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G Guidi

Publications and source records attributed to G Guidi.

At least 55 records · Page 3Linked to original sources
PubMed1998

Evaluation of the analytical performances of a new fully automated commercial immunonephelometric assay for lipoprotein(a).

Several commercial methods have been proposed for lipoprotein(a) (Lp(a)) measurements over the past decades. However, only a few of them appear completely suitable in terms of analytical performance, costs and practicability. We evaluated the analytical performance of a new commercial fully automated immunonephelometric assay for Lp(a) measurements on the IMMAGE Immunochemistry System. Mean within- and between-run coefficients of variation were 2.7% (range 1.2-4.7%) and 3.8% (range 1.8-7.9%), respectively. The linearity of the assay was confirmed up to 102 mg/dl and the deviation from the expected values did not exceed 4% (mean deviation: 1.9%). Moreover, the relative non-linearity was acceptable, ranging from 1.4% to 1.6% and hence constantly lower than the 2.5% upper limit. Since there is no reference method for Lp(a) measurements, 100 routine random serum samples measured by the IMMAGE Immunochemistry System immunonephelometric assay were further compared with two other commercial immunonephelometric assays (Array LPA immunonephelometric assay and BNA Latex-Enhanced Lp(a) nephelometric assay). Non-parametric regression and relative Spearman's correlation coefficients were satisfactory, (y=1.009x - 1.38; r=0.998 IMMAGE Immunochemistry System vs. Array LPA and y=0.922x - 0.40; r=0.989 IMMAGE Immunochemistry System vs. Behring Nephelometer Analyzer (BNA) Latex Lp(a) assay). On the basis of the results of the present evaluation we conclude that the analytical performance and the main technical features of the IMMAGE Immunochemistry System immunonephelometric assay make it a suitable method for Lp(a) measurement in clinical laboratories.

Automation↗
PubMed1998

Cystic fibrosis: when should high-resolution computed tomography of the chest Be obtained?

OBJECTIVE: To provide indications for high-resolution computed tomography (HRCT) of the chest in patients with cystic fibrosis (CF). DESIGN: We compared the HRCT and conventional chest radiography (CCR) scores and assessed their correlation with clinical scores and pulmonary function tests. SETTING: Department of Pediatrics, Federico II University, Naples, Italy. SUBJECTS: A total of 30 patients with CF 6.75 to 24 years of age. RESULTS: CCR scores correlated highly with HRCT (r = -0.8) and clinical (r = 0.5) scores, whereas total HRCT scores were not related to clinical scores. Of all the specific HRCT findings, only bronchiectasis appeared related significantly to the clinical score (r = 0.6). Most pulmonary function tests were related to CCR and total HRCT scores, but not to HRCT scoring of specific changes. Forced vital capacity and CCR scores appeared the best predictors of the HRCT score (multiple R = 0.58 and 0.79, respectively). In patients with mild lung disease, HRCT detected bronchiectasis and air trapping in 57% and 71% of the cases, respectively. In patients with more abnormal chest radiographs, bronchiectasis and air trapping were demonstrated on HRCT in all cases. CONCLUSIONS: These findings suggest that HRCT of the chest is most useful in the identification of early lung abnormalities in patients with CF with mild respiratory symptoms, whereas for established disease, CCR is still the first-line imaging technique. The advantage of detecting early changes on CT imaging awaits additional confirmation, at least until early therapeutic interventions affecting significantly the final outcome of the disease are demonstrated. In patients with advanced disease, HRCT may be useful in the evaluation of specific lung changes when more aggressive treatment such as chest surgical interventions is indicated. Given the cost of the procedure and the high radiation dosage compared with CCR, a careful assessment of the cost:benefit ratios of HRCT is strongly recommended in CF.

Adolescent↗
PubMed1998

[Three-dimensional imaging with computerized tomography. Etiologic considerations and methods for studying temporo-mandibular joints].

INTRODUCTION: The temporomandibular joint (TMJ) had always been studied with conventional tomography and, more recently, with Magnetic Resonance Imaging. Computed Tomography (CT) can demonstrate periarticular soft tissues only. Recently, the introduction of three-dimensional (3D) CT reconstructions with dedicated softwares permitted to demonstrate functional changes in the TMJ with a simple and accurate measurement system. MATERIAL AND METHODS: We examined 347 patients with TMJ disorders using two different 3rd generation CT units and acquiring two series of scans, with the mouth closed and in maximum opening. 3D reconstructions on predefined planes were obtained with a dedicated software and integrated with the electronic measurements of the following morphologic and functional parameters: zygomatic tubercle height, axis of sagittal inclination of the mandibular condyle, TMJ movement range and changes in torsion/dislocation of condylar angle. RESULTS AND DISCUSSION: CT showed the TMJ easily. This examination lasts about 10 minutes, plus 10-15 more minutes for 3D reconstructions. Some artifacts were found on 3D images--thresholding artifacts, defined as pseudoforamina and pseudocalcifications. Neverthless, 3D imaging can easily demonstrate an articular district which is very complex in both morphology and function, supporting or replacing similar subconscious processes made by radiologists themselves. This technique was well accepted by all our patients and functional results were always in agreement with clinical findings. Moreover, CT is the only technique showing both TMJ sides at the same time. Our measurement system was easy to perform, repeatable and comparable also thanks to its potentials of standardization on different CT units. CONCLUSIONS: CT with 3D reconstructions appears the gold standard technique for functional TMJ studies. Even though it provides no information on the joint disk--which MRI does--3D CT permits easy and accurate measurements of both TMJ sides which can support clinical findings.

Humans↗
PubMed1997

Spontaneous rupture of a hepatic angiomyolipoma: CT findings and literature review.

Angiomyolipoma is an uncommon lipomatous neoplasm of the liver, usually asymptomatic and identified incidentally. We describe the CT findings of a surgically confirmed case of spontaneously ruptured angiomyolipoma with evidence of internal hemorrhage and hemoperitoneum. The CT features were that of an exophitic, oval, well-defined mass with inhomogeneous attenuation values due to the presence of fat- and soft-tissue densities. A review of the literature identified 49 cases of hepatic angiomyolipoma. Few of these occurred in symptomatic patients and showed intratumoral hemorrhagic foci, but none had a clear rupture with external bleeding. To our knowledge, this is the first reported case with this complication.

Aged↗
PubMed1997

An FFT-based flow profiler for high-resolution in vivo investigations.

Pulsed Doppler spectral analysis is a well-established diagnostic technique in the assessment of arterial diseases. Because of hardware limitations, its use has been so far restricted to the analysis of a single sample volume located along the ultrasound beam axis. In this paper, we discuss the operation of a newly developed multigate instrument capable of performing, in real time, 64-point fast Fourier transforms of Doppler signals sampled from 64 different range cells. The new instrument is capable of accurately detecting the actual blood flow behavior in major human vessels. Significant examples of velocity profiles obtained in real time from carotid arteries in healthy subjects are reproduced here for the first time. Multigate extension of spectral analysis is demonstrated to be a suitable means for detailed in vivo investigation of blood flow dynamics.

Blood Flow Velocity↗
PubMed1997

Comparison of aminosidine (paromomycin) and sodium stibogluconate for treatment of canine leishmaniasis.

Twelve dogs naturally infected with Leishmania infantum were treated subcutaneously with aminosidine at a dose of 10 mg kg-1 per day for four weeks. Antimonial compounds were used as reference drugs in twelve Leishmania-infected dogs. Eleven of the twelve dogs submitted to aminosidine therapy responded within 30 days. The treatment with the aminoglycoside antibiotic presented a marked decrease of anti-Leishmania antibody titres than the controls. Aminosidine also reduced urinary protein, serum IgG, and circulating immune complex concentrations. Side effects were observed only in a dog with pre-existent renal lesions. This study proved that aminosidine is an effective, tolerable and safe drug for the treatment of canine leishmaniasis and that it could be used as a suitable substitute for antimonial therapy.

Amebicides↗
PubMed1997

Effects of nandrolone decanoate (Decadurabolin) on serum Lp(a), lipids and lipoproteins in women with postmenopausal osteoporosis.

Although lipoprotein(a) (Lp(a)) concentrations are mainly regulated genetically, it has been reported that variations in sex hormone concentrations may have effects on serum Lp(a). We evaluated the effect of nandrolone decanoate, a testosterone-derived synthetic anabolic steroid, on serum Lp(a), lipids and lipoproteins in 19 postmenopausal women who were given parenteral nandrolone decanoate (Decadurabolin) once a week for 3 weeks. At the 4th week, a significant decrease was observed for total cholesterol (p = 0.003), Lp(a) (p = 0.0003), apolipoprotein A-I (apo A-I) (p < 0.0001), and high density lipoprotein-cholesterol (HDL-C) (p < 0.0001). Moreover, a significant decrease in serum albumin concentration (p = 0.002) was concomitantly observed. We conclude that the administration of nandrolone decanoate significantly affects the lipid profile of postmenopausal women, showing controversial effects in terms of cardiovascular risk.

Anabolic Agents↗
PubMed1997

Clinical performance of leukocyte differential on the new Roche Cobas Vega haematological analyzer.

The Roche Cobas Vega is a five-part differential haematological analyzer evolving from the former Cobas Helios, Argos and Micros. As the leukocyte differential of Cobas Vega displays several interesting features, we analyzed its clinical performance and compared it either to three other commercial haematological analyzers (Technicon-Bayer H*2, Coulter STKS and Abbott CD-3500) or to the manual reference method, as described in the National Committee for Clinical Laboratory Standards (NCCLS) H20-A protocol. Within- and between-batch coefficients of variations (CVs) of the white blood cell differential were satisfactory and close, or even better than the ones reported for the other instruments: 0.81% (neutrophils), 1.87% (lymphocytes), 6.76% (monocytes), 7.73% (eosinophils) and 22.55% (basophils). The identification of abnormalities in the white blood cell differential was obtained either on the basis of the instrument-specific ranges or on the generation of one or more flags by comparison with results of the manual reference method. The Vega demonstrated remarkable performance in terms of specificity (90.0%), sensitivity (91.6%) and both positive (97.7%) and negative (69.1%) predictive values; likewise, the global efficiency was the best (90.3%) among the analyzers we evaluated. The flags generated in the presence of morphological abnormalities of the samples displayed excellent sensitivity (from 88.9% to 100%), specificity (from 93.5% to 98.3%) and satisfactory positive (from 51.1% to 66.7%) and negative (from 98.3% to 100%) predictive values. We conclude that the analytical performance of the new Cobas Vega haematological analyzer can significantly improve the identification of various haematological abnormalities as an important contribution to the accuracy is provided by the new staining for granulocytes.

Evaluation Studies as Topic↗
PubMed1997

In vitro effects of 50 Hz magnetic fields on oxidatively damaged rabbit red blood cells.

The aim of this study was to investigate the effects of 50 Hz magnetic fields (0.2-0.5 mT) on rabbit red blood cells (RBCs) that were exposed simultaneously to the action of an oxygen radical-generating system, Fe(II)/ascorbate. Previous data obtained in our laboratory showed at the exposure of rabbit erythrocytes or reticulocytes to Fe(II)/ascorbate hexokinase inactivation, whereas the other glycolytic enzymes do not show any decay. We also observed depletion of reduced glutathione (GSH) content with a concomitant intracellular and extracellular increase in oxidized glutathione (GSSG) and a decrease in energy charge. In this work we investigated whether 50 Hz magnetic fields could influence the intracellular impairments that occur when erythrocytes or reticulocytes are exposed to this oxidant system, namely, inactivation of hexokinase activity, GSH depletion, a change in energy charge, and hemoglobin oxidation. The results obtained indicate the a 0.5 mT magnetic field had no effect on intact RBCs, whereas it increased the damage with Fe(II)/ascorbate to a 0.5 mT magnetic field induced a significant further decay in hexokinase activity (about 20%) as well as a twofold increase in methemoglobin production compared with RBCs that were exposed to the oxidant system alone. Although further studies will be needed to determine the physiological implications of these data, the results reported in this study demonstrate that the effects of the magnetic fields investigated are able to potentiate the cellular damage induced in vitro by oxidizing agents.

Animals↗
PubMed1997

Evaluation of five new liquid stable applications on the Roche Cobas Integra.

In the present study the analytical performances of five new liquid applications on the Roche Cobas Integra were evaluated: urea and high density lipoprotein (HDL) cholesterol in serum and glucose, creatinine and inorganic phosphorus in urine. The analytical evaluation consisted of imprecision, linearity and method comparison performed against either the actual Cobas Integra granulate applications or the corresponding methods on a Hitachi 704, according to the National Committee for Clinical Laboratory Standards protocols. Over 3700 results were obtained within 3 months. Average values of within-run and between-day coefficients of variation (CVs) were 1.15% and 1.48%, respectively, holding to a mean total CV of 2.17%. The linearity was excellent for all the five applications evaluated as the relative non-linearity was always within 1.53%, thus completely fulfilling the 2.5% upper limit. A strict correlation was observed by comparing results of 120 samples with either the corresponding granulate applications on Cobas Integra or the Hitachi reagents. Linear regression analysis of the results yielded correlation coefficients always above 0.987 and the slopes of the Passing & Bablok regression lines did not deviate by more than 7% from unity. No drift was observed over 4 hours of operations. In conclusion, the performance of these new Cobas Integra liquid applications, as demonstrated by the present study, proved them to be highly suitable for routine use in clinical laboratories.

Chemistry, Clinical↗
PubMed1996

Significant reduction of the bias among commercial immunoassays for lipoprotein(a) after use of a uniform calibrator.

Despite the increasing interest in the measurements of lipoprotein(a) (Lp(a) in serum or plasma, at present there is no effective standardization for Lp(a) assays; the main problems to solve are represented either by the lack of a suitable primary standard or by the absence of a reliable and widely available reference method. A first step is hence the uniformity of calibration of different immunoassays. We calibrated three commercial immunoassays for Lp(a) (enzyme linked immunosorbent assay (ELISA), latex-enhanced immunonephelometric assay (LINA), and immunonephelometric assay (INA) with either proprietary standards or purified Lp(a) material obtained with a rapid and simple procedure. Final results of purified Lp(a) calibration were reported in terms of protein Lp(a) mass whereas we were able to quantify the exact protein concentration of our purified lipoprotein. The uniformity of the calibration of the different assays led to a significant improvement of regression slopes (from 1.88 to 0.90 ELISA vs. LINA, from 1.45 to 0.95 ELISA vs. INA and from 1.27 to 0.96 INA vs. LINA) and correlation coefficients (from 0.990 to 0.994 ELISA vs. LINA, from 0.987 to 0.990 ELISA vs. INA and from 0.985 to 0.987 INA vs. LINA). Furthermore, the significant differences among Lp(a) values obtained after calibration with proprietary standards were minimized, becoming non-significant in two out of three cases. In conclusion, we demonstrated that a better agreement of Lp(a) values obtained with different commercial assays could be simply reached by uniformity of calibration and by employing standards with values accurately measured.

Bias↗
PubMed1996

Simple and rapid procedure for the purification of lipoprotein(a).

Lipoprotein(a) [Lp(a)] is a low-density lipoprotein-like particle displaying strong athero-thrombotic properties. Highly purified Lp(a) is increasingly requested for standardization of Lp(a) measurements and for biological studies. Several procedures have been described for Lp(a) separation and purification but none of them appear completely suitable. We present here a procedure for Lp(a) purification based on sequential elutions after lysine-Sepharose affinity chromatography. We were able to identify four distinct subspecies of Lp(a) showing different affinity to epsilon-amino groups of lysine-Sepharose, simply by modifying molarity and pH of the eluents; the fraction obtained in highly purified state represented the major form and could be eluted with 0.5 M sodium phosphate buffer (pH 4.4). Advantages of this procedure are represented by simplicity, rapidity and final yield.

Chromatography, Affinity↗
PubMed1996

Serum paraoxonase activity is decreased in uremic patients.

Paraoxonase is a high-density lipoprotein (HDL)-associated enzyme capable of hydrolysing lipid peroxides. We measured the activity of serum paraoxonase together with serum concentrations of a variety of lipid constituents--total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), cholesterol, triglycerides, apolipoproteins A-I and B--in 60 hemodialyzed (HD) patients. We found that the paraoxonase activity was significantly reduced in HD patients compared with 64 healthy controls (mean median and interquartile values: 93, 63, 87 IU/l in HD patients and 151, 120 and 135 IU/l in controls). In patients, the trimodal frequency of distribution of paraoxonase activity showed a shift toward lower levels. The effect of NaCl on enzyme activation was more pronounced in the patient group, as compared with controls, suggesting a higher frequency of the B allozyme (more responsive to NaCl) in this population. We suggest that altered HDL subfraction, present in HD patients, may be the main cause of the widespread depression of paraoxonase. Furthermore, the higher frequency of allozyme B among HD patients might increase the risk of coronary artery disease. In conclusion, paraoxonase activity may be an adjunctive index of altered lipoprotein metabolism with important repercussions on atherosclerosis.

Adolescent↗
PubMed1996

Role of the parafascicular thalamic nucleus and N-methyl-D-aspartate transmission in the D1-dependent control of in vivo acetylcholine release in rat striatum.

We investigated the involvement of glutamatergic neurotransmission in the modulation of D1 receptor-mediated stimulation of acetylcholine outflow in dorsal striatum in freely moving rats, and the relative roles of the thalamostriatal and corticostriatal pathways in this regulation using in vivo microdialysis. The selective N-methyl-D-aspartate non-competitive antagonist dizocilpine maleate (0.1 mg/kg i.p.), but not the kainate/quisqualate receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione (3 micrograms per side i.c.v.), completely prevented the rise in striatal extracellular acetylcholine elicited by maximal effective doses of the full D1 agonist SKF 82958 (3 mg/kg s.c.) and of the dopamine releaser d-amphetamine (2 mg/kg s.c.). Acute bilateral electrolytic lesions of the parafascicular nucleus of the thalamus prevented the stimulation of striatal acetylcholine output by SKF 82958 and d-amphetamine but only slightly reduced basal acetylcholine release. In contrast acute interruption of the corticostriatal pathway did not alter the effect of the two dopaminergic drugs although it markedly reduced basal striatal acetylcholine release. Lesions of the parafascicular thalamic nucleus, or a low dose of dizocilpine maleate (0.1 mg/kg i.p.), also prevented the acetylcholine-increasing effect of the neuroleptic remoxipride (10 mg/kg s.c.), an effect known to be D1 receptor dependent. The results suggest that striatal projections arising from the parafascicular thalamic nucleus and utilizing N-methyl-D-aspartate receptors play a critical role in the D1-mediated stimulation of acetylcholine release in dorsal striata.

Acetylcholine↗
PubMed1996

Early detection of lung involvement in lysinuric protein intolerance: role of high-resolution computed tomography and radioisotopic methods.

Pulmonary disease of unknown etiology is a potentially fatal complication in patients with lysinuric protein intolerance (LPI), an autosomal recessive disorder caused by the defective transport of cationic amino acids. Lung involvement was investigated in nine Italian LPI patients through pulmonary function tests and lung imaging studies consisting of conventional chest radiography, high-resolution computed tomography (HRCT), and perfusion and ventilation scintigraphy. One 10-yr-old patient died of severe respiratory insufficiency from alveolar proteinosis. All of the remaining patients were asymptomatic at the time of the study, although HRCT scans revealed signs of lung involvement defined by the presence of acinar nodules, inter- and/or intralobular thickening of the interstitial septa, and subpleural cysts in five of the patients. Radioisotope studies showed an uneven distribution of perfusion and ventilation, and confirmed the presence of segmental and/or diffuse pulmonary functional defects. No abnormalities of pulmonary function were evident, and answers to a questionnaire excluded primary coexisting lung disease. In patients with LPI, including those without clinical and functional impairment, HRCT and radioisotopic studies appear to be the most sensitive methods for the early diagnosis of lung disease and correct assessment of its progression.

Adult↗