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Biomedical subjects

J Esposito

Publications and source records attributed to J Esposito.

15 recordsLinked to original sources
PubMed2005

Preliminary design of a Gd-NCT neutron beam based on compact D-T neutron source.

Gadolinium has been recently proposed, as neutron capture agent in NCT (Neutron Capture Therapy), due to both the nuclide high neutron capture cross section, and the remarkable selective uptake inside tumour tissue that Gd-loaded compounds, can provide. When a neutron external source is supplied, different Gd nuclear reactions, and the generated Auger electrons in particular, cause a high local energy deposition, which results in a tumour cell inactivation. Preliminary micro- as well as macrodosimetric Monte Carlo computational investigations show that the tumour-to-healthy tissue biological damage ratio is in close relation to the neutron beam energy spectrum. The results points out that the optimum neutron spectrum, to be used for Gd-NCT, seems to lie in the 1 to 10 keV energy range. In order to 'tailor' such spectra, an original, accelerator-driven, neutron source and spectrum shaping assembly for hospital-based Gd-NCT are presented and preliminary results are reported.

Brain Neoplasms↗
PubMed2004

BNCT microdosimetry at the tapiro reactor thermal column.

A thermal column is available for dosimetric and radiobiological studies by the fast reactor TAPIRO, located at the ENEA research centre Casaccia. The TAPIRO neutron field has been studied (in the frame of LNL BNCT project) with a tissue-equivalent proportional counter, which has worked alternatively with an ordinary tissue-equivalent cathode and with a boron-enriched cathode. Measurements have been performed with polyethylene caps of different thickness. Both the absorbed dose and the microdosimetric-calculated biological effective dose show a maximum at approximately 0.5 mg cm(-2) of depth. The different dose components have been calculated and the results are discussed.

Body Burden↗
PubMed1997

[Ambulatory anesthesia practice in a University Hospital Center: what is done; what could be done. Ambulatory Anesthesia Study Group].

OBJECTIVES: To estimate the number and type of patients, who could be managed on a day-care basis in a University Hospital. Cases of ambulatory anaesthesia (AA) which could be managed in optimal conditions and current AA practice. To assess patients' opinion on inpatient or outpatient practices. STUDY DESIGN: Prospective survey over 8 weeks in 21 medical units potentially concerned by ambulatory practice. PATIENTS: Series of 1,396 patients undergoing an operation included in a previously established list of outpatient procedures. METHOD: A questionnaire was completed for each patient, from preoperative anaesthesia consultation until discharge. Thereafter patients were contacted after home discharge by telephone or mail. RESULTS: In the group of the 1,396 selected patients, 301 (22%) were contra-indicated for AA. In optimal conditions AA was indicated in 20% of all patients treated in these units. At the time of the survey there were 285 outpatients (26% of potential AA, 5% of all patients). Complications were uncommon. Ninety-eight percent of them would choose day surgery again. Among the 810 inpatients, 279 responded: 53% would prefer to be an ambulatory patient. CONCLUSION: At the time of this survey only one fourth of the possible oupatients for AA had in fact been treated on a day-case basis. Its development requires an improvement of the structures, team organisation and patients' information.

Adolescent↗
PubMed1991

A single nucleotide substitution in the 5'-untranslated region of the vaccinia N2L gene is responsible for both alpha-amanitin-resistant and temperature-sensitive phenotypes.

The locus responsible for encoding resistance to alpha-amanitin was previously mapped to the vaccinia virus (VV) HindIII N fragment by using cloned wild-type VV DNA fragments to rescue the ability of an alpha-amanitin-resistant/temperature-sensitive VV mutant (alpha rts7) to replicate under nonpermissive conditions. DNA sequencing and transcriptional analyses of this region identified two leftward-reading open reading frames (ORFs), N2L and M1L, as candidates to encode the protein responsible for eliciting both phenotypes. In the present study, high-resolution marker rescue mapping and genomic sequencing techniques have been applied to identify the nature of the mutation within the HindIII N region of the alpha rts7 genome. Interestingly, a single G to T transversion mutation was noted at position -10 relative to the initiator ATG of the N2L ORF. Since transcription of the N2L gene starts at position -12/-13, this places the alpha rts7 mutation within the 5'-untranslated leader of the N2L transcript expressed early in infection and suggests that the transcriptional efficiency, mRNA stability, or translational efficiency must be altered in the mutant RNA. These results identify the N2L ORF as the gene responsible for conferring resistance to alpha-amanitin in the alpha rts7 mutant and suggest that the N2L gene product is the viral function that interacts with the host cell nucleus during VV infection.

Amanitins↗
PubMed1988

Propofol anaesthesia alters somatosensory evoked cortical potentials.

This study evaluated the effects of propofol on somatosensory evoked cortical potentials in 20 ASA grade 1 or 2 patients who underwent spinal surgery. Anaesthesia consisted of propofol, dextromoramide, 50% nitrous oxide and oxygen mixture. The induction dose of propofol was 2 mg/kg and was followed by an infusion of 6 mg/kg for the first hour and 3 mg/kg subsequently. Somatosensory evoked cortical potentials were recorded on the scalp and compared to pre-operative values using Student's paired t-test. We observed a significant depression of evoked potential 10 minutes after induction, which continued until the early phase of recovery. Because of its short and quickly reversible action, propofol is an acceptable agent when clinical monitoring of the spinal cord is indicated but is not satisfactory when monitoring has to be based on somatosensory cortical evoked potentials.

Adult↗
PubMed1987

Vaccinia virus recombinants expressing rabiesvirus glycoprotein protect against rabies.

Six recombinants of New York Board of Health (NYBH) vaccinia virus containing cDNA for Challenge Virus Standard (CVS) rabiesvirus glycoprotein (G) were produced by directing gene insertion into the vaccinia thymidine kinase (TK) locus. To regulate expression of G the promoter P7.5 (functions at early and late times postinfection) from the gene for the vaccinia 7.5 kilodalton (kD) protein was used in two of the recombinants; late promoter P11 of the vaccinia 11 kD protein was used in four recombinants. The six differed in nucleotide sequences flanking the translation start codon; in two constructs the encoded signal peptide of G was fused to several additional amino acids. Cells infected with each recombinant made G that reacted with G-specific antibodies, comigrated with authentic G, and was transported to the plasma membrane. The highest amounts of G were made with fusion or standard versions of G with P11 provided that the mRNA leader sequences were identical to the natural gene. Each recombinant in mice and one in dogs induced rabiesvirus neutralizing antibodies and protection against lethal rabiesvirus challenge.

Amino Acid Sequence↗
PubMed1987

[Propofol versus methohexital in the surgery of the spinal canal].

The aim of this study was to compare the quality of postanaesthetic recovery after anaesthesia with methohexitone (M) or with propofol (P). Thirty patients undergoing spinal surgery were randomly assigned to either group. The induction dose was 2 mg . kg-1 for both M and P. Anaesthesia was maintained by continuous infusion. The rate was 0.15 mg . kg-1 . min-1 for P and 0.07 mg . kg-1 . min-1 for M. Analgesia was obtained with fentanyl with the same doses in both groups. The maintenance doses were subsequently decreased by 50 and 75% of the initial values. This work compared the quality induction and the criteria of recovery (Aldrete score, Newman test). In two patients in each group, sensory evoked potentials (SEP) were recorded to monitor neurological integrity. The quality of induction was similar in both groups. Awakening was significantly more rapid in group P. The SEP were much decreased in group P, whilst there were few changes in group M. Monitoring of medullar integrity is mandatory in spinal surgery, requiring a rapid recovery. This objective was obtained with shorter delays in patients anaesthetized with propofol than in those who had received methohexitone. However, the former, at the doses used, seemed to depress the SEP.

Adult↗
PubMed1983

Effects of dietary magnesium on the development of hypertension in the spontaneously hypertensive rat.

The effect of varying the amount of dietary magnesium on the development of hypertension in spontaneously hypertensive (SH) rats was investigated with three diets containing 1.05% (H1Mg diet), 0.52% (H2Mg diet), and 0.008% (LMg diet). The control group was given a diet containing a normal amount of magnesium (0.2%). When the diet was sufficiently supplemented with magnesium (H1Mg diet), the development of hypertension was significantly slowed and the heart rate slightly lowered. With dietary magnesium depletion (LMg diet), the heart rate was accelerated and hypertension developed more rapidly. Excretion of urinary electrolytes (calcium, magnesium, and sodium) was increased by rats fed the H1Mg diet and decreased by rats on the LMg diet. Urinary cAMP was decreased both on the HMg diets and on the LMg diet. With the H1Mg diet, total and ionized calcium and sodium levels in plasma fell, and magnesium plasma levels rose. Rats fed the LMg diet had increased total and ionized calcium and decreased magnesium plasma levels. These results show that dietary magnesium modifies the metabolism of calcium, sodium, magnesium, which can modulate the development of genetic hypertension.

Animals↗
PubMed1975

Adipose tissue blood flow and cellularity in the growing rabbit.

Resting blood flow was measured in isolated, innervated, epigastric fat-pads of 27 male rabbits during growth in the 1st yr of life and found to vary widely in range (7.6-28.1 ml/100 g tissue per min). Definition of adipose tissue composition and of fat-cell size and number made it possible to explain the wide range of flow and to identify two types of relationships between adipose blood flow and tissue constituents. Expressed in the usual manner (ml/100 g tissue per min), adipose blood flow declined with increasing adiposity of the fat depots, and a negative correlation was found between flow and fat-cell volume (r equals -.571, P less than .01). In contrast, when blood flow was expressed on the basis of fat-cell number (ml/108 fat cells/min), a positive and highly significant correlation was found between blood flow per fat cell and fat-cell volume (r equals .842, P less than .001). In the rabbit tissue the relationship of blood flow to fat-cell number and size was more predictable than the usual expression of flow in terms of tissue wet weight. Food deprivation for 18-24 h did not significantly alter these relationships. The results indicate that changes in adipose tissue composition and cellularity, resulting from growth and from accumulation of lipid in enlarging adipocytes, are important determinants of blood flow regulation to adipose tissue.

Adipose Tissue↗
PubMed1974

Metabolic patterns and insulin responsiveness of enlarging fat cells.

The rate and pattern of glucose metabolism, basal lipolysis, and intracellular concentration of free fatty acids were determined in isolated epididymal fat cell preparations (mean volume 30-800 pl) from rats on the basis of fat cell number and in relation to the cell volume. The effects of increasing glucose concentrations in the medium and of insulin on the cellular metabolic activities were compared. Expanding fat cell volume correlated positively and significantly (P < 0.001) with the synthesis of glyceride glycerol from glucose (correlation coefficient, r = 0.919), with rates of basal lipolysis (r = 0.663), and with intracellular free fatty acid accumulation (r = 0.796); it correlated negatively and significantly with glucose conversion to glyceride fatty acids (r = -0.814, P < 0.01). The differences in patterns of glucose metabolism and basal lipolysis between small (<100 pl) and large (>400 pl) fat cells were not modified by insulin or by increments in glucose concentration. The results indicate that the reduced capacity of the large fat cells to respond to insulin cannot be attributed solely to a limited capacity of the cells to take up and metabolize increasing amounts of glucose. The acquired unresponsiveness of the large cells to insulin may result from an alteration in the mechanism of action of insulin and may be related to an intracellular metabolic derangement with increased basal lipolysis, free fatty acid accumulation, and accelerated glyceride synthesis resulting from the accumulation of triglyceride.

Adipose Tissue↗