blood pressure and heart rate variability

Nitrate tolerance is characterized by a loss of nitroglycerin (NTG) vasodilating and hypotensive effects during continuous administration, but is difficult to detect clinically. We hypothesized that the decrease in arterial blood pressure (BP) and the reflex sympathetic activation and tachycardia due to baroreflex deactivation associated with rapid intravenous (i.v.) infusion of NTG would be decreased during continuous NTG patch therapy as a result of tolerance to transdermal NTG. Sympathetic activation was measured as the change in amplitude of low-frequency (66-129 mHz) oscillations in BP and heart rate (HR) recorded by a noninvasive method. Eleven healthy male volunteers received rapid i.v. infusion of 0.45 mg NTG in 1 min on 3 consecutive days: before NTG patch, after 22.5 h of patch therapy, and 22.5 h after patch removal. The maximum decrease in systolic BP (SBP) and maximum reflex tachycardia as well as the sympathetic activation produced by i.v. NTG were compared during each of the three study periods. The maximum decrease in SBP was 38 +/- 8 mm Hg before NTG patch and 27 +/- 15 mm Hg during NTG patch (p < 0.05), with return to baseline values (37 +/- 13 mm Hg) after patch removal. There was no significant change in amplitude of reflex tachycardia among study periods. However, low-frequency oscillations in SBP increased by 40 +/- 31% in the absence of NTG patch and by only 9 +/- 35% after 22.5 h of patch therapy (p < 0.05). Patch removal resulted in a significant rebound increase in these oscillations (70 +/- 51%; p < 0.05 vs. baseline).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide during water deprivation or hemorrhage in rats. Relationship with arginine vasopressin and osmolarity

The concentrations of atrial natriuretic peptide (ANP) in atria, hypothalami and plasma were investigated in relation to the variations of the plasma endogenous immunoreactive arginine vasopressin (Ir-AVP) during water deprivation or hemorrhage in normal conscious Wistar rats. Furthermore, the in vitro and in vivo effect of extracellular hyperosmolarity on ANP release from right atrium and hypothalamus was examined. Water deprivation elevated circulating immunoreactive ANP (Ir-ANP: pg/ml) to 153 +/- 7 (24 h); 174 +/- 1 (48 h) from the control level (109.6 +/- 7.8). This increase in Ir-ANP concentration which correlated with atrial (r = -0.93) or hypothalamic (r = -0.87) Ir-ANP content decrease, was associated with significantly enhanced levels of plasma Ir-AVP, plasma sodium, osmolarity and hematocrit. An acute volume depletion by hemorrhage significantly reduced plasma Ir-ANP (67 +/- 8.4 pg/ml) from the sham operated level (140 +/- 18 pg/ml). Plasma Ir-AVP was elevated dramatically (207.4 +/- 53.4 pg/ml) compared with the sham operated level (8.8 +/- 2.6 pg/ml). These results, indicating the lack of correlation between plasma Ir-ANP and Ir-AVP in vivo, suggest that the ANP secretion, which is regulated mainly by plasma volume, may be modulated by a change in plasma osmolarity. Extracellular hyperosmolarity stimulated the ANP release from superfused sliced normal rat atria and hypothalami.

Differences Between Upper and Lower Limbs in Venous Endothelial Reactivity in Humans

Objective:

To determine the variability of endothelial reactivity to venostasis in the upper and lower limbs of healthy subjects.

Participants:

Ten healthy volunteers were investigated twice, at an interval of 1-week.

Main outcome measures:

Plasma concentrations of substances released from endothelial cells were determined in each limb after 10 min of venostasis in a sequential manner. Tissue plasminogen activator (tPA), plasminogen activator inhibiting factor (PAI-1), thrombin–antithrombin complexes (TAT) and D-dimers (D-Di) were used as indicators of the thrombotic process and its reactions; angiotensin converting enzyme (ACE) and endothelin-1 (ET1) were related to endothelial cell activity involved in vascular tone regulation.

Results:

No difference was observed in endothelial cell recovery following venostasis after an interval of 1 week. A significant difference in endothelial cell release was found between the upper and lower limbs and between the right and left legs.

Conclusions:

Excellent reproducibility of measurements was observed. In keeping with the higher frequency of venous thrombosis in the lower limbs, the left leg seemed to be less reactive after venostasis, and the endothelium was more reactive in the upper than in the lower limbs.

Endothelin-1 secretion by human gallbladder epithelial cells in primary culture

BACKGROUND

The three isoforms of endothelin (ET), ET-1, ET-2, and ET-3 are potent contractile agonists for smooth muscle in a wide variety of tissues including the gallbladder. There is increasing evidence that endothelin acts in a paracrine fashion, however, its cell source in the gallbladder is unclear.

EXPERIMENTAL DESIGN

To examine the production of ET by gallbladder and bile duct epithelium.

RESULTS

We show that human gallbladder epithelial cells in primary culture secrete endothelin. ET release was time-dependent, and intracellular ET was negligible, indicating de novo synthesis. Secretion was increased by physiologic concentrations of cholecystokinin. Epithelial cells lining hepatic cysts in primary culture also released ET, suggesting that the intrahepatic, as well as the extrahepatic biliary epithelium is a source of this cytokine. High performance liquid chromatography separation of the conditioned medium from both cell types showed a single peak corresponding to that of ET-1. In vivo, ET-1 was present in hepatic cyst fluid, but was not detectable in gallbladder or choledochal bile. On tissue sections, both intrahepatic and extrahepatic bile duct epithelial cells were labeled with an anti-"big" ET-1 polyclonal antibody.

CONCLUSIONS

These results suggest that ET-1 is locally produced in the biliary tract and by a paracrine route, could play a role in choledochal motility and gallbladder contraction.

[Changes in plasma endothelin during coronary spasm]

The role of endothelin, a powerful vasoconstrictor, was studied in coronary spasm. A methylergonovine stress test was performed in patients with normal coronary angiography. Patients who developed spasm (Group I, n = 6) were compared with those who did not (Group II, n = 6). Plasma endothelin was measured at 8, 11 a.m., 2 p.m., 4, 7, 9, 11 p.m. and 1 a.m. The stress test was carried out at 17 hours and an additional endothelin measurement was performed during spasm in positive cases. The clinical characteristics of the two groups were comparable especially with regards to cardiovascular risk factors. Except for the value recorded during coronary spasm, the plasma endothelin levels were significantly higher in the group with coronary spasm. A time-dependent variation was observed in both groups with higher endothelin levels in the morning. In group I the plasma endothelin levels were higher under basal conditions and during spasm in patients with spastic angina.

[Treatment of leprotic neuritis. Exclusive medical treatment or combined with decompression]

The authors consider the evolution of the treatment of leprotic neuritis based on homogenous series of numerous observations (a minimum of 250-300). These observations are well registered and documented with some results dimensioned by the classical A. L. E. R. T. tests carried out at intervals of time and verified by comparison between series only medical treatment and series of medico-surgical treatment. Considering some remote results and some comparative series, the indications of the exclusive medical treatment have been well defined, and the ones of the surgical decompression have been reduced. The early case finding of a leprotic neuritis by the mean of easy methods as well as its monitoring during its early specific treatment is essential. By this way we get an important proportion of functional results: satisfactory (50 p.c.) or interesting (20 p.c.). In the case of painful hypertrophia, the complementary decompression secure not only the functional recovery of mortricity, but also the epicritic sensibility.