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Biomedical subjects

R Moreau

Publications and source records attributed to R Moreau.

At least 127 records · Page 7Linked to original sources
PubMed1994

Effects of vasopressin on haemodynamics in portal hypertensive rats receiving clonidine.

The effects of clonidine, vasopressin or a combination of both substances on splanchnic and systemic haemodynamics were measured in conscious rats with portal vein stenosis. Clonidine alone significantly decreased portal pressure, portal tributary blood flow and cardiac index, but did not change arterial pressure. Vasopressin alone significantly increased arterial pressure and significantly decreased portal pressure, portal tributary blood flow and cardiac index. Changes in portal tributary blood flow, arterial pressure and cardiac index were significantly higher with vasopressin than with clonidine alone. Vasopressin infusion in rats pretreated with clonidine significantly increased arterial pressure and significantly decreased portal pressure, portal tributary blood flow and cardiac index. Changes in arterial and portal pressures and portal tributary blood flow were significantly higher with combined therapy than with clonidine alone. Changes in arterial and portal pressures and portal tributary blood flow did not differ between combined therapy and vasopressin alone. Changes in cardiac index were significantly higher with combined therapy than with clonidine or vasopressin alone. Hepatic artery blood flow was not affected by either clonidine or vasopressin but significantly declined with combined therapy. In conclusion, this study suggests that a combination of vasopressin and clonidine accentuates the portal hypotensive action of clonidine but not the action of vasopressin. Moreover, this study suggests that a combination of vasopressin and clonidine may have deleterious effects on systemic and hepatic artery vascular beds.

Animals↗
PubMed1994

[Relationships between plasma concentrations of endothelin and the severity of liver cirrhosis].

OBJECTIVES: Results of studies on plasma endothelin concentrations in patients with cirrhosis are conflicting. Moreover, the relationships between plasma endothelin concentrations and the severity of cirrhosis have not yet been studied. The aim of this study was to measure plasma endothelin concentrations in controls and in patients with cirrhosis. In addition, this study examined the relationships between plasma endothelin concentrations, and the severity of liver disease, splanchnic and systemic hemodynamics. METHODS: Plasma endothelin concentrations (in the hepatic vein and the right atria), hepatic venous pressures, arterial pressure, cardiac output, pulmonary pressures and plasma concentrations of sodium and creatinine were measured in 7 controls and 28 patients with cirrhosis. RESULTS: Plasma endothelin concentrations in the hepatic vein and the right atria were significantly higher in patients with cirrhosis (18.9 +/- 2.9 and 20.2 +/- 3.1 pg/mL, respectively) than in controls (6.1 +/- 1.1 and 7.2 +/- 1.1 pg/mL, respectively). In these patients, hepatic venous plasma endothelin concentrations were significantly correlated with Pugh's score (r = 0.49), hepatic venous pressure gradient (r = -0.44), and plasma sodium concentrations (r = -0.46). No significant correlation was found between plasma endothelin concentrations and systemic hemodynamics. CONCLUSION: Plasma endothelin concentrations are increased in patients with cirrhosis. Moreover, this increase is more marked in patients with severe liver disease than in patients with no or moderate impairment of liver function.

Blood Chemical Analysis↗
PubMed1993

Effects of intestinal insulin-like peptide on glucose catabolism in mealworm larval fat body in vitro: dependence on extracellular Ca2+ for its stimulatory action.

In vitro hormonally induced variations of glucose catabolism in mealworm fat body tissue were examined by a microradiorespirometric method. An insulin-like peptide (ILP) extracted from the midgut of last larval instar mealworm larvae significantly modified glucose catabolism and was dependent on energy metabolism and on the Ca2+ concentration in the culture medium. Using two different labelled substrate molecules, the stimulatory effects of ILP (compared with those of mammalian insulin) on the relative use of the pentose cycle as opposed to the glycolytic-citric acid cycle by the mealworm fat body were measured in vitro. Metabolic variations were evaluated using either [1-14C]glucose or [6-14C]glucose as substrates. Time course and dose-response curves of ILP and the hormonally induced variations in total CO2 and 14CO2 kinetics were determined. Modification in the specific radioactivity kinetics of 14CO2 derived from [1-14C] glucose and [6-14C]glucose molecules under hormonal effects were observed. As demonstrated in in vivo studies, ILP stimulated the relative utilization of the pentose cycle. However, this effect was observed much more rapidly, but for a shorter time, with fat body in vitro. Mammalian insulin produced similar, but not identical effects. Variations in transmembranous Ca2+ cellular exchanges, induced by either EGTA, nifedipine, or calcium ionophore ionomycin included in the culture medium, indicated that the stimulatory effects of ILP depends on this cation.

Animals↗
PubMed1993

Effects of terlipressin on hemodynamics and oxygen content in conscious portal vein stenosed and cirrhotic rats receiving propranolol.

Terlipressin is used in patients with variceal bleeding but its effects in patients receiving beta-adrenergic antagonists are unknown. In this study, the hemodynamic effects of terlipressin were evaluated in conscious portal hypertensive rats which had previously received a single dose of propranolol. Moreover, oxygen content and acid-base status were studied. In portal vein stenosed and cirrhotic rats, the addition of terlipressin (0.05 mg/kg) to propranolol (0.4 mg/kg) produced a decrease in portal pressure of 34% and 17%, respectively, and in portal tributary blood flow of 46% and 42%, respectively. In cirrhotic rats, however, the decrease in portal pressure was not significantly different when propranolol was combined with terlipressin than when propranolol was administered alone. Cardiac index also further decreased after terlipressin administration. In both groups of rats, these values were similar to those observed after terlipressin alone. In portal vein stenosed rats but not in cirrhotic rats, arterial pH was significantly lower following the combination of propranolol plus terlipressin than following saline, propranolol or terlipressin alone. In conclusion, terlipressin further reduces both portal pressure and cardiac index in rats with portal hypertension receiving beta-blockers. In portal vein stenosed rats but not in cirrhotic rats, the addition of terlipressin to propranolol induces acidemia. This study suggests that terlipressin might further reduce portal pressure in patients with portal hypertension treated with beta-blockers.

Animals↗
PubMed1993

Arterial and mixed venous acid-base status in patients with cirrhosis. Influence of liver failure.

Although it has been established that liver failure is associated with arterial hypocapnia and alkalaemia (i.e., respiratory alkalosis), the influence of liver failure on mixed venous acid-base status has not yet been studied. Thus, arterial and mixed venous acid-base status were simultaneously measured in controls and in a large series of patients with cirrhosis. Grade B patients (n = 28) or Grade C patients (n = 21) had significantly lower arterial and mixed venous carbon dioxide tensions than controls (n = 29). Grade B or Grade C patients also had significantly higher arterial, mixed venous pH, and lower mixed venous bicarbonate concentrations than controls. Among Grade A patients (n = 27), those with the lowest Pugh's score (i.e., equal to five) had significantly lower mixed venous carbon dioxide tension than controls. The other arterial and mixed venous acid-base values did not differ significantly between Grade A patients with the lowest Pugh's score and controls. Grade A patients with a Pugh's score equal to six and Grade B patients had similar acid-base disorders. No significant differences were found between groups concerning the anion gap and plasma chloride concentrations. In conclusion, this study shows that in Grade B or C patients, respiratory alkalosis was responsible for mixed venous hypocapnia, alkalaemia and hypobicarbonataemia. In addition, in Grade A patients with the lowest Pugh's score (equal to five), analysis of arterial and mixed venous blood revealed that mixed venous hypocapnia was the sole anomaly of the acid-base status. This last finding suggests that mixed venous hypocapnia might be an early event preceding the onset of arterial hypocapnia.

Alkalosis, Respiratory↗
PubMed1993

Renal hemodynamics in patients with cirrhosis: relationship with ascites and liver failure.

In patients with cirrhosis and ascites decreased renal blood flow might be related to the severity of liver disease but the relationship between the severity of cirrhosis and renal perfusion has not yet been established. Thus we measured renal, systemic and splanchnic hemodynamics in 63 patients with ascites and in 28 without ascites. When compared to patients without ascites, patients with ascites had lower renal blood flow (1,170 +/- 100 vs. 935 +/- 55 ml/min/1.73 m2; mean +/- SEM, p < 0.05) and renal perfusion pressure (78 +/- 2 vs. 72 +/- 1 mm Hg, p < 0.05 and higher inferior vena cava pressure (6.5 +/- 0.7 vs. 10.7 +/- 0.7 mm Hg, p < 0.05). Patients with ascites had significantly higher serum bilirubin concentrations, hepatic venous pressure gradient and lower serum albumin concentrations, indocyanine green (ICG) extraction than patients without ascites. Renal vascular resistance, glomerular filtration rate, mean arterial pressure, cardiac index and systemic vascular resistance were not significantly different between the two groups. By multiple regression analysis no significant correlation was found between liver tests (i.e., prothrombin time, serum bilirubin and albumin concentrations, ICG extraction), hepatic venous pressure gradient, cardiac index and systemic vascular resistance on the one hand and renal blood flow on the other. No significant correlation was found between glomerular filtration rate and liver tests. In conclusion, in patients with cirrhosis and ascites, renal hypoperfusion is not related to the severity of liver disease.

Ascites↗
PubMed1993

Molecular activation of a trehalase purified from the fat body of a coleopteran insect (Tenebrio molitor), by an endogenous insulin-like peptide.

Trehalase is the major factor involved in the release of glucose in the various insects organs. During physiological regulatory processes, and particularly during the induction or breaking of diapause, insulin-like factors are involved. Then, by contrast with the classical hypoglycemic role of insulin, the insulin-like peptide isolated from the insect (brain and/or fat body) is also able to activate the fat body trehalase in vitro, through a direct molecular interaction. The mechanism involves the binding of the activator to the "trehalase-trehalose complex", rather than on the free enzyme, without change in the Hill coefficient nor in the maximum velocity (Vmax). The rate constant KR is conversely proportional to the activator concentration. This mechanism can be totally quenched by adding an anti-serum anti-insulin-like factor in the reaction medium.

Animals↗
PubMed1993

Role of prostacyclin in hemodynamic alterations in conscious rats with extrahepatic or intrahepatic portal hypertension.

Although prostaglandins are thought to be involved in the hyperdynamic circulation of portal hypertension, the role of this substance has not been elucidated. Dose-response curves, the hemodynamic effects of prostacyclin (20 micrograms/kg) and its inhibitor indomethacin and measurements of plasma and urinary levels of 6-keto-prostaglandin F1 alpha were compared in three groups of six rats each: normal, with portal vein stenosis and with secondary biliary cirrhosis. Plasma and urinary levels of 6-keto-prostaglandin F1 alpha were higher in rats with portal vein stenosis and cirrhotic rats than in normal rats. Dose-response curves showed similar maximal decreases in arterial pressure in the three groups, whereas the maximal increase in portal pressure was less marked in cirrhotic rats than in normal rats and rats with portal vein stenosis. In normal rats, prostacyclin increased cardiac output by 21% and portal pressure by 41%. Similar increases were observed in rats with portal vein stenosis. In contrast, prostacyclin did not affect cardiac output and portal pressure in cirrhotic rats. Indomethacin induced a more marked vasoconstrictive effect in normal rats than in cirrhotic rats. This study shows that prostacyclin plays a role in the hemodynamic alterations in portal hypertension. Moreover, the hyporeactivity observed in cirrhotic rats suggests that prostacyclin plays a major role in the circulatory changes of portal hypertension due to chronic liver disease.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Persistence of systemic and splanchnic hyperkinetic circulation in liver transplant patients.

Portal pressure and portal-systemic collateral circulation after orthotopic liver transplantation have not been investigated. We studied systemic and splanchnic hemodynamics in 17 patients with cirrhosis before and 205 +/- 146 days after orthotopic liver transplantation. Among the 17 orthotopic liver transplantation patients, 12 had undergone hemodynamic study in the 6 mo before orthotopic liver transplantation. Controls were 50 patients with normal liver architecture. Cardiac index remained elevated in orthotopic liver transplantation patients compared with controls (3.6 +/- 0.9 vs 3.1 +/- 0.4 L/min.m2; p < 0.05). Azygos blood flow, which was elevated before orthotopic liver transplantation (585 +/- 402 ml/min), remained elevated after orthotopic liver transplantation (553 +/- 343 ml/min). In transplant patients, hepatic blood flow was higher than it was in controls (2.26 +/- 0.86 vs. 1.38 +/- 0.57 L/min; p < 0.05). Elevated hepatic blood flow correlated with cardiac index (r = 0.647, p < 0.025). In patients with normal graft function, hepatic venous pressure gradient was normal (2 +/- 1 mm Hg). In a patient with acute rejection, a sharp elevation in the hepatic venous pressure gradient was observed; it returned to normal 45 days after treatment. We conclude that despite normal portal pressure, portal-systemic collateral blood flow remains elevated after orthotopic liver transplantation. Possibly because of persistent collateral circulation, which may keep portal tributary blood flow elevated, hepatic blood flow is increased after orthotopic liver transplantation. Elevated splanchnic blood flow, in turn, contributes to the high cardiac index in liver recipients. Finally, a sharp elevation in portal pressure, which may be observed during acute rejection and subsides after treatment, merits further study.

Adult↗
PubMed1992

Plasma catecholamine concentrations are a reliable index of sympathetic vascular tone in patients with cirrhosis.

In patients with cirrhosis, the significance of elevated plasma catecholamine concentrations is unclear. Thus we investigated the relationship between plasma catecholamine concentrations and the hemodynamic effect of pindolol (an index of sympathetic vascular tone) in 10 patients with cirrhosis. Systemic and splanchnic hemodynamics and plasma catecholamine concentrations in the pulmonary artery and the splanchnic veins (hepatic and azygos veins) were studied before and after the oral administration of pindolol (20 mg). In basal conditions patients exhibited a hyperkinetic circulatory syndrome and elevated plasma catecholamine concentrations. Alterations in basal hemodynamics were correlated with plasma epinephrine concentrations but not with norepinephrine. Pindolol administration significantly decreased heart rate and increased right atrial pressure. After pindolol administration, individual hemodynamic changes (cardiac index, systemic vascular resistance, wedged hepatic venous pressure) were significantly correlated with plasma catecholamine concentrations. In conclusion, this study shows that in cirrhotic patients epinephrine may play a role in hemodynamic alterations, and plasma catecholamine concentrations are an index of sympathetic vascular tone.

Epinephrine↗
PubMed1992

Total effective vascular compliance in patients with cirrhosis: a study of the response to acute blood volume expansion.

Although arterial vasodilation is a well-known feature in patients with cirrhosis, the venous system remains unexplored. To measure total effective vascular compliance, a reflection of the properties of the venous system, rapid volume expansion (300 ml of a gelatin solution in 3 min) was performed in 23 patients. Eleven patients had compensated cirrhosis (Child-Pugh grade A or B), and eight had decompensated cirrhosis (Child-Pugh grade C). Four control patients had mild chronic hepatitis, normal hepatic venous pressure and normal liver architecture. Cardiac index, hepatic venous pressures, hepatic and azygos blood flow and renal plasma flow were measured before and immediately after volume expansion. Right atrial pressure was recorded during volume expansion. This allowed the calculation of total effective vascular compliance, which was higher in patients with decompensated cirrhosis than in those with compensated cirrhosis (4.65 +/- 4.21 vs. 1.34 +/- 0.63 ml.mm Hg-1.kg-1; p less than 0.05). In response to volume expansion, renal vascular resistance decreased significantly in patients with compensated cirrhosis, but not in those with decompensated cirrhosis (-30% +/- 33% vs. +2% +/- 23%; p less than 0.05). No change was seen in glomerular filtration rate. Systemic oxygen consumption increased in patients with compensated cirrhosis, but not in those patients with decompensated cirrhosis (25% +/- 33% vs. -4% +/- 9%; p less than 0.05). Although in all patients with cirrhosis volume expansion increased central venous pressures, azygos blood flow and the hepatic venous pressure gradient did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Evidence for normal nitric oxide-mediated vasodilator tone in conscious rats with cirrhosis.

Because it has been hypothesized that the hyperkinetic circulation in portal hypertension is the result of increased synthesis of nitric oxide, we compared the hemodynamic effects of nitric oxide synthesis--specific agonist (L-arginine) and antagonist between normal and cirrhotic conscious rats. The dose-response curves showed that L-arginine significantly decreased arterial pressure and increased heart rate. These changes started at the 200 mg/kg dose and were similar in both groups of rats. In both groups of rats NG-monomethyl-L-arginine (25 mg/kg) significantly decreased cardiac output by 35%. In cirrhotic rats, NG-monomethyl-L-arginine decreased portal pressure from 15.3 +/- 0.9 mm Hg to 13.6 +/- 0.7 mm Hg and portal tributary blood flow from 7.8 +/- 0.7 ml.min-1.100 gm-1 to 5.9 +/- 0.7 ml.min-1.100 gm-1; it significantly increased portal territory vascular resistance from 950 +/- 108 dyn.sec.cm-5.100 gm-1 x 10(3) to 1,579 +/- 258 dyn.sec.cm-5.100 gm-1 x 10(3). In normal rats, portal tributary blood flow decreased similarly, by 27%, and portal territory vascular resistance increased by 55%. In neither group was hepatic arterial blood flow altered. Before and after NG-monomethyl-L-arginine administration, arterial cyclic GMP concentrations were not significantly different between normal and cirrhotic rats. In conclusion, this study shows evidence of a normal role for nitric oxide-mediated vasodilatation in rats with cirrhosis and that inhibition of nitric oxide synthesis reduces portal hypertension. These results did not support the hypothesis that nitric oxide synthesis is increased in cirrhosis.

Animals↗
PubMed1992

Hemodynamic, neurohumoral, and metabolic responses to amino acid infusion in patients with cirrhosis.

In patients with cirrhosis the renal response to amino acid infusion is controversial. In addition, the renal and systemic metabolic effects of amino acids are unknown. Therefore, the present study examined the effects of amino acids on renal hemodynamics, renal and systemic oxygen (O2) consumption, and hormones in patients with cirrhosis. Twelve patients received an 8% amino acid solution for 30 minutes at a rate providing 250 mg of amino acids/kg body wt. Renal blood flow increased by 45% (P less than 0.05) and the glomerular filtration rate by only 9% (P greater than 0.05). Renal vascular resistance decreased by 23% (P less than 0.05), and renal perfusion pressure did not change significantly. Renal and systemic O2 consumption and pulmonary artery plasma glucagon level significantly increased. There were no significant changes in plasma osmolality, plasma volume, and plasma atrial natriuretic peptide concentrations. In conclusion, the results show that amino acid-induced renal vasodilation caused hyperperfusion but not renal hyperfiltration in patients with cirrhosis. In addition, renal hyperemia was associated with renal and systemic hypermetabolism.

Amino Acids↗
PubMed1992

Effects of theophylline on hemodynamics and tissue oxygenation in patients with cirrhosis.

Since adenosine may play a role in the hyperdynamic circulation of cirrhosis, we examined the effects of theophylline (an adenosine receptor antagonist) on systemic and splanchnic hemodynamics, tissue oxygenation and sympathoadrenal activity in patients with cirrhosis and liver failure. Theophylline (aminophylline) was administered intravenously for 30 min. Six patients received a dose of 3 mg/kg and eight others a dose of 6 mg/kg. The low dose caused plasma theophylline concentrations of 7.4 +/- 1.8 mg/ml (mean +/- S.E.), and induced a significant increase in heart rate from 84 +/- 5 to 93 +/- 8 beats/min. This dosage did not significantly change other hemodynamic values, oxygen (O2) consumption, or sympathoadrenal activity. The high dose elicited plasma theophylline concentrations of 15.8 +/- 4.0 mg/ml. This dose significantly increased heart rate from 78 +/- 5 to 87 +/- 7 beats/min and significantly decreased right atrial pressure from 2.5 +/- 1.0 to 1.4 +/- 0.8 mmHg, stroke volume from 52 +/- 3 to 47 +/- 5 ml.beat-1.m-2 and systolic arterial pressure from 140 +/- 5 to 129 +/- 6 mmHg. In contrast, O2 consumption, sympathoadrenal activity, and all other hemodynamic values (including azygos blood flow) were not significantly modified. As a result, we conclude that, in patients with cirrhosis, theophylline may cause decreased stroke volume which lowers systolic arterial pressure. In our patients theophylline also had a positive chronotropic effect but no vasoconstrictor effect on systemic and splanchnic circulation. Finally, theophylline did not improve tissue oxygenation in patients with cirrhosis.

Adult↗
PubMed1992

Hemodynamic and sympathetic responses to human atrial natriuretic peptide infusion in patients with cirrhosis.

To determine the potential usefulness of atrial natriuretic peptide (ANP) in patients with cirrhosis, we examined the effects of the infusion of a low dose of alpha-human ANP (alpha hANP, 25 ng.kg-1.min-1 for 30 min) on renal, splanchnic, systemic hemodynamics and sympathetic outflow in eight patients. Pulmonary arterial plasma ANP concentrations increased from 59 +/- 9 to 328 +/- 41 pg/ml (mean +/- S.E., p less than 0.05). Mean values of glomerular filtration rate and renal plasma flow were not significantly changed. Individual renal plasma flow responses differed from one patient to another. Renal plasma flow increased in two patients, decreased in three and did not change in the other patients. Renal plasma flow changes were correlated with basal renal plasma flow values (r = -0.938, p less than 0.05) but not with arterial pressure changes or renal vein plasma norepinephrine concentration changes. Azygos blood flow increased from 0.43 +/- 0.10 to 0.63 +/- 0.13 l/min (p less than 0.05) and the hepatic-venous pressure gradient decreased from 19.9 +/- 1.5 to 17.5 +/- 2.9 mmHg in post-infusion (p less than 0.05). Mean arterial pressure decreased significantly by 18% and cardiac output by 12%. Systemic vascular resistance and pulmonary arterial plasma norepinephrine concentrations were not significantly modified. Thus, in patients with cirrhosis, alpha hANP appears to have a direct vasodilating action on renal arterioles when basal renal vascular tone is high. In addition, although alpha hANP might exert a portal hypotensive action, alpha hANP induced arterial hypotension as a result of both low cardiac output and a lack of increased sympathetic vascular tone. The arterial hypotensive action may, thus, limit the therapeutic use of low doses of alpha hANP in cirrhotic patients.

Aldosterone↗