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Biomedical subjects

A Ligabue

Publications and source records attributed to A Ligabue.

At least 37 records · Page 2Linked to original sources
PubMed1987

Polyamines stimulate superoxide production in human neutrophils activated by N-fMet-Leu-Phe but not by phorbol myristate acetate.

The polyamines putrescine, spermidine and spermine, at concentrations of 10 microM, stimulated superoxide generation by human polymorphonuclear leukocytes induced by fMet-Leu-Phe in the presence of Ca2+. This positive effect was not evident in the absence of Ca2+ or when the polymorphonuclear leukocytes were stimulated by phorbol myristate acetate. Spermidine in the range of 10-100 microM showed a dose-dependent stimulatory effect on the superoxide generation induced by fMet-Leu-Phe, whilst at doses above 25 mM it produced an inhibitory effect. At this concentration, spermidine did not reduce the phorbol myristate acetate-neutrophil-induced O2-. generation, while an inhibitory effect by the polyamine was evident at concentrations above 50 mM. In addition, 100 microM spermidine increased the amount of superoxide generated and enhanced the ability of the chemotactic peptide to stimulate superoxide generation. The polyamines in the range of 10 microM-25 mM did not modify the activity of purified NADPH oxidase, nor the rate of reduction of cytochrome c as supported by the xanthine/xanthine oxidase reaction. These results indicate that physiological concentrations of polyamines can stimulate superoxide formation by polymorphonuclear leukocyte cells produced by the chemotactic peptide fMet-Leu-Phe, probably by increasing the availability of external calcium.

Calcium↗
PubMed1987

Chronobiological evaluation of sympathoadrenergic function in cirrhosis. Relationship with arterial pressure and heart rate.

Intraday activity of the adrenergic system was investigated in 7 healthy controls and in cirrhotic patients without ascites (group 1, 7 cases) and with ascites (group 2, 9 cases) by determining the urinary norepinephrine and vanillylmandelic acid excretions at 4-h intervals for 24 h. Mean arterial pressure and heart rate were also recorded. In controls, the statistical evaluation by the cosinor method showed a circadian rhythm of such variables, with zenith in the morning and nadir at night. Intraday changes of urinary excretion of norepinephrine were closely related to arterial pressure and heart rate in most subjects. The most important change in cirrhotic patients was the achronia [no detection of a statistically significant (p greater than 0.05) rhythm] in urinary excretion of norepinephrine and arterial pressure. This occurred not only in group 2 patients, who had lower arterial pressure and higher NE mesors than controls (p less than 0.05), but also in group 1 patients, whose mesors were comparable to controls. The statistical significance of heart rate rhythmicity was preserved in patients, but its zenith was progressively displaced toward evening (group 1) and night hours (group 2, whose mesor was increased). Changes in urinary excretion of vanillylmandelic acid roughly paralleled those of norepinephrine both in controls and patients, but they did not significantly increase even in the group with ascites. In both groups of cirrhotic patients, the correlation between urinary excretion of norepinephrine, arterial pressure, and heart rate within the same subject was lost in most cases. This chronobiological study showed that the sympathoadrenergic activity can be deranged also in the early stages of cirrhosis, and suggested that an altered control of cardiovascular homeostasis is present even under steady state conditions. This alteration might blunt adrenergic responses to stress conditions.

Adrenergic Fibers↗
PubMed1985

Renal function impairment induced by change in posture in patients with cirrhosis and ascites.

The assumption of upright posture by patients with liver cirrhosis leads to striking activation of adrenergic and renin-angiotensin systems. The tilting-induced modifications in renal function of eight healthy controls and 14 untreated patients with liver cirrhosis and ascites were related to plasma concentrations of noradrenaline, renin activity and aldosterone. All patients had preserved renal blood perfusion. All parameters were evaluated during bed rest for two hours and in the sitting posture for one hour. Basal plasma renin activity (0.1 greater than p greater than 0.05), aldosterone and noradrenaline concentrations (p less than or equal to 0.01) were raised in cirrhotics. The renal function tests (creatinine clearance, filtered sodium, tubular rejection fraction, urinary sodium excretion) were significantly reduced in cirrhosis. Under basal conditions, in cirrhotic patients tubular rejection fraction and urinary sodium excretion were inversely related to both noradrenaline and aldosterone concentrations. After tilting, the noradrenaline and aldosterone integrated outputs (sigma delta) were significantly greater in cirrhosis. All renal function tests significantly decreased in cirrhotics, whereas creatinine clearance only significantly decreased in controls. Patient's tubular rejection fraction of sodium and sodium excretion were related to sigma delta aldosteronaemia (r = -0.72; p less than 0.01), but no longer to sigma delta plasma noradrenaline.

Adult↗
PubMed1984

Inhibitory activity of gallbladder bile on calcium carbonate crystallization in vitro. A comparison between normal subjects and gallstone patients.

The inhibitory activity of gallbladder bile on in vitro calcium carbonate crystallization was investigated in 12 normal subjects, 18 patients with radiolucent gallstones, and 18 patients with radiopaque or mixed gallstones, all of whom had functioning gallbladders. Inhibitory activity, expressed as CIT (crystallization inhibition time), was notably higher in the normal subjects and only slightly greater than the effect of water in the gallstone patients; the extrapolation of the results suggests that the difference in the method used to obtain the bile, by duodenal probe or during surgery, had little effect on the inhibitory activity. No significant correlation was found with the CSI (cholesterol saturation index) and the biliary lipid variables. In view of the frequent appearance of calcium carbonate in the composition of gallstones, the possibility is emphasized that the reduced inhibitory effect of bile in the crystallisation of CaCO3 plays a part in gallstone growth or formation.

Adult↗
PubMed1984

Catecholamine release in coronary sinus during vasospastic angina induced by ergonovine.

In seven patients with spontaneous angina and three control subjects, aortic and coronary sinus norepinephrine and epinephrine were assessed. Samples were taken in basal conditions and during ergonovine test in coronary sinus and aorta. The behaviour of some hemodynamic parameters as heart rate, blood pressure, left ventricular end diastolic pressure and coronary sinus flow was also studied. Resting myocardial norepinephrine and epinephrine flux was similar for both groups. In ischemic patients ergonovine induced a coronary spasm accompanied by an evident reduction of coronary sinus flow and a slight increase in arterial epinephrine and norepinephrine concentrations. However, a significant decrease in the net myocardial norepinephrine and epinephrine release was evidenced. After ergonovine, not significant changes in norepinephrine and epinephrine concentration and release resulted in control subjects. The increase in peripheral catecholamine concentrations found in ischemic patients during ergonovine test could represent a reflex activation of sympathetic activity induced by an ischemia dependent ventricular mechanical disfunction. The decrease in myocardial catecholamine release during angina could be justified by sequestration of epinephrine and norepinephrine in ischemic areas induced by vasospasm or reflex inhibition of cardiac sympathetic tone.

Adult↗
PubMed1982

Impairment of blood pressure control in patients with liver cirrhosis during tilting: study on adrenergic and renin-angiotensin systems.

Mean arterial pressure, phenylalanine, tyrosine, norepinephrine and plasma renin activity (PRA) were determined in the plasma of 6 healthy controls and 8 patients with liver cirrhosis receiving a controlled sodium intake (40 mEq/day), after 1 h of bed rest and 10 min after being tilted up at 90 degrees. After resting, patients showed lower arterial pressure (p less than 0.025) and higher plasma levels of phenylalanine (p less than 0.005), tyrosine (p less than 0.05), norepinephrine (n.s.) and PRA (n.s.) than controls. In spite of a prolonged and marked stimulation of the adrenergic system induced by tilting, arterial pressure of cirrhotics, after an initial increase, decreased significantly. A significant PRA increase was observed in both groups but in patients it was greater and lasted longer, up to 30 min, when PRA and arterial pressure were inversely and significantly correlated. The adrenergic system of cirrhosis then appeared unable to maintain adequate levels of arterial pressure, even though hyperstimulated. The renin-angiotensin system played an important compensatory role in this contest.

Adult↗
PubMed1981

[Catecholamine and renin-angiotensin system in blood pressure control in patients with liver cirrhosis].

The changes induced by active tilting in arterial pressure, plasma renin activity, norepinephrine and its precursors phenylalanine and tyrosine were evaluated in 8 patients with liver cirrhosis and 6 healthy controls. The results suggest the inability of the adrenergic system, though hyperstimulated, to maintain arterial pressure homeostasis in cirrhosis with a compensatory hyperactive renin-angiotensin system. Derangements in catecholamine synthesis, possibly due to altered utilisation of precursors to alternative final products (weak neurotransmitters?) can be taken into account.

Adult↗
PubMed1980

Neurovascular island flaps in the emergency reconstruction of the terminal phalanx of the thumb.

The technique of neurovascular island flaps is described applied as an emergency operation in six patients who presented with considerable loss of substance of the fleshy pulp of the thumb or total loss of the terminal phalanx. The writers consider that the reconstructive method described by them is an advance on the traditional method, since not only can the matter be resolved in a single operative session, but epicritic sensitivity is maintained, the length of the thumb remains unaltered, better aesthetic results are obtained, and there are no vasomotor or sympathetic disorders.

Adult↗
PubMed1979

Influence of urine on "in vitro" crystallization rate of calcium oxalate: determination of inhibitory activity by a [14C]oxalate technique.

A simple radiochemical method is proposed for the in vitro assay of the inhibitory activity of urine with respect to calcium oxalate crystal growth using [14C]oxalate as a tracer. The method shows an improved sensitivity over existing methods and indicates that citrate, pyrophosphate and chondroitin sulphate are active inhibitors of calcium oxalate crystal growth down to concentrations of 10(-5), 10(-7) and 10(-10) mol/l respectively. The inhibitory activity in the urines of 12 recurrent calcium stone-formers was significantly lower than in the urines of matched control subjects (P less than 0.01), confirming the clinical usefulness of the test.

Calcium Oxalate↗
PubMed1979

[Specific activity and release of norepinephrine in isolated and perfused rabbit hearts under various oxygen pressure].

The incorporation of 3H-tyrosine into norepinephrine of rabbit hearts perfused with Krebs-Henseleit solution containing 11 mM glucose and gassed with 95% O2 - 5% CO2 (control) or 80% O2 - 5% CO2 15% N2 (hypoxic) or 95% N2 - 5% CO2 (anoxic), was studied. In the control hearts a constant specific activity of norepinephrine without any release of catecholamine into coronary effluent was measured after 5, 15, 30, 60 minutes. The hypoxic perfusion while not causing any release of norepinephrine, produced a significant increase in tyrosine incorporation into norepinephrine. The specific activity of norepinephrine and its release into coronary effluent were increased by anoxic perfusion; this effect was most evident when the glucose was replaced with a solution containing 11 mM mannitol. These results suggest that the synthesis of norepinephrine in isolated hearts, lacking of sympathetic innervation, may be affected by different condition of oxygen supply.

Animals↗
PubMed1979

Assessment of cerulein effects on serum bile acids concentration in liver disease. Comparison with the test meal.

Twenty-four liver patients and seven healthy subjects underwent the enzymatic-fluorimetric assay of total serum bile acids during fasting and after a hyperlipidic meal, both alone and with the intramuscular administration of 0.3 microgram/kg of cerulein. A third test with cerulein alone was carried out on the control group and on 12 liver patients. The liver patients were divided into two groups; those with moderate and severe liver disease, according to the degree of liver function impairment and the clinical data. The best discriminant efficiency was observed in the test with the meal alone, even if, in the liver patients, the meal with cerulein caused a greater percentual increase of serum bile acids. After taking into account the most significant correlations between serum bile acids and liver function tests, the addition of cerulein to the meal may be recommended for liver patients with previous cholecystectomy or gallbladder pathology.

Adult↗
PubMed1978

Influence of ultrafiltration on plasma renin activity and adrenergic system.

The influence of efficient ultrafiltration without dialysis fluid was compared to the standard dialysis technique in two groups of 4 patients with chronic renal failure on maintenance haemodialysis. Supine plasma renin activity (PRA), plasma concentration of noradrenaline (NA), and adrenaline (A) and the Valsalva manoeuvre were determined before and after the period of ultrafiltration at the beginning and at the end of the experiment. The behaviour of these parameters was related to changes of blood pressure and body weight. The rapid weight loss was well tolerated during ultrafiltration only, with a significant increase of plasma catecholamines concentration; in contrast, patients treated with ultrafiltration and dialysis showed no significant increase of NA and A levels and they frequently became hypotensive. No relationship was observed between changes in PRA and those in body weight and blood pressure. Our data suggest that rapid removal of catecholamines during standard dialysis hinders the compensatory increase of the adrenergic activity and is responsible for hypotension.

Blood Pressure↗
PubMed1977

[Infrared spectroscopy in the quantitative determination of urinary calculi constituents (author's transl)].

Infrared spectroscopy of urinary calculi can be used for the quantitative determination of the major constituents in mixed stones; the method is simple and consists in area-measurements of specific absorption peaks of the spectrum of each compound. In the area-measurement method the average error is +/- 2,5% in calcium-oxalate-apatite and +/- 2% in ammonium magnesium phosphate-carboapatite mixtures; within these limits the calculus matrix do not affect significantly the value of areas. An investigation of 64 mixed renal stones shows that in 57% of the samples, apatite is present in the nucleus; uric acid and calcium-oxalate are the most frequent superficial compounds, while the external layer of ammonium magnesium phosphate and the mixture uric acid-calcium phosphate are rare events. In calcium-oxalate-apatite and ammonium magnesium phosphate-carboapatite calculi the quantitative composition of the nucleus and the external layer differ significantly. The proposed method of analysis of internal and external structures in renal calculi can be useful for the study of etiology, for the prevention and the treatment of urolithiasis.

Humans↗
PubMed1976

[Analysis of urinary calculi. Study methods].

A comparative study of the composition of a hundred urinary gravel stones is carried out, made by chemical analysis and spectroscopy infra-red. This research has shown that the spectroscopic method is better than chemical analysis: the latter method is excessively sensitive, above all when considering magnesium, phosphates and uric acid. The marked chemical disclosure of these substances takes us to false conclusions regarding the composition of the gravel stone with percentages varying between 20 and 40% of the cases. On the other hand chemical analysis has not revealed the presence of oxalates in 24% of the gravel stones examined. The spectroscopic method has shown itself to be simpler and faster to execute (a part from being more sensitive and precise), and capable of furnishing precise information on the composition of gravel stones, even very small ones of a weight of 500 microgram.

Chemistry Techniques, Analytical↗