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G Melzi d'Eril

Publications and source records attributed to G Melzi d'Eril.

10 recordsLinked to original sources
PubMed1997

Biological variation in protein C, protein S and antithrombin concentrations in plasma of healthy subjects.

The analytical, intra- and inter-individual components of biological variation were estimated for protein C, protein S and antithrombin over a period of 6 weeks in a cohort of 17 apparently healthy subjects. Expressed as percentage activity (protein C and antithrombin) as a percentage concentration in normal human plasma (protein S), the mean values for men and women show no significant differences (p > 0.05) for any of the analytes studied. Calculated analytical goals (CV, %) for precision required for optimal patient care are: protein C, 2.9; protein S, 2.9 and antithrombin 2.7. A single numerical index, called "index of fiduciality", was also calculated to demonstrate that the analytical performance of our method was satisfactory. The generally applicable differences (% activity or % concentration) required for two results to be significantly different (p < or = 0.05) were calculated as: protein C, 17; protein S, 16 and antithrombin, 16. The usefulness of critical differences as guidelines for the interpretation of changes in serial results was investigated using an "index of heterogeneity" of intra-individual variation. The marked degree of individuality demonstrated for all the quantities indicates that, if conventional population-based ranges are used uncritically, major changes in analyte concentration may not be correctly identified for some patients, because observed values continue to lie within the reference range. The utility of conventional population-based reference intervals was determined by calculating a single numerical index, called "index of individuality". For protein C, protein S and antithrombin we found that five of a patient's specimens are required to achieve a 95% chance that the mean is within +/- 5% of the true value.

Adult↗
PubMed1996

Concentrations of L-dopa in plasma and plasma ultrafiltrates.

A sensitive and specific procedure is described for the determination of therapeutically relevant concentrations of L-dopa in plasma and plasma ultrafiltrates (free fraction) by high performance liquid chromatography with electrochemical detection. In plasma samples from healthy adult subjects (n = 15) spiked with L-dopa (500 micrograms l-1) the free fraction averaged 76 +/- = 8% (range 61-84%). Free fraction values increased by 38% with increasing plasma concentrations of L-dopa from 100-5000 micrograms 1-1. L-dopa free fraction was not affect by the presence of 3-O-methyl-dopa at concentrations up to 10,000 micrograms l-1.

Adult↗
PubMed1992

High plasma levels of catecholamines during insulin-induced hypoglycemic stress do not cause beta-adrenergic receptor sequestration.

In the present investigation insulin-induced hypoglycemia was used as a powerful stimulus to rapidly release epinephrine from the adrenal medulla. Insulin injection raised epinephrine 16-fold and doubled norepinephrine plasma levels. The aim of this attempt was to induce beta-adrenergic receptors (beta-ARs) sequestration in vivo on mononuclear leukocytes (MNLs). The number of total and surface beta-ARs was significantly increased 30 minutes after insulin administration, with only partial recovery at 90 minutes. No detectable receptor sequestration was observed: surface receptors were about 90% of total receptors in all the conditions examined. Isoproterenol-stimulated cyclic adenosine monophosphate (cAMP) accumulation was also increased after 30 minutes (+66%) and 90 minutes (+65%) of insulin injection. Basal and forskolin-stimulated intracellular cAMP values were unchanged. We conclude that, even after a strong release of catecholamines, beta-AR redistribution cannot be demonstrated on MNLs.

Adrenal Medulla↗
PubMed1992

Acute Guillain-Barré syndrome associated with asymptomatic HIV infection.

A 25-year-old male drug addict presented with a rapidly progressive ascending tetraplegia, requiring assisted ventilation. One month earlier he had fever (40 degrees C) and asthenia. Cerebrospinal fluid (CSF) examination showed elevated albumin level and albuminocytologic dissociation. HIV testing was positive in both serum and CSF. Plasma exchange therapy only partially improved the symptomatology. After five months the patient remained with a moderate tetraparesis. Differences between this and other cases of Guillain-Barré syndrome in HIV-seropositive patients reported in the literature are discussed.

Adult↗
PubMedDate not supplied

A rapid and simple method for determining catecholamines in human plasma and cerebrospinal fluid using high-performance liquid chromatography with electrochemical detection.

A procedure for assaying free norepinephrine, epinephrine, and dopamine in plasma and cerebrospinal fluid (CSF) is described. The method involves adsorption of the catechols onto alumina, desorption, and injection into a reverse-phase ion-pairing liquid chromatography system equipped with a coulometric detector. Optimization of chromatographic conditions with regard to detector performance and keeping to procedures and precautions described make the method applicable both to neurochemical research and routine clinical analysis. A single chromatographic run, providing adequate resolution of each component, could be completed in about 8 min. The limit of quantitative detection of the method was found to be approximately 0.003 micrograms/l for individual catecholamines.

Adult↗