Biomedical subjects

A Rosi

Publications and source records attributed to A Rosi.

At least 19 recordsLinked to original sources

PubMed2006

Optical images of dose distributions in Gel-Fricke: dosimetric performances of the gel.

The purpose of this work was to examine the dosimetric performances of the radiochromic Fricke-Agarose-Xylenol Orange gel by optical measurements in order to perform dose reconstructions, in view of a future development for 3-D maps. Optical images and dose-response curves of the gel were obtained by a CCD-based device, originally designed for reading radiochromic films, that was modified to meet the optical properties of the dosemeter. With a resolution of 0.18 x 0.18 mm the optimum range of doses in which per cent uncertainty is lower than 2% was 3-10 Gy. The minimum detectable dose, estimated as the absorbed dose corresponding to 3 SD above background, was 0.1 Gy. With a resolution of 1.98 x 1.98 mm the optimum range of doses in which per cent uncertainty is lower than 2% was 0.3-10 Gy. The minimum detectable dose, estimated as the absorbed dose corresponding to 3 SD above background, was 0.015 Gy. The comparison with alanine dosemeters in the dose range 7-10 Gy showed agreement within a few per cent and the same agreement was observed for the comparison with TLD in the range 1-3 Gy.

Dose-Response Relationship, Radiation↗

PubMed2006

Radiation effects in cultured tumour cells examined by 1H MRS: mobile lipids modulation and proliferative arrest.

Much attention has been devoted in the past to monitor changes of mobile lipid (ML) (1)H MRS signals in spectra of tumour cells. The purpose of this work is to exploit ML signals to provide information on cell metabolism after irradiation, comparing tumour cells characterised by different radiosensitivity and relating MRS findings to changes in cell proliferation and delays in cell cycle phases. Irradiated HeLa cells present less intense ML signals with respect to controls. The opposite is true for MCF-7 cells. A G(2) arrest is observed for both cell lines after irradiation. In HeLa cells, G(1) decreases and S phase is maintained; a sub G(1) peak is also visible. In MCF-7 cells, G(1) is decreased and S phase is strongly reduced, while no sub G(1) is present. The observed changes in ML are tentatively associated to cell cycle regulation of phospholipid synthesis. Mathematical modelling of ML variations is in progress.

Cell Cycle↗

PubMed2006

Optical imaging of dose distributions in Fricke gels.

Ferrous-sulphate infused gels, or 'Fricke gels', encounter great interest in the field of radiation dosimetry, due to their potential for 3D radiation dose mapping. Typically, magnetic resonance (MR) relaxation rates are determined in these systems in order to derive the absorbed dose. However, when large concentration gradients are present, diffusion effects before and during the MR imaging may not be negligible. In these cases, optical techniques may represent a viable alternative. This paper describes research aimed at measuring 3D dose distributions in a Fricke-xylenol orange gel by measuring optical density with a CCD camera. This method is inexpensive and fast. A series of early experiments is described, in which optical density profiles were measured with a commercial microdensitometer for film dosimetry. The light box of the device was modified to work at 567 nm, close to the maximum absorbance of the ferric ion-xylenol orange complex. Under these conditions, the gel shows linearity with dose and high sensitivity.

Dose-Response Relationship, Radiation↗

PubMed2005

Multidisciplinary and multisetting team management programme in heart failure patients affects hospitalisation and costing.

BACKGROUND: We evaluated whether multidisciplinary disease management programme developed with collaboration of physicians and nurses inside and outside general district hospital settings can affect clinical outcomes in heart failure population over a 12-month period. METHODS: 571 patients hospitalised with CHF were referred to our unit and 509 patients agreed to participation. The intervention team included physicians and nurses from Internal Medicine and Cardiac Dept., and the patient's general practitioners. Contacts were on a pre-specified schedule, included a computerised programme of hospital visits and phone calls; in case of NYHA functional class III and IV patients, home visits were also planned. RESULTS: The median age of patients was 77.7+/-9 years (43.3% women). At baseline the percentage of patients with NYHA class III and IV was 56.0% vs. 26.0% after 12 months (P<0.05). Programme enrolment reduced total hospital admissions (82 vs. 190, -56%, P<0.05), number of patients hospitalised (62 vs. 146, 57%, P<0.05). All NYHA functional class benefited (class I=75%, class IV=67%), with reduction in the costing (-48%, P<0.05). Improvement in symptoms (-9.0+/-3.2) and signs (-5.2+/-3.1) scores was measured (P<0.01). Therapy optimisation was obtained by 20.5% increase in patients taking betablockade and 21.0% increase in those on anti-aldosterone drugs. CONCLUSIONS: Multidisciplinary approach to CHF management can improve clinical management, reducing hospitalisation rate and costing.

Aged↗

PubMed2003

Novel antitenascin antibody with increased tumour localisation for Pretargeted Antibody-Guided RadioImmunoTherapy (PAGRIT).

The Pretargeted Antibody-Guided RadioImmunoTherapy (PAGRIT) method is based on intravenous, sequential administration of a biotinylated antibody, avidin/streptavidin and (90)Y-labelled biotin. The hybridoma clone producing the monoclonal antitenascin antibody BC4, previously used for clinical applications, was found not suitable for further development because of the production of an additional, nonfunctional light chain. In order to solve this problem, the new cST2146 hybridoma clone was generated. The monoclonal antibody ST2146, produced by this hybridoma, having the same specificity as BC4 but lacking the nonfunctional light chain, was characterised. ST2146 was found able to bind human tenascin at an epitope strictly related, if not identical, to the antigenic epitope of BC4. It showed, compared to BC4, higher affinity and immunoreactivity and similar selectivity by immunohistochemistry. Biodistribution studies of biotinylated ST2146 and three other monoclonal antitenascin antibodies showed for ST2146 the highest and more specific tumour localisation in HT29-grafted nude mice. On the overall, ST2146 appears to be a good alternative to BC4 for further clinical development of PAGRIT.

Animals↗

PubMed2003

MRS study of the interaction of dihydropyridines with lipid molecules in phosphatidylcholine vesicles.

Dihydropyridines (DHPs), synthetic molecules used as antihypertensive agents, bind to plasma membrane receptors following diffusion through the hydrophobic phase. In this study, MRS technique has been used to clarify the interactions of the dihydrophyridines Nifedipine and Lacidipine within the lipid bilayer. 1D and 2D 1H MRS at high field have been employed to examine the behavior of unilamellar dimyristoyl-phosphatidylcholine liposomes when the two drugs have been inserted in the bilayer. In particular, the study represents an innovative application of 2D 1H NOESY technique to clarify different mechanisms of interactions of small molecules inside model membranes. On the other hand, 31P measurements have been performed in multilamellar dimyristoyl-phosphatidylcholine lipsomes to detect alterations of lipid polymorphic phases. The experiments show that the two dihydropyridines interact with the lipids by different modalities. Lacidipine undergoes a very strong interaction with lipids, possibly inducing a phase segregation of lipid molecules into the bilayer, while self-association seems to be the prevalent interaction of Nifedipine inside the bilayer.

Dihydropyridines↗

PubMed2002

Changes in soluble metabolites induced in tumour cells by gamma rays and proton beams: a 1H magnetic resonance spectroscopy study.

Cultured HeLa cells have been irradiated with a single acute dose of either gamma rays (40 Gy) or low energy proton beams (20 Gy). 1H magnetic resonance spectra of perchloric acid extracts (PCA) prepared at different times after irradiation show an intensity decrease of signal from glutathione and a parallel increase of lactate signal. Intensity ratios of signals of glycerophosphorylcholine to that of phosphorylcholine increase with time after irradiation. Irradiating cells with gamma rays or proton beams at half a dose obtain effects of comparable extent. The present experiments indicate that relevant metabolic alterations take place in cells damaged by irradiation. Finally, these data represent a first indication that the relative biological efficiency of low energy proton beams with respect to gamma rays can reach a value of 2 as evidenced by cell metabolic impairment.

Dose-Response Relationship, Radiation↗

PubMed2001

Radiation effects on soluble metabolites in cultured HeLa cells examined by 1H MRS: changes in concentration of glutathione and of lipid catabolites induced by gamma rays and proton beams.

Cultured HeLa cells were irradiated with a single acute dose of either gamma rays (40 Gy) or low-energy proton beams (20 Gy). (1)H magnetic resonance spectra of intact cells harvested at different times after irradiation and of the correspondent perchloric acid (PCA) extracts prepared at different times after irradiation were run. Selected signals from glutathione and lactate were examined with the aim of investigating effects of irradiation on antioxidative stores and on mitochondrial activity. An increase of signal intensity of glutathione (GSH) takes place at 15 and 24 hr after irradiation, while a decrease of its signal intensity, accompanied by an increase of that of free glutamate, starts appearing 48 hr after irradiation. Lactate signal increases 48 hr after irradiation. Signals from lipid catabolites were also examined to explore their sensitivity in predicting the response to radiotherapy. Intensity ratios of signals of glycerophosphorylcholine and choline to that of phosphorylcholine increase with time after irradiation. Irradiating cells with gamma rays or proton beams at half a dose produces effects comparable to the metabolic variations presented here. The present experiments allow more insight into the complex pattern of the changes of GSH by irradiation and indicate that magnetic resonance spectroscopy signals from GSH, glutamate, lactate, and lipid catabolites are affected by irradiation. Finally, these data represent a first indication that the relative biological efficiency for some metabolic damage of low-energy proton beams with respect to gamma rays can reach a value of 2.

Flow Cytometry↗

PubMed2001

Changes in cell volume and internal sodium concentration in HeLa cells during exponential growth and following lonidamine treatment.

Cell volumes decreased in HeLa cells as a function of time after seeding during exponential growth. Cell volume distributions revealed the presence of two cell populations in all stages of growth. When cells approached confluence, the ratio of the two populations abruptly shifted towards that characterised by the smallest volume. Percentages of G1-, S- and G2 + M-phase cells were also measured and it was found that G1 frequency increased as a function of cell density during exponential growth. Intracellular sodium concentration, [Na]i was monitored by 23Na NMR in the presence of 5 mM dysprosium (III) tripolyphosphate. [Na]i increased from 22.8 to 59.0 mM in cells from the second to the seventh day after seeding. Treatment with lonidamine, an antitumoral drug that it is known to slow down cell growth by affecting aerobic glycolysis, produced a complete block of cell progression after a few days of treatment. The progression of cell volume distributions towards smaller volumes and the increase in internal sodium concentration as a function of time after seeding were also affected by the drug. These phenomena were related to the existence of a subpopulation of mitotically inactive G1-phase cells during exponential growth, pointing out that a density-dependent cellular mechanism regulates the cell cycling in HeLa cells.

Antineoplastic Agents↗

PubMed2000

Oral amiodarone increases the efficacy of direct-current cardioversion in restoration of sinus rhythm in patients with chronic atrial fibrillation.

AIMS: Direct current cardioversion of persistent atrial fibrillation is one of the most widely used and effective treatments for the restoration of sinus rhythm, but may be hampered by a low success rate and a high percentage of early recurrence. Pre-treatment with amiodarone or a glucose-insulin-potassium solution could improve the efficacy of electrical cardioversion by reversing the partially depolarized diastolic potential of the subsidiary pacemakers in atrial fibrillation. In a controlled randomized study, we assessed the effectiveness of electrical cardioversion in patients with persistent atrial fibrillation after pre-treatment with amiodarone or potassium infusion and the efficacy of amiodarone in maintaining sinus rhythm after electrical cardioversion. METHODS AND RESULTS: Ninety-two patients with persistent atrial fibrillation (>2 weeks duration) were prospectively randomized into three matched groups: A (n=31, oral amiodarone 400 mg. day(-1)1 month before and 200 mg. day(-1)2 months after cardioversion), B (n=31, 180 mg. day(-1)oral diltiazem 1 month before and 2 months after cardioversion and 80 mmol potassium, 50 UI insulin in 500 ml 30% glucose solution 24 h before cardioversion) and C (n=30, control patients, 180 mg. day(-1)oral diltiazem 1 month before and 2 months after cardioversion). Before cardioversion all patients were under 4 weeks effective oral anticoagulant therapy (warfarin). Before electrical cardioversion, the rate of spontaneous conversion to sinus rhythm was higher in group A (25%) than groups B (6%) or C (3%) (P<0.005). Electrical cardioversion was more successful in group A (88%) than groups B (56%) or C (65%) (P<0.05), while the electrical thresholds for effective cardioversion were lower in group B than the other groups (P<0.05). Twenty-four hours after cardioversion, the early recurrence of atrial fibrillation was similar in the three groups (P=ns), while at 2 months the recurrence rate was lower in group A (32%) than groups B (56%) or C (52%) (P<0.01). CONCLUSION: Pre-treatment with low-dose oral amiodarone, compared with oral diltiazem or glucose-insulin-potassium treatments, induces a significantly high percentage of instances of spontaneous conversion, increases electrical cardioversion efficacy and reduces atrial fibrillation recurrence.

Adult↗

PubMed2000

MOMO syndrome: a possible third case.

This report describes a 5-year-old girl, mildly mentally retarded, with the following characteristics: macrocephaly; severe obesity; ocular abnormalities (right optic disk coloboma and left choroidal coloboma); short stature; and recurvation of the femur. The case is sporadic with no consanguinity between the parents. The condition was diagnosed tentatively as MOMO syndrome (Macrosomia, Obesity, Macrocephaly, and Ocular Abnormalities) (MIM, 157980), because of the presence of short stature, in contrast with the large stature of the only two previously described cases. It is the third possible example of this rare syndrome to be described in the literature, with some new clinical findings presented.

Abnormalities, Multiple↗

PubMed2000

[Changes in the cardiac rhythm in ischemic cardiopathy].

Ventricular arrhythmia associated with ischemic heart disease has an important role in the etiology of sudden death, both in acute and chronic coronary syndromes. The etiopathogenesis of ventricular arrhythmia is strictly linked to the time-course from the occurrence of coronary occlusion. In the very acute phase of the ischemia, ventricular arrhythmias are due to a reentry mechanism, while 4-8 hours after occlusion the enhanced automatism, and triggered activity are the key mechanisms. Therefore reentry mechanisms are the main factors responsible for postinfarction arrhythmias. Also autonomic mechanisms, electrolytes and pharmacological therapy may contribute to cause arrhythmias.

Arrhythmias, Cardiac↗

PubMed1999

1H-MRS lipid signal modulation and morphological and ultrastructural changes related to tumor cell proliferation.

Changes in signal intensity of (1)H-MRS mobile lipids, mostly triglycerides, have been observed in cultured HeLa cells during exponential growth. Signals were intense in the first days after seeding and almost disappeared after a few days in culture. Choline-based metabolites were not affected by growth. Treatment with the antitumor drug lonidamine, which blocks cell proliferation and cell progression through cycle, increased lipid signal intensity. Morphological changes in the organization of the cell surface were detected by scanning electron microscopy during exponential growth, and were confirmed by freeze fracture analysis. The observed metabolic and structural modifications during cell growth were correlated to cell cycle progression of HeLa cells, as high-intensity lipid signals were typical of cells with a high percentage of S- and( )G(2) + M-phases, while cells with a high frequency in G(1)-phase were characterized by mobile lipid signals of very low intensity. Magn Reson Med 42:248-257, 1999.

Antineoplastic Agents↗

PubMed1999