Biomedical subjects
R Fumagalli
Publications and source records attributed to R Fumagalli.
[Familial hypercholesterolemia. Study of low-density lipoprotein receptors. Treatment with plasmapheresis].
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Lack of correlation between TPA-induced prostaglandin biosynthesis and ornithine decarboxylase activity in Balb/c mouse 3T3 fibroblasts.
12-O-tetradecanoylphorbol-13-acetate (TPA) induced in Balb/c 3T3 cells an earliest prostaglandin biosynthesis and an ornithine decarboxylase activation, this time-relation being more evident if serum was added to incubation medium in low concentration (0.2%). However the two TPA-induced events can be almost totally dissociated by pharmacological means, such as indomethacin and calcium-ionophore A23187 which affected PG response to TPA, but did not influence ODC induction.
Low-frequency positive-pressure ventilation with extracorporeal CO2 removal in severe acute respiratory failure.
Forty-three patients were entered in an uncontrolled study designed to evaluate extracorporeal membrane lung support in severe acute respiratory failure of parenchymal origin. Most of the metabolic carbon dioxide production was cleared through a low-flow venovenous bypass. To avoid lung injury from conventional mechanical ventilation, the lungs were kept "at rest" (three to five breaths per minute) at a low peak airway pressure of 35 to 45 cm H2O (3.4 to 4.4 kPa). The entry criteria were based on gas exchange under standard ventilatory conditions (expected mortality rate, greater than 90%). Lung function improved in thirty-one patients (72.8%), and 21 patients (48.8%) eventually survived. The mean time on bypass for the survivors was 5.4 +/- 3.5 days. Improvement in lung function, when present, always occurred within 48 hours. Blood loss averaged 1800 +/- 850 mL/d. No major technical accidents occurred in more than 8000 hours of perfusion. Extracorporeal carbon dioxide removal with low-frequency ventilation proved a safe technique, and we suggest it as a valuable tool and an alternative to treating severe acute respiratory failure by conventional means.
Morphological response to positive end expiratory pressure in acute respiratory failure. Computerized tomography study.
Ten patients with acute respiratory failure (ARF), (4 pneumonia, 4 sepsis, 2 polytrauma), underwent computerized tomography (CT) of the lungs, (apex, hilum, base), at 5, 10, 15 cm H2O positive end expiratory pressure (PEEP). The ARF lungs, on CT scan, appeared as a patchwork of normal and dense areas with generally well defined boundaries. Most of the densities were found in the dependent regions. The areas of density were correlated with PaO2 (r = 0.51). The PEEP increase resulted in a significant expansion of total cross-sectional lung surface area. The dense areas decreased significantly at the hilum and base when increasing PEEP while the changes at the apex were not significant. The changes of density with PEEP were highly correlated with the changes in oxygenation (r = 0.91). In the individual patient, however, the modifications of gas exchange can not be entirely predicted from morphological changes, possibly due to a diversion of pulmonary blood flow.
Selected ion monitoring technique for the evaluation of sterols in cerebrospinal fluid: a new approach to desmosterol test for central nervous system tumors.
The desmosterol test for the diagnosis of central nervous system (CNS) tumors is proposed in a simplified form. The procedure is based upon the analysis of sterol profile in cerebrospinal fluid (CSF) by selected ion monitoring (SIM) technique. Applied to 55 patients with tumoral and non tumoral CNS disease, the new test detects average levels of CSF desmosterol in tumor bearing patients that are tenfold higher than in the absence of CNS neoplasia. On an individual basis, a concentration of CSF desmosterol equal to or higher than the mean plus twice the standard deviation for the reference group of patients with no CNS tumor, is considered a positive result. Based on this criterion, a correct diagnosis was made in 73% of cases vs 77% of the former test, which required a 5-day treatment period with a desmosterol-reductase inhibitor in order to increase CSF desmosterol concentration. With this revised procedure CSF desmosterol can be detected in smaller volumes of CSF without any drug pretreatment, thus making the test more suitable for clinical application.
Calcium antagonists and low density lipoproteins metabolism by human fibroblasts and by human hepatoma cell line HEP G2.
The effect of Ca2+ antagonists (CA) on the receptor-mediated low density lipoprotein pathway has been investigated "in vitro" in human skin fibroblasts (HSF) and in human hepatoma cell line Hep G2. The specific binding and internalization of human 125I-labeled LDL are dose-dependently increased in HSF by CA of the verapamil series (verapamil, anipamil, gallopamil, ronipamil, and diltiazem), but neither by CA of the dihydropyridine series (nifedipine, nitrendipine) nor by flunarizine. BAY K 8644, a Ca2+ agonist, elicited an opposite effect. In the presence of the tested CA, LDL degradation is either unaffected (lower concentrations) or inhibited (higher concentrations). 125I-LDL uptake is stimulated also in fibroblasts from type IIa hypercholesterolemic patients, heterozygous for defective expression of LDL receptor. The enhanced cellular uptake of 125I-LDL was prevented by cycloheximide and by alpha-amanitin. CA of the verapamil series including diltiazem retained their effect in human hepatoma cell line Hep G2, a model proposed for hepatic metabolism of LDL. Our studies show that a) CA stimulate the high affinity binding and internalization of LDL in HSF and in human hepatoma cell line Hep G2; b) this stimulation involves DNA transcription and new protein synthesis; c) this effect is specific to one subgroup of Ca2+ antagonists (the verapamil class only).
Autoantibodies to the low density lipoprotein receptor in a subject affected by severe hypercholesterolemia.
We studied a 32-yr-old man with a benign paraproteinemia (IgA) affected by severe nonfamilial hypercholesterolemia. In vitro experiments demonstrated that lipoprotein-deficient serum (LPDS) from the patient inhibited the binding of low density lipoprotein (LDL) to human skin fibroblasts cultured in vitro (up to 70%) whereas LPDS from controls had no effect. Removal of IgA from the patient's serum by immunoprecipitation with mono-specific antisera abolished the inhibition of LDL binding. IgA isolated from the serum of the patient by affinity chromatography inhibited, in a dose-dependent manner, the binding of LDL to human skin fibroblasts in vitro, thus showing an IgA-mediated effect. Ligand-blotting experiments demonstrated that the paraprotein directly interacts with the LDL receptor, thus inhibiting the binding of the lipoprotein. Treatment of the receptor protein with reducing agents blocked the interaction of the antibody with the LDL receptor. From these data we speculate that this autoantibody may be responsible for the severe nonfamilial hypercholesterolemia of the patient.
Successful treatment of experimental neonatal respiratory failure using extracorporeal membrane lung assist.
A total of 44 preterm fetal lambs at great risk of developing respiratory failure were delivered by Cesarean section, and were then managed on conventional mechanical pulmonary ventilation. Fifteen animals initially fared well, and 14 of these were long term survivors. Twenty-nine other lambs showed a progressive deterioration in arterial blood gases within 30 minutes of delivery, of which 10 lambs were continued on mechanical pulmonary ventilation (20% survival), while the remaining 19 lambs were placed on an extracorporeal membrane lung respiratory assist (79% survival). Extracorporeal membrane lung bypass rapidly corrected arterial blood gas values, and permitted the use of high levels of CPAP instead of the continuation of mechanical pulmonary ventilation at high peak airway pressures. Improvement in lung function was gradual, and predictable. Early institution of extracorporeal respiratory assist using a membrane artificial lung rapidly corrected arterial blood gas values and significantly improved on neonate survival.
In vitro inhibition of rat arterial smooth muscle cell growth by extractive sulfated mucopolysaccharides.
The effect of a sulfated mucopolysaccharide mixture of known composition, extracted from pig duodenum, was studied on the proliferation of rat arterial smooth muscle cells cultured from rat aorta. Cell growth, stimulated by fetal calf serum, was monitored by direct cell count and by determination of the mitotic index. The extractive mixture was studied in comparison with commercial heparin, with heparin with different electrophoretic mobilities in barium acetate and with dermatan and heparan sulfates. Heparins and the extractive mucopolysaccharide mixture inhibited cell growth measured at various time intervals, and in their presence the proliferation of smooth muscle cells plateaued at lower cell densities. Dermatan and heparan sulfates were either inactive or significantly less effective than the other mucopolysaccharides. A short preincubation (3 h) of smooth muscle cells with the extractive mixture, followed by incubation with the growing medium with no mucopolysaccharides added, slowed the cell growing rate, suggesting an interaction of the mixture components with the cell surface.
Nonprotein sulfhydryls as possible components of the protective effect of rosaprostol on the rat gastric mucosa.
Experiments were designed to examine the possibility that nonprotein sulfhydryl groups of the gastric mucosa could participate in the protection of rat gastric mucosa by rosaprostol (the Na salt of 9-hydroxy-8,12 trans-19,20-bis-nor-prostanoic acid). Gastric mucosal lesions and the content of nonprotein sulfhydryls were evaluated after orally administered absolute ethanol. Pretreatment with rosaprostol by gavage prevented gastric lesions and reduced or prevented the decrease of mucosal nonprotein thiols. N-ethylmaleimide, a sulfhydryl blocker, worsened the ethanol-induced gastric lesions and lowered further the non protein thiols. Both variables were improved by the PG analogue and by PGE2. These results suggest a possible role of endogenous nonprotein sulfhydryl groups in the gastric protective effect of rosaprostol.
Differential effects of in vitro ethanol on prostaglandin E1-sensitive adenylate cyclase from smooth muscle cells and platelets.
In membranes of smooth muscle cells cultured from rabbit mesenteric artery, ethanol dose-dependently activates adenylate cyclase, both basal and PGE1- or GPP(NH)P-sensitive. The alcohol increases the maximal stimulation induced by PGE1 and GPP(NH)P, without greatly affecting their potency. The arrhenius plot displays a discontinuity point, which is only slightly lowered by ethanol. On the contrary, in membranes from human platelets ethanol inhibits basal, GPP(NH)P- and PGE1-sensitive adenylate cyclase, without modification of the prostaglandin or guanine nucleotide potency. The break point present in the Arrhenius plots is definitely lowered by the alcohol. In addition, ethanol decreases the thermostability of the enzyme. Neither in myocytes nor in platelets does ethanol affect the activation energy of the reaction. The data suggest that ethanol probably interacts directly with the membrane proteins, and that its effect is not mediated only through a perturbation of membrane lipid fluidity.
Prostacyclin-sensitive adenylate cyclase in cultured myocytes: differences between rabbit aorta and mesenteric artery.
Prostacyclin relaxes isolated strips of rabbit mesenteric artery and stimulates cholesteryl ester hydrolysis in rabbit aortic smooth muscle cells. Both effects are considered to be mediated by an increase in intracellular cAMP levels. Here we report that prostacyclin, prostaglandin E1 and two stable analogues of prostacyclin (5,6-dihydroprostacyclin and carbacyclin) dose dependently stimulate adenylate cyclase activity in membranes of cultured myocytes from both rabbit aorta and mesenteric artery. The rank order of potency in both systems was prostacyclin greater than carbacyclin greater than prostaglandin E1 greater than 5,6-dihydroprostacyclin, which parallels the order of potency observed for the vasodilator actions. Three other prostanoids, with limited vasoactive properties, prostaglandin D2, BW245C and 6-keto-prostaglandin F1 alpha failed to stimulate significantly adenylate cyclase activity. The two cell types differ in that the enzyme activation in aortic cell involves the interaction of each prostaglandin with one component of the adenylate cyclase system, while in mesenteric arterial cells the activation is brought about by the interaction with a higher and a lower affinity class of components.
[Markers of brain tumors].
Biological markers of tumors are compounds or enzymatic activities measurable in body fluids. Their presence or concentration must be linked to tumoral growth. The markers of the central nervous system tumors are detected in CSF. Alpha-feto-protein, carcinoembryonic antigen, human chorionic gonadotropin, adenohypophyseal peptide hormones, enzymes, etc., have found some application in the early diagnosis of leptomeningeal metastasis. Other applications involve the early detection and recurrency of primary brain tumors, as well as the evaluation of efficacy of their therapy. The tests based on the CSF content of desmosterol and polyamines have been studied extensively. Their rationale is discussed and specificity, sensitivity, efficiency and predictive value are considered. Experimental results concerning a new possible biochemical marker, based on CSF concentration of cyclic adenosine monophosphate, are reported.
Effects of probucol on the in vivo plasma clearance of human low density lipoproteins in rabbits and on the expression of lipoprotein receptors in vitro.
The purpose of this study was to investigate the effects of probucol on the plasma levels of low density lipoproteins in rabbits and whether the resulting decrease of low density lipoproteins was related to the effects of probucol on the expression of lipoprotein receptors. Probucol administration effectively lowered plasma cholesterol in normal rabbits. Both low density and high density lipoprotein cholesterol decreased, as well as apo B in the former fraction. Probucol had no effect on the fractional catabolic rate of low density lipoprotein while the flux of this lipoprotein decreased to about 50%. Moreover both the binding of lipoproteins to liver membranes and the in vitro uptake of low density lipoprotein by human skin fibroblasts were not affected by the drug. These findings are consistent with an effect of probucol on low density lipoprotein synthesis.
Prostacyclin-sensitive adenylate cyclase and prostacyclin binding sites in platelets and smooth muscle cells.
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Behavioural changes after acute and chronic administration of typical and atypical antidepressants in rats: interactions with reserpine.
Acute administration of desipramine, mianserin and viloxazine produces a significant decrease of locomotor activity in rats. Conversely, the locomotion of rats receiving the antidepressants for a prolonged period of time is not modified with respect to control animals. Moreover, the reserpine-induced decrement of locomotion is not influenced by chronic treatment with any of the antidepressants used in the present study. Since tolerance develops rapidly to these behavioural effects they may be indicative of compensatory changes in neuronal systems which may occur during prolonged antidepressant treatment.
Experimental studies on the hypolipidemic activity of chloridarol.
The efficacy of chloridarol (2-benzofuryl-p-chlorophenyl carbinol) as hypolipidemic agent was evaluated in rats and rabbits. In normolipidemic rats chloridarol, at doses ranging from 50 to 200 mg/kg/day, decreased plasma triglycerides without affecting cholesterolemia and fast- or norepinephrine-induced lipolysis. The drug proved effective in reducing fructose-induced hypertriglyceridemia and dietary hypercholesterolemia in rats; in the latter model chloridarol significantly raised both the HDL cholesterol and the HDL/VLDL + LDL cholesterol ratio. In hyperlipidemic rabbits the drug had no effect on plasma cholesterol, but it lowered triglyceridemia. The action of chloridarol on rat liver ultrastructure was also investigated. Treatment for one month induced peroxisome proliferation, less marked, however, than that elicited by clofibrate; after a prolonged chloridarol treatment (9 months), this effect had almost completely disappeared and the ultrastructure of the hepatocytes was close to that of controls.