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Biomedical subjects

R Valentini

Publications and source records attributed to R Valentini.

At least 19 recordsLinked to original sources
PubMed1999

High sensitivity simultaneous determination in hair of the major constituents of ecstasy (3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylene-dioxyethylamphetamine) by high-performance liquid chromatography with direct fluorescence detection.

A simple, but sensitive and specific high-performance liquid chromatographic assay for the simultaneous determination of the major constituents of "ecstasy" [i.e. 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyethylamphetamine (MDE)] with direct fluorimetric detection, particularly intended for the routine analysis of hair, is described. Hair samples (100 mg) were overnight incubated in 1 ml of 0.25 M HCl at 45 degrees C and extracted with a commercial liquid-liquid method. The dried residue reconstituted with 500 microl of 0.05 M NaH2PO4 pH 5.2 was injected. Isocratic reversed-phase liquid chromatography was carried out on a column (250x4.6 mm I.D.) packed with spherical 5-microm poly(styrene-divinylbenzene) particles; the mobile phase was composed of 0.1 M potassium phosphate (pH 3)-acetonitrile (82:18). The excitation and the emission wavelengths were set to 285 and 320 nm, respectively. Under the described conditions, MDA, MDMA and MDE eluted in symmetric peaks with an analysis time of 30 min. The limit of detection was lower than 1 ng/ml, with a signal-to-noise ratio of 5, for each compound in solution, allowing a cut-off of 0.1 ng/mg in the hair matrix to be established. The intra-day precision (n = 6) of the assay was characterised by RSDs between 1.0 and 3.0% and between 0.52 and 0.88% for concentrations of 10 and 100 ng/ml, respectively; in day-to-day precision tests (n = 6), RSDs ranged between 5.12 and 11.12%, respectively, for the same concentrations. Interferences from as many as 92 therapeutic and/or abused drugs currently in use in the population were excluded, including N-methyl-1-(3,4-methylenedioxyphenyl)-2 butanamine (MBDB).

Chromatography, High Pressure Liquid↗
PubMed1998

Determination of thyroxine in the hair of newborns by radioimmunoassay with high-performance liquid chromatographic confirmation.

Hair analysis is often used in forensic toxicology to study, retrospectively, chronic exposure of individuals to drugs, and consequently newborn hair may become an ideal sample to study intrauterine exposure to xenobiotics as well as to endogenous compounds. As a tool to investigate a supposed maternal thyroxine (T4) supply to the congenital hypothyroid fetus, we devised to use the analysis of T4 extracted from newborn hair. In the present paper, the analytical method based on T4 extraction from hair followed by a radioimmunoassay is described. To verify the nature of the T4-like immunoreactive material present in newborn hair, it was further studied by HPLC fractionation with radioimmunoassay of the eluted fractions. On the basis of a clear correspondence between retention times of T4 standard and T4-immunoreactive compound extracted from hair, we assigned this immunoreactive material to T4. Then, we determined T4 hair concentrations in 19 control newborns at birth and 12 congenital hypothyroid infants at 22 days of life. Values obtained from hypothyroid infants (31.47+/-8.8 pg/mg(hair), mean+/-S.D.) were not significantly lower than those obtained from healthy newborns at birth (36.10+/-13.2 pg/mg(hair)). Such results are in agreement with the hypothesis of a maternal supply of thyroxine to the fetus through placental crossing.

Chromatography, High Pressure Liquid↗
PubMed1997

Intracoronary angiotensin II potentiates coronary sympathetic vasoconstriction in humans.

BACKGROUND: In humans with coronary artery disease, ACE inhibition attenuates coronary sympathetic vasoconstriction. Whether this is due to removal of angiotensin (Ang) II production or to a reduced bradykinin breakdown, however, is unknown. METHODS AND RESULTS: In eight normotensive patients with angiographic evidence of mild left coronary artery lesions (< or = 50%), mean arterial pressure (MAP, intra-arterial catheter), heart rate (HR, ECG lead), coronary sinus blood flow (CBF, thermodilution method), and coronary vascular resistance (CVR, ratio between MAP and CBF) were measured before and during a 15-minute left intracoronary infusion of Ang II at a dose that had no direct coronary or systemic vasomotor effects. The same measurements were made before and during a 15-minute infusion of saline. A 2-minute cold pressor test (CPT) and a 45-second diving were performed at the end of either infusion period. These maneuvers were used because their coronary vasomotor effects are abolished by phentolamine and thus depend on sympathetic activation. During saline infusion, both CPT and diving caused a marked increase in MAP. HR increased with CPT and fell with diving. CBF increased in parallel to the MAP increase, with little change in CVR. The MAP and HR responses were similar during Ang II infusion, which, however, caused either no change or a reduction in CBF with a consequent marked increase in CVR with both CPT and diving. In four additional patients, the diameter of the stenotic vessels remained unchanged during the CPT performed under saline and Ang II infusion. CONCLUSIONS: Ang II markedly enhances sympathetic influences on coronary circulation in humans, presumably by acting at the arteriolar level. This may explain the blunting effect of ACE inhibition on sympathetic coronary vasoconstriction in patients with coronary artery disease.

Aged↗
PubMed1997

Growth hormone bioactivity and levels of growth hormone, growth hormone-binding protein, insulinlike growth factor I, and insulinlike growth factor-binding proteins in premature and full-term newborns during the first month of life.

OBJECTIVE: To assess the pattern of growth hormone bioactivity (GH-BIO) and the levels of GH-binding protein (GH-BP), insulin-like growth factor I (IGF-I), and insulin-like growth factor-binding proteins (IGFBPs) in the first month of life in premature and full-term (FT) newborns. PATIENTS AND METHODS: Serum samples were collected from 9 premature newborns who were small for gestational age, 18 premature newborns who were of appropriate size for gestational age, and 20 FT newborns on the 4th and 30th days of life to evaluate the GH-BIO using the Nb2 cell bioassay, the GH levels using a radio-immunoassay (GH-RIA), and the levels of GH-BP, IGF-I and IGFBPs. RESULTS: On day 4, the GH-RIA and GH-BIO values were increased in all newborns (P < .05) compared with values in the prepubertal control subjects. The GH-BP levels were low in all newborns, with the lowest values (P < .05) found in the premature newborns and positively correlated with gestational age (P < .001). The IGF-I levels were also low, with lower values (than those found in the FT newborns) (P < .005) found in the premature group and positively correlated with the GH-BP levels (P < .001) and gestational age (P < .001). The levels of IGFBP-1 and IGFBP-2 were high, with higher values found in the premature newborns than in the FT newborns (P < .05) and negatively correlated with gestational age (P < .005). The IGFBP-3 level was lower in the premature (P < .05) than in the FT newborns and positively correlated with gestational age (P < .005). During the first month of life, the GH-RIA and GH-BIO values were significantly decreased in all newborns (P < .001), while the IGF-I level was increased in the premature newborns (P < .005). The GH-BP levels were increased only in the FT newborns (P < .001). CONCLUSIONS: The elevated bioactive GH level seen in the first few days of life seemed to be attributable to a low IGF-I level secondary to a decreased number and/or function of the GH receptors. The decrease in the serum GH level observed thereafter seemed to be secondary to an increase in the IGF-I level in the premature newborns; however, other factors may have been involved in the FT newborns in whom no increase in the IGF-I level was observed.

Aging↗
PubMed1997

Growth hormone-binding proteins, IGF-I and IGF-binding proteins in children and adolescents with type 1 diabetes mellitus.

Growth hormone binding proteins, insulin-like growth factor I and insulin-like growth factor binding proteins were determined in 54 children and adolescents affected by type 1 diabetes mellitus (25 prepubertal and 29 pubertal) showing reduced height velocity and the results were compared to those of 104 matched controls. Growth hormone binding proteins were similar in prepubertal and pubertal subjects but were significantly lower in the prepubertal diabetic group than in controls. Insulin-like growth factor I was low both in prepubertal and pubertal diabetic subjects. Insulin-like growth factor binding protein 3 was similar to controls, while insulin-like growth factor binding protein 1 and 2 were always high in diabetic children. Insulin-like growth factor binding protein 4 was high only in the prepubertal diabetic group. In conclusion, a low insulin-like growth factor I in diabetic children seems to depend on a GH receptor and/or a postreceptor defect. A low insulin-like growth factor I together with a normal insulin-like growth factor binding protein 3 and high levels of insulin-like growth factor binding proteins 1, 2 and 4 results in a reduced bioavailability of insulin-like growth factor I to target tissues. This could be a possible contributing factor to the reduced height velocity seen in our diabetic children.

Adolescent↗
PubMed1997

Antigenic profiles for the differentiation of Mobiluncus curtisii and Mobiluncus mulieris by immunoblotting technique.

The antigenic profile of 30 vaginal isolates of Mobiluncus strains (22 M. curtisii and 8 M. mulieris) was determined by immunoblotting technique using mouse immune ascitic fluids containing polyclonal antibodies against the type strains M. curtisii subsp. holmesii (ATCC 35242) and M. mulieris (ATCC 35243). Two antigenic profiles were identified within M. curtisii isolates, whereas a certain variability was observed among M. mulieris strains where at least three antigens were constantly recognized. The detection of antigenic profiles of Mobiluncus strains by immunoblotting technique provided a simple method to identify Mobiluncus isolates at the species level.

Animals↗
PubMed1996

Postnatal variations of growth hormone bioactivity and of growth hormone-dependent factors.

OBJECTIVE: To evaluate whether the low insulinlike growth factor I (IGF-I) levels that are observed in the neonate depend on the biological inactivity of the molecular forms of growth hormone (GH) or on the immaturity of the hepatic GH receptors during the early postnatal period. MATERIALS AND METHODS: Serum samples were collected from 60 normal full-term neonates on day 5 and at 1 and 4 months of age to evaluate the GH concentrations by using both an immunofluorometric assay and Nb2 cell bioassay, as well as the GH-binding protein, IGF-I, and IGF-binding protein 3 values by radioimmunoassay. RESULTS: Five-day-old neonates showed significantly higher (P < .001) mean +/- SEM GH levels that were measured by using the immunofluorometric assay (27.22 +/- 1.62 micrograms/L) and Nb2 cell bioassay (3.56 +/- 0.14 U/mL) compared with those levels in 11 prepubertal children who were studied as control subjects (1.26 +/- 0.28 micrograms/L and 0.74 +/- 0.08 U/mL, respectively). At 1 and 4 months of age, GH values that were measured by using both the immunofluorometric assay (9.15 +/- 0.89 and 2.58 +/- 0.32 micrograms/L, respectively) and Nb2 cell bioassay (2.52 +/- 0.11 and 1.71 +/- 0.15 U/mL, respectively) were decreased significantly (P < .001). In 5-day-old neonates, we observed significantly lower (P < .001) serum GH-binding protein (9.73% +/- 0.42%), IGF-I (67.63 +/- 5.20 ng/mL), and IGF-binding protein 3 (1.46 +/- 0.17 mg/L) concentrations compared with those in the prepubertal children (30.74% +/- 2.01%, 210 +/- 25 ng/mL, and 3.08 +/- 0.22 mg/L, respectively). At 1 month of age, serum GH-binding protein (16.00% +/- 0.70%) and IGF-binding protein 3 (2.96 +/- 0.30 mg/L) values were increased significantly (P < .001), while IGF-I levels (72.55 +/- 7.6 ng/mL, P = .09) were not increased. Serum IGF-I values were increased significantly (P < .005) at 4 months of age (97.94 +/- 9.68 ng/mL). CONCLUSION: The interaction of bioactive molecular forms of GH with the increased hepatic GH receptors induces the rise in postnatal IGF-I levels in early infancy.

Age Factors↗
PubMed1996

Growth hormone treatment in osteogenesis imperfecta with quantitative defect of type I collagen synthesis.

OBJECTIVES: We studied growth rate, bone density, and bone metabolism in patients affected by type I osteogenesis imperfecta (OI) with quantitative defect in type I collagen synthesis during treatment with human growth hormone (hGH), being aware of its collagen-stimulating synthesis activity in vitro. STUDY DESIGN: Fourteen patients (6 boys; ages 4.8 to 10.8 years) were studied. Any structural alteration in the collagen chains was excluded, and reduced production of structurally normal type I collagen (increase in type III/type I collagen; reduction in the messenger ribonucleic acid alpha 1 (I)/ alpha 2 (I) ratio) was demonstrated. The patients were divided into two groups comparable in sex, age, height, and clinical severity of OI; seven patients (three boys) were treated for 12 months with hGH at a dosage of 0.2 mg/kg per week (0.6 IU/kg per week), in six injections subcutaneously, and seven were followed as control subjects. Auxologic data were measured every 3 months, and bone age was determined at the start, after 1 year of treatment, and 1 year after its completion. Every 3 months, serum insulin-like growth factor type I, osteocalcin, carboxyterminal propeptide of type I procollagen, alkaline phosphatase, calcium, and phosphorus levels and urinary hydroxyproline and calcium levels were determined. Bone mass measurements were carried out at the start of the study in all patients and repeated after 12 months in treated patients at the lumbar spine by dual-energy x-ray absorptiometry and by anteroposterior (second, third, and fourth lumbar vertebrae) and lateral (third lumbar vertebra) scan. Results were expressed as areal (anteroposterior and lateral) bone density (in milligrams per square centimeter) and as calculated true density (in milligrams per cubic centimeter). RESULTS: After 12 months, linear growth velocity in treated patients increased significantly in comparison with the pretreatment period (from 3.57 +/- 0.55 to 6.04 +/- 0.69 cm/yr; p < 0.05) and with the untreated group (p < 0.05). Bone age did not advance faster than chronologic age. The fracture index per year was low before treatment, and during therapy no patient had any fractures. Serum osteocalcin levels were statistically lower than in control subjects before treatment and increased significantly after 12 months (3.3 +/- 1.0 vs 2.1 +/- 0.9 nmol/L; p < 0.05). Serum levels of carboxyterminal propeptide of type I procollagen were significantly lower than normal values before treatment (164.6 +/- 46.7 vs 310.3 +/- 97.6 ng/ml; p < 0.05) and rose, but not significantly, during and after treatment. Before therapy, patients with OI had significantly lower lumbar anteroposterior, lateral, and calculated true bone density than the normal population of the same sex compared for both age and height. After hGH treatment, bone density increased significantly in the lumbar spine, in anteroposterior and lateral scans (+2.6 +/- 2.5% and +9.8% +/- 14.0%, respectively; p < 0.05). CONCLUSIONS: From our results, we conclude that hGH treatment in moderate OI does not increase the fracture risk in treated patients in the short term, significantly increases the rate of linear growth velocity, and increases bone turnover and mineral content in trabecular bone at the lumber spine.

Alkaline Phosphatase↗
PubMed1996

Growth hormone-binding proteins and insulin-like growth factor-binding proteins in protein-energy malnutrition, before and after nutritional rehabilitation.

To clarify the influence of nutrition on the GH-IGF axis in protein-energy malnutrition (PEM), we determined the serum levels of GH, GH-binding proteins (BP) (GHBPs), IGF-I, and IGFBPs in nine children with kwashiorkor and 13 with marasmus, before and after nutritional rehabilitation. In a basal condition, the GH level was significantly higher in the two malnourished groups than in controls (p < 0.01); in contrast, the second fraction of GHBP was lower and seemed to be related to the high GH and to a reduction in GH receptors. After refeeding, the GH level increased and the second fraction of GHBP decreased. The IGF-I basal level was higher in kwashiorkor than in marasmus subjects (p < 0.05), but in both groups it was significantly lower than in controls (p < 0.01); after refeeding it increased. IG-FBP-3, measured by RIA and Western blotting techniques, was in the control range in the kwashiorkor group but in the marasmic group it was significantly lower than in controls; after refeeding it decreased in kwashiorkor (p < 0.01 versus basal values) and increased in marasmus (p < 0.05 versus prerefeeding level). When sera of malnourished patients were mixed with adult control sera, incubated for 5 h at 37 degrees C, and assessed by ligand blotting, a low IGFBP-3 level in marasmus was found to be due to increased adaptive proteolysis of IGFBP-3; in contrast, in kwashiorkor the IGFBP-3 proteolytic activity was very low, probably because of inhibition by aflatoxins. These findings confirm that malnutrition affects the GH-IGF axis.

Adult↗
PubMed1995

Exercise standards.

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Echocardiography↗
PubMed1995

Bone mineral metabolism in girls with precocious puberty during gonadotrophin-releasing hormone agonist treatment.

Bone mineral metabolism and mineralization before and during treatment were studied in 10 girls aged 6.9-8.4 years affected by central precocious puberty and treated with gonadotrophin-releasing hormone agonist (GnRHa) leuprolide acetate depot, in order to understand better the consequences of oestrogen deficiency and the reduction of growth hormone (GH)-insulin-like growth factor I (IGF-I) axis activity. Before and after 12 months of therapy, the patients underwent a clonidine stimulation test and a 4-day calcitriol osteoblast stimulation test. On day 0, day 5 and at 3-month intervals thereafter, serum calcium, phosphate, alkaline phosphatase, IGF-I, IGF binding protein 3 (IGFBP-3), GH, GH binding protein and osteocalcin levels were measured; urinary calcium, phosphate and hydroxyproline levels were evaluated in fasting spot samples. Trabecular and cortical bone mass variations, measured by dual X-ray absorptiometry in the lumbar spine and by dual photon absorptiometry in the radius, respectively were evaluated before the start and after 12 months of therapy. During treatment, a decrease of serum oestradiol levels from pubertal to prepubertal levels was observed. The GH peak following clonidine diminished significantly after 1 year. Growth hormone binding protein showed a slight increase, and IGF-I and IGFBP-3 decreased, although not significantly. Osteocalcin levels decreased significantly after 9 and 12 months of treatment, but they did not change significantly after calcitriol load, either before or after GnRHa therapy. Urinary hydroxyproline decreased significantly after 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Height↗
PubMed1994

Free solution capillary electrophoresis of calcitonins and calcitonin tryptic digests.

The aim of the present work was the development of a simple capillary electrophoretic strategy, complementary to high-performance liquid chromatography, for the separation of different calcitonins (CTs) and calcitonin tryptic digests. Capillary electrophoresis was carried out with a manual capillary electropherograph with "on column" UV absorbance detection at 200 nm. The separation was accomplished in a 70 cm x 50 microns I.D. bare silica capillary. About 6 nl was loaded into the capillary by means of a split-flow system. Except in particular cases, electric fields of 300 V/cm were used at constant voltage. Separations were carried out in 0.05 M citrate buffer pH 2.5 or, alternatively, in 0.05 M borate buffer pH 9.5. A complete resolution of salmon, ASU1,7-eel, and human calcitonins was obtained in citrate and borate buffers. Other CT analogues could be separated only in one of the two buffers. Capillary electrophoresis in citrate buffer was also successful in the separation of the four final trypsin cleavage fragments of salmon calcitonin and, at least tentatively, of the nine intermediate cleavage products.

Analgesics↗
PubMed1994

Capillary zone electrophoresis determination of phenylalanine in serum: a rapid, inexpensive and simple method for the diagnosis of phenylketonuria.

A simple, rapid, and quantitative capillary zone electrophoresis method for phenylalanine analysis in serum has been developed, with the aim of providing an analytical tool, as an alternative to liquid and gas chromatography, for the routine laboratory diagnosis of phenylketonuria. Electrophoresis was carried out in a 65 cm long, 50 microns wide bare silica capillary, using 0.025 M borate (adjusted to pH 10 with 1 M NaOH) at a potential of 20 kV, with in-column UV detection at 214 nm. Under these conditions, the three aromatic amino acids (tryptophan, phenylalanine and tyrosine) migrated according to the pKs of the respective amine (and hydroxyl) groups. The efficiency of separation was about 150,000 plates/column for phenylalanine. Diprophylline was adopted as internal standard. The injection of ethanol-deproteinized normal control serum gave rise to only a few major peaks not interfering with phenylalanine; phenylalanine in serum at normal concentrations appeared in a clean region of the electropherogram as a symmetrical peak with a migration time of about 11 min. The sensitivity was > or = 3 micrograms/mL, with s/n ratio = 3. The linearity, in the range of 5-175 micrograms/mL, was described by the equation y = 1.407-0.583 x, r2 = 0.9998. Accuracy and precision were satisfactory, with intra-day and inter-day coefficients of variation lower than 4% and 7%, respectively. The injection of sera from five phenylketonuria patients gave electropherograms clearly showing huge peaks of phenylalanine, thus allowing an easy laboratory diagnosis of phenylketonuria.

Capillary Action↗
PubMed1990

[Early and late prognosis in acute myocardial infarct. A retrospective study in patients admitted to the coronary care unit in the past 10 years].

The prognostic evaluation of the patient with an acute myocardial infarction is one of the most interesting unanswered problems. This is both because of its complexity and its implications in terms of secondary prevention. Several clinical studies have emphasized the reliability of the prognostic evaluation based on data collected during the first 24 hours. We therefore evaluated the prognostic relevance of 26 variables measured in the coronary care unit in 1914 patients admitted to our Unit as a result of acute myocardial infarction during the past 10 years. Twenty-four patients were lost to follow-up so that the evaluation refers to 1,890 patients, 1,506 of whom are males aged between 22 and 99 years (mean 58.1) and 384 are females aged between 29 and 88 years (mean 67.1); thus there is a greater prevalence of males. The sex-related difference in the age distribution is statistically significant. In-hospital mortality was analyzed using univariate and multivariate statistical methods (chi-squared test, multiple logistic regression analysis). The prognostic relevance of the considered variables in relation to the survival was analysed using the logrank test and using Cox's model. The variables associated with a greater risk of in-hospital death were found to be: age, presence of diabetes, anterior location of the infarct, arterial hypotension at admission, Killip class III and IV and the presence of ventricular tachyarrhithmias. In contrast, smokers had a lower in-hospital death risk. As to mortality during the follow-up, there was an association with age, female sex, pre-existent coronary disease, presence of high heart rate on admission, low peripheral tissue perfusion, x-ray documented pulmonary congestion, supraventricular tachiarrhythmias and intraventricular block. In contrast, the presence of obesity was associated with a reduced death risk during the follow-up. During the follow-up the most frequent cause of death was re-infarction, followed by sudden death, death from non-cardiac causes and heart failure.

Adult↗
PubMed1987

Controlled study of the haemodynamic effects of isosorbide 5-mononitrate in acute myocardial infarction.

In view of the favourable results of the short-term therapy of acute myocardial infarction (AMI) with glyceryl-trinitrate (GTN) infusion, we undertook a randomized study to test the hypothesis whether the administration of a single dose of isosorbide 5-mononitrate (IS 5-MN) given orally would have the same favourable haemodynamic effect as observed with GTN infusion. For this purpose we evaluated the haemodynamic effects of IS 5-MN compared to isosorbide dinitrate (ISDN), observed in the same group of patients. 10 patients (8 males, 2 females) aged 50-76 years (mean 63) with AMI (7 anterior, 3 inferior) admitted to the coronary care unit within 48 h from onset of symptoms were entered into this single-blind randomized study; at the time of study entry, 8 patients were in Killip class I, and 2 patients in Killip class II. All drugs with haemodynamic effects were withdrawn 12 h before the study started. Both the haemodynamic profile and the clinical status were stable in all patients. Haemodynamic parameters were recorded with a Swan-Ganz thermodilution catheter, cardiac output was measured by the thermodilution method, and the left ventricular ejection time was calculated according to the Weissler method. The echo left ventricular end-diastolic diameter was measured by evaluation of the M-mode echocardiographic recording.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗