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Biomedical subjects

G Laffi

Publications and source records attributed to G Laffi.

108 records · Page 6Linked to original sources
PubMed1984

Vasoactive factors in decompensated cirrhosis. Effect of acute plasma expansion.

Plasma volume expansion was performed in 16 cirrhotic patients with ascites, 8 with avid sodium retention (sodium retainers) and 8 with normal sodium balance (sodium excretors). No natriuretic response was observed in sodium retainers (daily UNa = 7.1 +/- 1.5 mEq before expansion and 20.8 +/- 7.8 after expansion; p = not significant). After expansion plasma renin activity and plasma aldosterone showed a fall in both groups, whereas urinary kallikrein excretion decreased significantly in sodium retainers (27.1 +/- 9.7 before expansion and 7.8 +/- 6.4 after expansion; p less than 0.05). Baseline PGE were higher than normal in sodium retainers (997.0 +/- 134.3; p less than 0.02 vs. controls) and increased after expansion. Plasma octopamine was always within normal range. These results suggest that: a) reduction of effective plasma volume is not the main factor involved in sodium retention; b) the renin-angiotensin-aldosterone system has only a permissive role; c) prostaglandin system is activated and could have a protective role in maintaining renal function in cirrhotic patients.

Adult↗
PubMed1984

Vasoactive factors in the mechanism of renal sodium handling in cirrhotics: the effect of acute plasma expansion.

Twenty cirrhotic patients with ascites, divided into two groups of 10 each, according to their daily urinary sodium excretion (sodium retainers and sodium excretors) and given a diet of 75 mEq of sodium daily, underwent acute plasma volume expansion with 1,000 ml of 10% dextran in saline, infused through a catheter located in the right atrium. Even if a significant increase in sodium excretion was observed in both groups (p less than 0.001 in sodium excretors and p less than 0.05 in sodium retainers), plasma expansion did not reverse sodium retention in sodium retainers. A significant increase in creatinine clearance was found only in sodium retainers (p less than 0.02). Basal plasma renin activity and plasma aldosterone were elevated only in a few patients of both groups. The renin-angiotensin-aldosterone system was highly responsive to plasma expansion. Sodium retainers, who showed an ineffective natriuretic response after expansion, were able to suppress both plasma renin activity and plasma aldosterone in an analogous manner to the sodium-excreting group. This result lends strong support to the concept that the elevated aldosterone level in cirrhosis is not the major determinant of sodium retention. The kallikrein-kinin system was responsive to volume stimulus, since a decrease in kallikrein excretion was noted. It was significant in sodium retainers (p less than 0.05). Plasma PGE1,2 levels were significantly higher in sodium retainers than in controls. This may suggest that there is an activation of the intrarenal prostaglandin system, which could play a protective role against renal ischaemia. After volume expansion, PGE1,2 increased, but not significantly. Octopamine appeared unrelated to sodium excretion and unresponsive to volume stimulus. Endotoxins did not seem to be involved in renal sodium handling. Plasma volume expansion seemed effective in inducing a reduction of vasoconstrictor and sodium-retaining factors, such as the renin-angiotensin-aldosterone system. It is possible to suggest that volume expansion could increase PGE1,2. Plasma volume expansion produced different rates of sodium excretion in the two groups of patients and this suggests that impaired sodium handling in cirrhosis could, to some extent, be independent of effective plasma volume.

Female↗
PubMed1984

Expired hydrocarbons in patients with chronic liver disease.

Fifty patients with various types of liver disease and twenty-one healthy subjects were examined for lipoperoxidation in vivo by gaschromatographic assay of volatile hydrocarbons (ethane, ethylene, propane, n-butane, n-pentane) in breath gases. In 15 patients with alcoholic cirrhosis the amount of expired pentane was greater than in all the other groups examined. No significant increase of exhaled ethane, in contrast, was detected in the same patients. These results seem to indicate that pentane is a more sensitive index than ethane for ethanol-induced lipoperoxidation. This simple and non-invasive method opens up promising new opportunities for clarifying in humans, the role of lipoperoxidation in ethanol-induced liver damage, as well as in other chronic liver disease.

Adult↗
PubMed1983

Systemic hemodynamics and renal function in cirrhotic patients during plasma volume expansion.

Systemic hemodynamic impairment (hepatocirculatory failure) has been suggested as one of the possible factors which may explain the renal hemodynamic alterations found in the late stage of liver cirrhosis, typical of the hepatorenal syndrome. 20 patients, divided into two groups of 10 sodium retainers and 10 sodium excretors, affected by liver cirrhosis with portal hypertension and ascites, were studied. Renal functional parameters (diuresis, urinary and plasma electrolytes, urine to plasma osmolality and creatinine ratios and creatinine clearance) were evaluated before and after acute volume expansion with 1,000 ml of 10% dextran in saline, infused through a catheter located in the right atrium. Hemodynamic tests (cardiac index, systemic vascular resistance, right atrial pressure and capillary wedge pressure) were performed before, during and after expansion. Cardiac index decreased in 6 patients (sodium excretors) after a 500-ml infusion and rose again after 1,000 ml in 5 of them. The remaining 14 patients showed a progressive and significant increase of cardiac index. A strong inverse relationship between cardiac index and systemic vascular resistance was observed (r = -0.87; p less than 0.001). The mean left-ventricular function curve showed a slow response in most sodium excretors and a normal response in the sodium-retaining group, without significant difference between the two groups. Sodium excretion significantly improved after expansion in both groups of patients. No relationship was found between hemodynamic response and renal function. These data show that cardiocirculatory function is normal, even in sodium-retaining cirrhotics.

Adult↗
PubMed1980

Functional renal alterations in chronic liver diseases.

83 patients with chronic active hepatitis (CAH), 38 of them with cirrhosis, were studied and compared with 10 control subjects suffering from chronic persistent hepatitis (CPH). Tubular acidosis frequently was found in our cases. Renal plasma flow and glomerular filtration rate were significantly decreased in CAH when compared with CPH. Selective renal arteriography showed evident decrease of arterial flow in the outer cortex. Selective renal scan with 99mTc microspheres of human albumin showed a frequent escape of the tracer from the kidney to the lung. PGE1 and PGE2 levels appeared higher in the renal artery than in the vein and were significantly more elevated in 9 cases with cirrhosis vs. 13 controls. These results suggest the frequent functional impairment of the kidney also in the early stages of CAH, with an increase of PGE levels and an opening of intrarenal shunts.

Acidosis, Renal Tubular↗
PubMedDate not supplied

Altered platelet function in cirrhosis of the liver: impairment of inositol lipid and arachidonic acid metabolism in response to agonists.

Hemorrhagic disorders are common in patients with liver cirrhosis and result from several factors including impaired platelet function. We evaluated platelet aggregation and arachidonic acid metabolism in response to standard agonists in platelet-rich plasma from 12 cirrhotic patients with mild impairment of liver function (Child A), 12 patients with severe liver dysfunction (Child B and C) and 12 healthy subjects. Platelet aggregation and thromboxane A2 production were consistently reduced in patients with severe liver impairment. To determine whether the platelet dysfunction is due to an intrinsic platelet defect or a circulating inhibitor, we measured platelet aggregation and thromboxane A2 synthesis on washed platelets in healthy subjects and in Child B and C patients. The aggregating response of washed platelets in response to thrombin, collagen and arachidonic acid was markedly reduced, suggesting an intrinsic platelet defect. The biochemical events underlying platelet aggregation were investigated by prelabeling platelets with [1-14C]arachidonic acid. Thrombin-induced activation of phospholipase C (measured as the release of [1-14C]phosphatidic acid) and phospholipase A2 (measured as the release of [1-14C]arachidonic acid and its metabolites) was greatly impaired in platelets from patients with severe liver impairment. We conclude that in advanced cirrhosis there is a severe reduction in platelet aggregatory response to physiologic agonists due to an intrinsic platelet defect which is related to an impairment of the platelet transmembrane signaling mechanism induced by receptor stimulation.

Adenosine Diphosphate↗
PubMedDate not supplied

Changes in the production of nitric oxide and superoxide by inflammatory cells in liver cirrhosis.

Superoxide (O2-) and nitric oxide (NO) production by polymorphonuclear leukocyte (PMNs) and monocytes in patients with liver cirrhosis were evaluated. PMNs obtained from cirrhotic patients were less effective than those from controls in producing O2- after stimulation with opsonized zymosan, while they were more effective in producing NO, as shown by the inhibition of platelet aggregation and by the increase in cGMP content. NO synthase activity was higher in leukocytes from cirrhotic patients than in controls. A correlation was found between the cardiac index and the observed changes in the inflammatory cells.

Arginine↗
PubMedDate not supplied

Pathogenetic factors and clinical elements in ascites and hepatorenal syndrome during liver cirrhosis.

Ascites is the most frequent major complication of liver cirrhosis. Even if a significant decrease in renal clearances may be observed in the first stages of chronic active hepatitis, true renal impairment, often with the typical signs of hepatorenal syndrome, only occurs in patients with ascites, especially when tense and refractory. Experimental and clinical data suggest the presence of primary sodium and water retention, perhaps as a consequence of an increase in intrahepatic hydrostatic pressure. The abnormal sodium retention leads to plasma volume expansion, followed by decreased peripheral vascular resistances and increased cardiac output. This second stage concords with the peripheral arterial vasodilation theory, characterized by an increase in total blood volume, but with a decrease in effective arterial blood volume. This discrepancy leads to the activation of sympathetic nervous and renin-angiotensin-aldosterone systems. This activation, while protective against splanchnic and systemic vasodilation, provoked by the increased availability of nitric oxide and other vasodilating substances, induces renal vasoconstriction. This phenomenon can be considered as the basis of the progressive renal failure that leads to hepatorenal syndrome, favored by progressive exhaustion of the renal autacoid vasodilating substances. The first therapeutic approach to ascites is sequential and based on diuretic administration. Subsequently, paracentesis with albumin infusion is carried out, as well as transjugular intrahepatic portosystemic shunting, surgical portosystemic shunting, and liver transplantation: these procedures are essential for the treatment of hepatorenal syndrome.

Ascites↗
PubMedDate not supplied

Ascites in liver diseases.

The clinical course of patients with cirrhosis of the liver is frequently complicated by progressive impairment of renal sodium handling leading to the formation of ascites. The occurrence of ascites is generally accompanied by the activation of several hormones and intrarenal autacoids and a complex derangement of systemic, portal and renal hemodynamics. The earliest "underfilling" theory of sodium retention proposes that ascites formation leads to hypovolemia and secondary sodium retention. According to the "overflow" theory, ascites formation is a secondary event with respect to sodium retention, which occurs as a primary phenomenon in the absence of hypovolemia. A third recently developed theory suggests that peripheral arteriolar vasodilation is the primary event of intravascular underfilling. The major documented site involved in arteriolar vasodilation is the splanchnic circulation. Occurrence of underfilling is not related to a reduction of plasma volume but to the enlargement of the vascular compartment. Vascular underfilling triggers a series of hemodynamic and hormonal compensatory events such as an increase in cardiac output and plasma volume, activation of the renin-angiotensin-aldosterone and sympathetic nervous system and non-osmotic hypersecretion of antidiuretic hormone and sodium retention, all of which aim at refilling the vascular compartment. In patients with compensated cirrhosis, i.e. without ascites, compensatory events maintain blood volume despite vascular underfilling, and so these patients do not develop ascites. In patients with decompensated cirrhosis, vascular underfilling due to arterial vasodilation, together with a reduced oncotic pressure and a severe degree of portal hypertension, favours the development of ascites. Underfilling of the arterial circulation is at its maximum in functional renal failure and the hepatorenal syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascites↗
PubMedDate not supplied

Refractory ascites: definition, pathogenesis and treatment.

Refractory ascites, that is ascites which cannot be mobilized by low sodium diet and maximal doses of diuretics (up to 400 mg spironolactone or potassium canrenoate and 160 mg furosemide per day), occurs in 5% of cirrhotic patients with ascites. The development of refractory ascites is mainly related to the progression of arterial vasodilation-mediated vascular underfilling and to the imbalance between reduced synthesis of renal vasodilating factors (especially renal prostaglandins) and extreme activation of vasoconstricting systems. Further features include increased sodium reabsorption in the proximal tubule and altered pharmacokinetics and pharmacodynamics of diuretics. In patients with impaired renal function (as is the case for most patients with refractory ascites), the marked reduction of renal perfusion and glomerular filtration rate, with the consequent decrease of filtered sodium load, becomes the main pathogenetic factor. The principal therapeutic options for refractory ascites include repeated paracentesis and implantation of the LeVeen shunt. Paracentesis is a rapid and safe procedure to remove ascites, but it does not correct sodium retention. Ascites recurrence, therefore, may occur after a brief interval. The LeVeen shunt allows for better long-term control of ascites, but severe complications may supervene, and shunt occlusion is common. Neither therapeutic procedure improves survival. Different experimental therapeutic procedures have been proposed. Administration of ornipressin corrects hyperdynamic circulation and improves renal function. Thromboxane synthase inhibitors, by reducing renal synthesis of thromboxane A2, potentiate the diuretic and natriuretic response to furosemide. More invasive procedures, including portosystemic shunt and transjugular intrahepatic stent, are rarely used in the treatment of refractory ascites.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascites↗