Determination of serum glucose concentration by a candidate definitive method.
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Blood Glucose↗
Biomedical subjects
F Magni
Publications and source records attributed to F Magni.
Determination of plasma glycerol isotopic enrichment by gas chromatography-mass spectrometry: an alternative glycerol derivative.
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Gas Chromatography-Mass Spectrometry↗
Insulin sensitivity and lipid levels in obese subjects after slimming diets with different complex and simple carbohydrate content.
The ideal hypocaloric diet should reduce body weight, decrease fat more than muscle tissue, and ameliorate insulin sensitivity and lipid levels. The aim of this study was to investigate the effect of three hypocaloric diets with different carbohydrate (CHO) and fat contents on body weight reduction, insulin release and sensitivity, and lipid levels in patients with simple obesity. Twenty-five obese subjects with normal glucose tolerance were randomly allocated to three hypocaloric (800 kcal) diets containing: 60% high complex/high starch and fibre (HC/HSF-CHO) and 20% fat (group 1;11 subjects); 60% high simple/high natural fibre (HS/HNF-CHO) and 20% fat (group 2; 7 subjects); or 20% CHO (L-CHO) and 60% fat (group 3; 7 subjects). The remaining 20% of the diet was protein. In all cases the duration of the diet was 21 days. Before and after the diet, seven subjects from each group underwent a hyperglycemic clamp, and the other four subjects of group 1 underwent a euglycemic-hyperinsulinemic clamp, combined with a glucose turnover study. A similar decrease in body weight, fat-free mass, fat mass, total cholesterol, LDL cholesterol and apo B levels was observed in the three groups. The M/I ratio during hyperglycemic and euglycemic-hyperinsulinemic clamp and the glucose turnover rate during euglycemic-hyperinsulinemic clamp significantly decreased, and FFA levels significantly increased only after the HC/HSF-CHO diet. HDL cholesterol and apo A1 significantly increased only during the HS/HNF-CHO diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Determination of plasma [6,6-2H2]glucose enrichment by a simple and accurate gas chromatographic-mass spectrometric method.
An improved method for the evaluation of glucose turnover rate in humans, using a prime-continuous infusion of [6,6-2H2]glucose, was developed. Deproteinization of plasma and conversion of glucose into the aldononitrile pentaacetate derivative are the only sample manipulations required prior to the gas chromatographic-mass spectrometric analysis. In six normal adults (prime = 5 mg kg-1; continuous infusion = 0.05 mg kg-1 min-1) the hepatic glucose output calculated at steady state by the procedure described here was 2.1 +/- 0.2 mg kg-1 min-1, the isotopic enrichment being determined with a coefficient of variation of ca. 2%. In six additional subjects, with half of the above-mentioned doses of labelled glucose, the mean hepatic glucose output was exactly the same (3.2% coefficient of variation for the isotopic enrichment measurement). The method described allows the hepatic glucose output to be precisely determined with savings both of time and of labelled glucose.
Blood Glucose↗
Defibrotide has antiischemic activity in perfused rabbit hearts, preventing tissue Ca++ overloading.
Defibrotide (D), a polydeoxyribonucleotide obtained from mammalian lungs, reduced the ischemic contracture due to low perfusion (0.2 ml/min) of the isovolumic left heart of the rabbit and abolished the irregularity of the rhythm of the heart, thereby restoring the cardiomechanical activity upon reperfusion (20 ml/min). D stimulated the release of PG-like material. Indomethacin infusion completely prevented both the antiischemic activity of D and its ability to increase the generation of prostaglandins in the rabbit heart. Measurement by atomic absorption spectroscopy of calcium content in ischemic heart tissue and its mitochondrial fraction indicated that the ischemic procedure significantly increased tissue calcium content in both. D, Prostacyclin (PGI2) and Nifedipine protected the heart from ischemic ventricular contracture and prevented accumulation of calcium in the heart. The effect of D on preventing Ca++ overload was completely abolished by indomethacin infusion. The results indicate that the beneficial effects of Defibrotide in experimental ischemia are primarily due to a release of Prostaglandin E2 (PGE2) and PGI2, which in turn may inhibit the detrimental effects of calcium overload in myocytes and mitochondria.
Animals↗
Diabetes-induced alteration of HMGCoA reductase forms in rat livers.
The effects of streptozotocin-induced diabetes on the various forms of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoA reductase), phosphorylated/dephosphorylated and thiolic/disulphide, were studied in rat liver. Animals were treated twice with 65 mg/kg intraperitoneally of streptozotocin to induce diabetes and sacrificed after 5 days. The relative amounts of the four possible forms of the enzyme were determined in control and diabetic rats. As determined from the total activity, and in agreement with previous reports, the enzyme protein was significantly decreased in streptozotocin-treated rats. However, the percentage of the active thiolic dephosphorylated form was higher in these animals than in controls, suggesting a response of the liver to the decrease both total and specific activity of HMGCoA reductase.
Animals↗
Determination of serum glucose by isotope dilution mass spectrometry: candidate definitive method.
We report a rather simple method to determine glucose concentration in serum, using isotope dilution mass spectrometry and [13C6]glucose as internal standard. The procedure involves a single step of sample purification and the conversion of the analyte into its aldononitrile pentaacetate. The between-day and within-day contribution to total variance for a single measurement was determined by assaying Standard Reference Material (SRM) 909 serum. The method was then applied to measurement of glucose concentration in three lyophilized sera: SRM 909 and two other commercially available sera. In the two studies, the concentration of SRM 909 serum was found to be 0.8% above and 0.3% below the reported value (6.25 mmol/L), respectively; the overall coefficient of variation for determinations in all sera ranged from 0.37% to 0.56%. The precision and the accuracy of the method satisfy the requirements for a Definitive Method.
Blood Glucose↗
Total urinary hydroxyproline determined with rapid and simple high-performance liquid chromatography.
A precolumn derivatization method was optimized for rapid and specific analysis of total urinary hydroxyproline by HPLC. After an overnight hydrolysis, urine samples dried and reconstituted with the internal standard cysteic acid (in sodium hydrogen carbonate, pH 9.3) were derivatized with N,N-diethyl-2,4-dinitro-5-fluoroaniline (FDNDEA) at 100 degrees C for 20 min. The DNDEA-hydroxyproline adduct was separated on an Ultrasphere ODS column with a mobile phase of acetate buffer (containing triethylamine, 6 mL/L, pH 4.3) and acetonitrile (80/20, by vol), and was detected at 360 nm. A single run took 18 min with a hydroxyproline retention time of 7.3 min. The assay showed a linear response to hydroxyproline concentrations from 5 to 100 mg/L with a detection limit of 0.8 ng injected, corresponding to 2 mg/L in urine. Mean (SD) analytical recovery was 94.2 (13)% and 104 (9)% at 10 and 50 mg/L, respectively. Within-run and between-run CVs (n = 10) were 3.74% and 4.33%, respectively, for 25 mg/L. Results for samples (n = 50) analyzed by HPLC (y) vs ion-exchange chromatography with postcolumn ninhydrin reaction (x) correlated well: y = 0.98x + 1.02 (r = 0.985, Sxy = 3.13). In another comparison, involving 173 samples, a colorimetric procedure (Hypronosticon, x) gave slightly higher values than the HPLC method (y): y = 0.83x + 2.21 (r = 0.937, Sxy = 4.6).
Aniline Compounds↗
[Plasma levels of mepivacaine in the double block of the sciatic and the femoral nerve].
The large use of double block of sciatic and femoral nerves (bibloc) with high mepivacaine 2% doses (10 mg/kg) has pointed out some cases of toxicity. We found a relationship between shiver and mepivacaine arterious plasma levels higher than 6 micrograms/ml. These symptoms were self-limited and statistically not significant.
Adult↗
Opposite effects of PGI2 and PAF generated during acute myocardial ischemia in the perfused rabbit heart.
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6-Ketoprostaglandin F1 alpha↗
Determination of platelet-activating factor in biological samples by high resolution mass spectrometry.
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Animals↗
Prevention of antigen-induced early obstructive reaction by inhaled furosemide in (atopic) subjects with asthma and (actively sensitized) guinea pigs.
The present study was undertaken to determine the effect of furosemide on antigen-induced bronchoconstriction. Ten patients with stable asthma (eight men and two women), aged 17 to 48 years, were challenged with the same dose of allergen (Dermatophagoides pteronissinus, Parietaria, and grass mix) that had induced an FEV1 fall of at least 20% in a preliminary study on two occasions: immediately after placebo and furosemide (approximately 28 mg) administered by inhalation in random order and double-blind. Furosemide did not demonstrate any direct bronchodilator effect but markedly attenuated allergen-induced bronchoconstriction. The mean (95% confidence interval) maximum fall in FEV1 was 31.5% (40.2% to 22.8%) after placebo and 8.4% (11.8% to 4.9%) after furosemide administration. Furosemide, administered by aerosol to anesthetized guinea pigs actively sensitized to ovalbumin, dose dependently protected the animals from anaphylactic reaction. Infusion of furosemide (10 mg/kg for 10 minutes) failed to protect the animals from the anaphylactic response. In nonsensitized guinea pigs, the cardiovascular and pulmonary changes induced by histamine (10 micrograms/kg intravenously [i.v.]), leukotriene C4 (1 micrograms/kg i.v.), and platelet-activating factor (0.1 microgram/kg i.v.) were not modified by aerosol administration of furosemide (10 mg/ml for 10 minutes). In conclusion, inhaled furosemide induces a clear-cut protection against immediate obstructive reaction caused by areoallergerns and ovalbumin, both in subjects with asthma and actively sensitized guinea pigs, respectively.
Administration, Inhalation↗
Production and biologic interactions of prostacyclin and platelet-activating factor in acute myocardial ischemia in the perfused rabbit heart.
This study showed that the 1-O-hexadecyl form of platelet-activating factor (PAF) is released along with 6-keto-prostacyclin1 alpha (6-keto-PGF1 alpha) in the perfusates of ischemic-isolated rabbit heart. During the early phase of the reperfusion, the release of PAF and 6-keto-PGF1 alpha was particularly increased (PAF, from 5.4 +/- 1.2 to 19.7 +/- 2.0 ng/min; 6-keto-PGF1 alpha, from 2.3 +/- 0.1 to 27.4 +/- 1.8 ng/min) and this event was coupled with the characteristic mechanical alterations of myocardial performance and perfusion pressure (PP). These changes were effectively antagonized by pretreatment of the hearts with both prostacyclin (PGI2, 20 ng/ml) and the PGI2-releaser defibrotide (400 micrograms/ml). The protecting activity observed with PGI2 was paralleled by a reduction in the rate of PAF release during reperfusion (from 19.7 +/- 2.0 to 6.8 +/- 0.2 ng/min). In defibrotide-treated preparations, inhibition of PAF formation was associated with a pronounced stimulation of 6-keto-PGF1 alpha generation, which was particularly marked on reperfusion (from 27.4 +/- 1.8 to 197.5 +/- 8.2 ng/min). Indomethacin (1 microgram/ml) ablated the antiischemic effect of defibrotide but did not potentiate the rate of formation of PAF despite inhibition of 6-keto-PGF1 alpha biosynthesis. From these results, we conclude that in a model of severe myocardial ischemia, in which the major determinants of cardiac performance are under control, generation of PAF and PGI2 appears to play an important biologic role in determination of the severity of myocardial ischemic damage.
Animals↗
LG 30435, a new potential antiasthmatic agent.
LG 30435 is a new quarternary phenothiazine derivative with H1-antihistaminic and antimuscarinic properties. The ability of LG 30435 to prevent changes in respiratory mechanics, induced by different mediators and the immunological reaction, was monitored together with biological and radioimmunological determination of circulating thromboxane-A2 (TxA2) in anaesthetized guinea-pigs. LG 30435 dose-dependently reduces the bronchoconstriction and TxA2 generation caused by different stimuli such as histamine, acetylcholine, leukotriene C4 (LTC4) and PAF-acether. In addition i.v. and aerosol administration of LG 30435 causes a dose-dependent reduction of the increase in airway resistance and TxA2 generation induced by ovalbumin challenge in actively sensitized animals. LG 30435 infused at different concentrations through the isolated guinea-pig lungs inhibits the TxB2 generation caused by different anaphylactic mediators, but not by arachidonic acid. These data, which further substantiate the bronchodilator activity of LG 30435 against a variety of stimuli and demonstrate its protective properties on lung anaphylaxis, suggest that this compound has a potential therapeutic value in the treatment of asthma.
Anaphylaxis↗
The PAF-acether receptor antagonist BN-52021 inhibits mediator release during guinea-pig active lung anaphylaxis.
An anaphylactic reaction was induced with the specific antigen (1 mg Ovalbumin) in perfused lungs from actively sensitized guinea-pigs in order to evaluate the ability of the ginkgolide BN-52021 (0.4, 4, 40 micrograms/ml) to modulate the mediator release. The ginkgolide reduces in a dose dependent manner the release of histamine (22%, 45% and 75% of inhibition), TXB2 (77% of inhibition at the maximal dose used) and of SRS-A to a lower extent (only 33% at the higher dose). BN-52021 was still powerful in reducing histamine release induced by immunological reaction in indomethacin treated animals. In conclusion, the present "in-vitro" results confirm the beneficial activity of this ginkgolide, already demonstrated by the same Authors in "in-vivo" experiment, in anaphylactic reactions, and further substantiate the wider spectrum of action of the ginkgolide beside its specific PAF receptor antagonistic activity.
Anaphylaxis↗
BN-52021 protects guinea-pig from heart anaphylaxis.
BN-52021 preserves "in vitro" the actively sensitized guinea-pig heart from the immunological reaction. This ginkgolide reduces mediator release (histamine, thromboxane-A2 and slow reacting substance of anaphylaxis) in a dose-dependent manner, particularly that of histamine. These results evidence either an important role for PAF in guinea pig anaphylaxis or a wider spectrum of activity for BN-52021.
Anaphylaxis↗
Nonsteroidal antiinflammatory drugs aggravate acute myocardial ischemia in the perfused rabbit heart: a role for prostacyclin.
Myocardial ischemia was induced in perfused paced isovolumic left heart preparation of the rabbit by reducing, for a period of 40 min, the flow rate from 20 ml/min to 0.2 ml/min (severe model) and to 1 ml/min (moderate model). The relationship between prostaglandin biosynthesis and cardiac ischemic damage was evaluated in the two experimental models. The results obtained indicate that the total amount of 6-keto-PGF1 alpha generated increases with the severity of the ischemia, particularly during the 20 min of reperfusion (moderate model 81.8 +/- 13.7 ng: severe model 375 +/- 102 ng). The inhibition of the prostaglandin synthesis, prostaglandin-E2, and 6-keto-prostaglandin-F1 alpha (PGE2 and 6-keto-PGF1 alpha levels below the detection limits) by Aspirin (20 micrograms/ml) and Indomethacin (1 microgram/ml) in moderate myocardial ischemia was correlated with greater increments in resting diastolic tension (nearly 100% and 40%, respectively). This phenomenon was also associated to a further decrease on cardiac contractility and increase on coronary perfusion pressure upon reperfusion. On the contrary drugs which stimulated prostaglandin generation in myocardial tissue, such as Defibrotide (400 micrograms/ml), completely protected the organ from ischemia. U-60257 (3 micrograms/ml) and FPL-55712 (2 micrograms/ml), compounds, which respectively inhibits biosynthesis and the effects of leukotrienes, displayed a beneficial activity on this moderate model of ischemia. The present data suggests that the deleterious effect of nonsteroidal antiinflammatory drugs in low flow myocardial ischemia and reperfusion damage may be associated with removal of PGI2 and PGE2 from ischemic myocardium.
Animals↗
New pharmacological data on the bronchospasmolytic activity of bamifylline.
Resistance to lung inflation and blood pressure were monitored together with biological and radioimmunological determination of circulating thromboxane A2 (TxA2) in anaesthetized guinea-pig. Bamifylline, a 2-benzyl-[4,5-d]-imidazopyrimidine derivative, and theophylline were compared for their antagonistic activity against the pulmonary effect of histamine (0.05 mumol/kg i.v.), leukotriene C4 (LTC4, 0.016 mumol/kg i.v.), platelet-activating factor (PAF, 0.0002 mumol/kg i.v.) and acetylcholine (0.1 mumol/kg i.v.). Bamifylline, as well as theophylline, showed a dose-dependent antagonistic activity against both bronchoconstriction and TxA2 generation induced by the above agonists. However, except for histamine where the two compounds were equiactive, bamifylline was 2 times more potent than theophylline. The maximal inhibitory activity was found against bronchoconstriction induced by PAF (ED50 = 6.5 mumol/kg i.v.) followed by histamine (ED50 = 9.5 mumol/kg i.v.), acetylcholine (ED50 = 24.3 mumol/kg i.v.) and LTC4 (ED50 = 31.6 mumol/kg i.v.). Bamifylline (3, 10, 30, 100 mumol/kg i.v.) and theophylline (3, 10, 30, 100 mumol/kg i.v.) protected guinea-pig from antigen-induced bronchoconstriction and TxA2 generation in ovalbumin actively sensitized animals. Also in this series of experiments bamifylline was more potent than theophylline, the ED50 being 9.3 mumol/kg i.v. and 22.9 mumol/kg i.v., respectively. These pharmacological data represent new support for the protecting effect of bamifylline against respiratory damage induced by well known anaphylaxis mediators.
Acetylcholine↗