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S Fabbri

Publications and source records attributed to S Fabbri.

At least 19 recordsLinked to original sources
PubMed2003

Dual-energy imaging in full-field digital mammography: a phantom study.

A dual-energy technique which employs the basis decomposition method is being investigated for application to digital mammography. A three-component phantom, made up of plexiglas, polyethylene, and water, was doubly exposed with the full-field digital mammography system manufactured by General Electric. The 'low' and 'high' energy images were recorded with a Mo/Mo anode-filter combination and a Rh/Rh combination, respectively. The total dose was kept within the acceptable levels of conventional mammography. The first hybrid images obtained with the dual-energy algorithm are presented in comparison with a conventional radiograph of the phantom. Image-quality characteristics at contrast cancellation angles between plexiglas and water are discussed. Preliminary results show that a combination of a standard Mo-anode 28 kV radiograph with a Rh-anode 49 kV radiograph provides the best compromise between image-quality and dose in the hybrid image.

Algorithms↗
PubMed2002

Signal-to-noise ratio evaluation in dual-energy radiography with synchrotron radiation.

Dual-energy radiography is an effective technique that allows removal of contrast between pairs of materials in order to display details of interest on a uniform background. In mammographic images the detection of small nodules is often impeded by obscuring background 'clutter' resulting from the contrast between normal tissues (glandular and adipose) in their neighbourhood. We consider whether it could be possible to apply dual-energy radiography to the breast, which is hypothetically principally composed of three tissues, glandular, adipose and cancerous, in order to remove the contrast due to the distribution of normal tissues and, as a consequence, to enhance the intrinsic contrast of the pathology. The purpose of this work is to test the limitations of dual-energy radiography on a three-component phantom under optimum conditions of the source and detector. We use a synchrotron monochromatic beam, produced at the ELETTRA synchrotron facility (Trieste, Italy), and an imaging plate detector, in order to acquire two images at low and high energies of a phantom composed of polyethylene, plexiglas and water. For evaluation of the potential of this procedure we studied the signal-to-noise ratio (SNR) of polyethylene and water on a set of images obtained by applying the dual-energy procedure. We found that the SNR of polyethylene and water is around the detectability threshold (according to Rose's criteria) at the contrast cancellation angles. Finally we evaluated the air entrance dose required for this double exposure, resulting in 0.81 mGy for the low-energy image and 0.01 mGy for the high-energy image. To obtain the same image quality for a standard breast of 5.5 cm, mean glandular doses of 3.50 mGy and 0.03 mGy at 17 keV and at 34 keV, respectively, are required.

Algorithms↗
PubMed2001

Electromagnetic field monitoring and control systems: state-of-the-art and work-in-progress.

The development of EMF monitoring and control systems unquestionably represents one of the major innovations in the range of methodologies for evaluating, through measurement, the so-called environmental electromagnetic pollution. The interest recently shown by ARPA and municipal and provincial councils for setting up electromagnetic field monitoring and control systems has created significant developments in the field under examination. This paper attempts to provide a complete overview of the technical possibilities provided by electromagnetic field monitoring and control systems in the environment and their possible applications. Equipment currently available and under development is described, as well as the most significant work-in-progress in this sector. In the near future, several monitoring systems will be proposed and set up by municipalities and provinces, or directly by telecommunications companies. For this reason, it is more than ever necessary that agreement be reached at a national level to define a unified methodological and operating approach to enable monitoring data from different sources to be compared.

Electromagnetic Fields↗
PubMed2000

Comparison of different immunoaffinity clean-up procedures for high-performance liquid chromatographic analysis of ochratoxin A in wines.

Three immunoaffinity clean-up procedures to analyse ochratoxin A (OTA) in wines were compared. The direct wine clean-up with Ochraprep and OchraTest columns gave equivalent results in terms of recovery and precision if compared with the reference procedure involving a preliminary extraction of OTA with chloroform. OTA quantification limit in wine ranged from 0.020 to 0.045 microg/l. The 'on-flow' OTA emission spectrum (excitation 333 nm) showed a maximum at 460 nm and could be used to confirm the quantitative results. The analysis of 11 red and white wines gave no significant quantitative differences between the three clean-up techniques.

Chromatography, Affinity↗
PubMed2000

Explanatory therapy in hypochondriasis.

OBJECTIVE: The aim of the study was to evaluate the effectiveness of individual explanatory therapy in hypochondriasis. METHOD: Twenty patients with DSM-IV hypochondriasis were randomly assigned to 2 groups. One received explanatory therapy and was assessed again after a 6-month follow-up. The other was first assigned to a waiting list and subsequently treated with explanatory therapy. All patients received usual medical care from their physicians. Assessments involved both observer and self-rated instruments. RESULTS: In both groups, explanatory therapy was significantly associated with a reduction of hypochondriacal fears and beliefs, improvement in affective disturbances and anxiety sensitivity, and a decrease in health care utilization. Therapeutic gains were maintained at follow-up. Substantial residual symptomatology, however, remained. CONCLUSION: The results suggest that hypochondriasis is a treatable condition and that explanatory therapy is a viable therapeutic tool. Further research should disclose the actual components of the mechanism of change in hypochondriacal patients.

Adult↗
PubMed1998

Conservation of substrate recognition mechanisms by tRNA splicing endonucleases.

Accuracy in transfer RNA (tRNA) splicing is essential for the formation of functional tRNAs, and hence for gene expression, in both Eukaryotes and Archaea. The specificity for recognition of the tRNA precursor (pre-tRNA) resides in the endonuclease, which removes the intron by making two independent endonucleolytic cleavages. Although the eukaryal and archaeal enzymes appear to use different features of pre-tRNAs to determine the sites of cleavage, analysis of hybrid pre-tRNA substrates containing eukaryal and archaeal sequences, described here, reveals that the eukaryal enzyme retains the ability to use the archaeal recognition signals. This result indicates that there may be a common ancestral mechanism for recognition of pre-tRNA by proteins.

Animals↗
PubMed1997

The eucaryal tRNA splicing endonuclease recognizes a tripartite set of RNA elements.

The tRNA splicing endonuclease cleaves intron-containing tRNA precursors on both sides of the intron. The prevailing belief has been that the enzyme binds only to the mature domain through the invariant bases. We show instead that, for recognition, the endonuclease utilizes distinct sets of structural elements, several of which are within the intron. One subset of recognition elements, localized in the mature domain, is needed for recognition of both cleavage sites, while two other subsets, localized at the exon-intron boundaries, are used for recognition of either one or the other cleavage site. The two cleavage sites are essentially independent: neither is required by the other for cleavage to take place. These results support a two-active-site model for the eucaryal endonuclease.

Base Sequence↗
PubMed1994

Transfer kinetics and coefficients of 90Sr, 134Cs, and 137Cs from forage contaminated by Chernobyl fallout to milk of cows.

A experiment was conducted to study kinetics, transfer coefficients, and biological half-lives of 90Sr, 134Cs, and 137Cs from feed to milk. A cow was fed a diet containing alfalfa hay contaminated by Chernobyl fallout for 14.5 wk. The time-dependent activity in milk was approximated by a two-compartment model with fast biological half-lives of 2, 0.9, and 1 d and slow biological half-lives of 36.9, 8.7, and 12.4 d for 90Sr, 134Cs, and 137Cs, respectively. The transfer coefficients determined in the experiment were 0.0008 d L-1 for 90Sr, 0.0029 d L-1 for 134Cs, and 0.0031 d L-1 for 137Cs. The biological elimination phases of 134Cs and 137Cs were described by a two-compartment model while a one-compartment model was proposed for 90Sr.

Accidents↗
PubMed1993

In vitro genetic analysis of the structural features of the pre-tRNA required for determination of the 3' splice site in the intron excision reaction.

During processing of intron-containing pre-tRNAs, the Xenopus laevis splicing endonuclease binds the precursor and cleaves it at both the 5' and 3' splice sites. In vitro selection was used to determine structural features characteristic of precursor tRNA molecules that are active in this reaction. We performed two types of selection, one for molecules that are not cut, the other for molecules that are cut at only one site. The results shed light on various aspects of the intron excision reaction, including the importance of the three-dimensional structure of the mature domain for recognition and binding of the enzyme, the active role played by the single-stranded region of the intron, and the importance of the cardinal positions which, although not necessarily occupied by the same base in all precursors, nevertheless play a fundamental role in the splicing reaction. A precursor can be cut at the 3' site if a base in the single-stranded loop of the intron is allowed to pair (A-I pair) with the base of the 5' exon situated at the position immediately following the anticodon stem [first cardinal position (CP1)]. The nature of the bases involved in the A-I pair is important, as is the position of the base in the single-stranded loop of the intron. We discuss the role of the cardinal positions in the reaction.

Animals↗
PubMed1993

Differential inhibition of the DNA binding of transcription factors NF kappa B and OTF-1 by nitrogen mustard and quinacrine mustard: transcriptional implications.

Nitrogen mustard (HN2) and quinacrine mustard (QM) both inhibited the binding of NF kappa B to the GC-rich consensus sequence in the HIV long terminal repeat (LTR), as assessed by gel-shift assays. QM also inhibited the binding of OTF-1 to the AT-rich octamer present in the H2B promoter whereas HN2 was inactive. Inhibition of the binding of transcription factors was due to the drug interaction with DNA, since it also occurred when transcription factors were added to DNA after removal of free drug. In Jurkat cells transfected with pI3CAT, where the chloramphenicol acetyltransferase (CAT) gene is under the control of the HIV LTR, both HN2 and QM inhibited CAT gene expression. However, in Jurkat cells transfected with plasmid -147, where the CAT gene is under the control of the H2B promoter, QM inhibited CAT expression but HN2 did not. These results were obtained at concentrations of HN2 or QM that inhibited total DNA and RNA synthesis to a similar extent. The present results suggest that the more selective pharmacological activity of HN2 (HN2 is an active antineoplastic agent whereas QM is inactive and very toxic) might be related to its preferential functional inhibition of GC-rich consensus sequence, possibly important in the regulation of genes involved in the malignant proliferation and behavior of some tumors.

Base Composition↗
PubMed1992

Participation of the intron in the reaction catalyzed by the Xenopus tRNA splicing endonuclease.

Introns have generally been assumed to be passive in the transfer RNA splicing reaction. Experiments have now been done showing that the endonuclease is able to cut a precursor provided that a base in the single-stranded loop of the intron can pair with the base of the 5' exon situated at the position that immediately follows the anticodon stem (position 33 in the yeast tRNA isoacceptor pre-tRNA(Leu)3, position 32 in yeast pre-tRNA(Phe)). The elucidation of the role of the intron reveals that in addition to the conserved bases, there are positions in the mature domain which, although not necessarily occupied by the same base in all pre-tRNA's, nevertheless have a fundamental role in the splicing reaction. These positions are termed cardinal positions.

Animals↗
PubMed1968

Isolation of crustecdysone (20R-hydroxyecdysone) from a crayfish (Jasus lalandei H. Milne-Edwards).

1. A small amount (2mg.) of crustecdysone, a moulting hormone of crustaceans, was isolated from 1 ton of crayfish waste. 2. The purification procedure used was developed with the aid of crustacean and insect bioassays. 3. CM-Sephadex was found to be superior to Sephadex and very effective for the chromatographic separation of crustecdysone from other non-ionic compounds. The higher efficiency of CM-Sephadex is attributed to the greater number of carboxyl groups available for hydrogen-bonding. 4. Reversed-phase chromatography, with butan-1-ol-cyclohexane mixtures as the stationary phase and water as the flowing phase, proved superior to countercurrent distribution with these solvents for the fractionation of purified extracts. 5. A second moulting hormone, deoxycrustecdysone, and the red-concentrating hormone were obtained in a partially purified form.

Animals↗
PubMedDate not supplied

Psychological evaluation after cardiac transplantation: the integration of different criteria.

BACKGROUND: The psychological evaluation of patients undergoing cardiac transplantation is currently based on DSM-IV criteria. An alternative diagnostic and conceptual framework has been proposed by an international group of psychosomatic investigators. The aim of this study was to compare these new criteria (Diagnostic Criteria for Psychosomatic Research, DCPR) with DSM-IV in a population where a high prevalence of psychological problems is expected (heart-transplanted patients). METHOD: 129 consecutive patients who underwent heart transplant surgery were assessed according to DSM-IV and DCPR criteria. RESULTS: The results showed a higher number of diagnoses made using the DCPR than with the use of the DSM-IV. At least one DCPR diagnosis was found in 85 (66%) patients, whereas at least one DSM diagnosis was present in 23 (18%) patients. The number of DCPR diagnoses was almost the triple of DSM criteria. While patients who were given a DSM diagnosis frequently had additional DCPR diagnoses, many patients with DCPR criteria did not fulfill any DSM criteria. Four DCPR syndromes appeared to be particularly frequent: demoralization, type A behavior, irritable mood and alexithymia. CONCLUSIONS: The joint use of DSM and DCPR criteria was found to improve the identification of psychological factors which could result in a worsening of quality of life in heart-transplanted patients.

Affective Symptoms↗
PubMedDate not supplied

Emotional, cognitive, and behavioral characteristics of medical outpatients: a preliminary analysis.

The authors examined the relationship among emotional, cognitive, and behavioral factors in 65 new outpatients attending neurology and cardiology clinics. The patients completed the Hospital Anxiety and Depression Scale, the Illness Perception Questionnaire, the Somatosensory Amplification Scale, the Private Body Consciousness Scale, and the Health Anxiety Questionnaire. A principal component factor analysis revealed two factors, somatosensory amplification/anxiety and depression/pessimism, that together accounted for 44% of the variance. The factors the authors identified may be useful as a basis for understanding different patterns of illness behavior. The use of these factors may help to rationalize and refine the large number of existing measures and simplify the assessment process, as well as contributing to the development of treatment interventions.

Adolescent↗