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Biomedical subjects

A Taddei

Publications and source records attributed to A Taddei.

At least 19 recordsLinked to original sources
PubMed2002

[Estrogen and progesterone receptors in meningiomas: immunohistochemical (Mib-1, p53) and clinico-morphological correlations].

We studied 98 meningiomas including 89 benign, 5 atypical, and 4 anaplastic tumors to determine the immunohistochemical expression of estrogen and progesterone receptors and its prognostic value in comparison to histological grade, Mib-1 and p53. Estrogen and progesterone receptor positivity was observed in 63% and 5% of the cases, respectively. In 79% of meningiomas only a minimal proliferative activity was documented, whereas in 36% we detected an overexpression of the p53 oncoprotein. Anaplastic meningiomas were constantly negative for PgR, ER, and highly positive for Mib-1; 75% were positive for p53. A statistical correlation was demonstrated between p53 protein and Mib-1. Specifically the p53-negative meningiomas were frequently negative for Mib-1 (p = 0.002); conversely the lesions strongly positive for Mib-1 were p53-positive (p = 0.001).

Adult↗
PubMed2001

From snapshots to moving pictures: new perspectives on nuclear organization.

The positioning of chromosomal domains in the interphase nucleus is proposed to facilitate gene regulation in simple cells such as yeasts and to coordinate patterns of gene expression and activation of origins of replication during cell differentiation in complex organisms. Over the past 10-12 years, detailed information on the organization of interphase chromosomes has accumulated from three-dimensional microscopy of fixed cells labeled by in situ hybridization and immunofluorescence techniques. Recently, time-lapse fluorescence microscopy of GFP-tagged domains has shown that interphase chromatin can be highly dynamic, moving distances >0.5 microm within seconds. Novel fluorescence techniques show that most nuclear proteins are also highly mobile. Both the rapid oscillations of chromatin and long-range movements of chromosomes suggest new mechanisms for spatial and temporal control of transcription and other nuclear events.

Animals↗
PubMed2001

Reversible disruption of pericentric heterochromatin and centromere function by inhibiting deacetylases.

Histone modifications might act to mark and maintain functional chromatin domains during both interphase and mitosis. Here we show that pericentric heterochromatin in mammalian cells is specifically responsive to prolonged treatment with deacetylase inhibitors. These defined regions relocate at the nuclear periphery and lose their properties of retaining HP1 (heterochromatin protein 1) proteins. Subsequent defects in chromosome segregation arise in mitosis. All these changes can reverse rapidly after drug removal. Our data point to a crucial role of histone underacetylation within pericentric heterochromatin regions for their association with HP1 proteins, their nuclear compartmentalization and their contribution to centromere function.

Animals↗
PubMed2000

Bioactivity studies of extracts from Tridax procumbens.

An updated review on the biological activity of Tridax procumbens is presented. A detailed biological screening comprised of gram-positive and gram-negative bacteria, yeasts and fungi using crude extracts of this plant was undertaken. The n-hexane extract of the flowers showed activity against Escherichia coli. The same extract of the whole aerial parts was active against Mycobacterium smegmatis, Escherichia coli, Salmonella group C and Salmonella paratyphi. The ethyl-acetate extract of the flowers was active against Bacillus cereus and Klebsiella sp. The aerial parts extract also showed activity only against Mycobacterium smegmatis and Staphylococcus aureus, while the aqueous extract showed no antimicrobial activity. None of the tested extracts was active against the yeasts, Candida albicans, Candida tropicalis and Rhodotorula rubra; or the fungi: Aspergillus flavus, Aspergillus niger, Mucor sp. and Trichophyton rubrum.

Anti-Bacterial Agents↗
PubMed1999

Duplication and maintenance of heterochromatin domains.

To investigate the mechanisms that assure the maintenance of heterochromatin regions, we took advantage of the fact that clusters of heterochromatin DNA replicate late in S phase and are processed in discrete foci with a characteristic nuclear distribution. At the light microscopy level, within these entities, we followed DNA synthesis, histone H4 acetylation, heterochromatin protein 1 (Hp1alpha and -beta), and chromatin assembly factor 1 (CAF-1). During replication, Hp1alpha and -beta domains of concentration are stably maintained, whereas heterochromatin regions are enriched in both CAF-1 and replication-specific acetylated isoforms of histone H4 (H4Ac 5 and 12). We defined a time window of 20 min for the maintenance of this state. Furthermore, treatment with Trichostatin A (TSA), during and after replication, sustains the H4Ac 5 and 12 state in heterochromatin excluding H4Ac 8 and 16. In comparison, early replication foci, at the same level, did not display any specific enrichment in H4Ac 5 and 12. These data emphasize the specific importance for heterochromatin of the replication-associated H4 isoforms. We propose that perpetuation of heterochromatin involves self-maintenance factors, including local concentration of Hp1alpha and -beta, and that a degree of plasticity is provided by the cycle of H4 acetylation/deacetylation assisted by CAF-1.

Acetylation↗
PubMed1999

Antimicrobial activity of Wedelia trilobata crude extracts.

A biological screening of activity against Gram-positive and Gram-negative bacteria, yeasts, and fungi of crude extracts from Wedelia trilobata is reported. The n-hexane extract showed antibacterial activity against Bacillus subtilis, Mycobacterium smegmatis, Staphylococcus aureus, and Staphylococcus epidermidis (Gram-positive bacteria); along with Proteus vulgaris, Pseudomonas aeruginosa, Salmonella group C, Salmonella paratyphi, and Shigella sonnei (Gram-negative bacteria). The ethyl acetate extract was active only against Salmonella group C; and the aqueous extract was inactive against the tested bacteria. None of the tested extracts showed biological activity against the yeasts (Candida albicans, Candida tropicalis, Rhodotorula rubra) or the fungi (Aspergillus flavus, Aspergillus niger, Mucor sp., Trichophyton rubrum).

Anti-Bacterial Agents↗
PubMed1999

C3: Java-based medical record system for cardiology.

This paper describes a system for electronic medical record (EMR) we have developed for use in our health care institution, mainly dealing with diagnosis and treatment of cardiovascular pathologies. This activity is part of the project SPERIGEST, supported by Health Ministry of Italy, for the management of health care delivery, as concerns both clinical and administrative aspects. A networked computer-based information system was realized to integrate the different heterogeneous sources of patient information. Both clinical and administrative patient relevant data are provided from the various systems and stored into a central database. The EMR system was designed using World Wide Web (WWW) technology (Java, HTML). The system is currently under clinical evaluation.

Cardiology↗
PubMed1997

Glucocorticoids and the immune function in the human immunodeficiency virus infection: a study in hypercortisolemic and cortisol-resistant patients.

Immunological studies in human immunodeficiency virus (HIV)-positive patients suggest that the disease progression is accompanied by a defective production of type 1 cytokines (interleukin-2 (IL-2) and IL-12], an increased production of type 2 cytokines (IL-4, IL-6, and IL-10), and an increased production of IgE. HIV infection is also associated with activation of the hypothalamo-pituitary-adrenal axis function and increased plasma and urinary cortisol concentrations. As cortisol is involved in the physiological regulation of cytokines, a study was conducted to examine cytokine patterns in two groups of hypercortisolemic patients, one with normal sensitivity to glucocorticoids and the other with glucocorticoid resistance. Ten HIV-infected patients with normal receptor affinity to glucocorticoids (AIDS-C), 10 HIV-infected patients with low receptor affinity to glucocorticoids (AIDS-GR), and 20 healthy subjects were studied. Receptor characteristics of peripheral blood mononuclear cells were evaluated by [3H]dexamethasone binding. Serum cortisol and urinary free cortisol were measured by RIA. Serum ACTH and IgE were measured by immunoradiometric assay, and IL-2, IL-4, and IL-10 cytokines and interferon-gamma were measured by enzyme-linked immunosorbent assay. AIDS-C patients showed low IL-2 and high IL-4, IL-10, and IgE concentratios; conversely, AIDS-GR patients showed high IL-2 and low IL-4 and IgE concentrations. Thus, in HIV infection, elevated cortisol levels suppress cell-mediated immunity and stimulate humoral immunity, whereas this response is not detected in cortisol-resistant patients. These findings indicate that cortisol and its receptors are critically involved in the regulation of immune function in HIV infection.

Adrenocorticotropic Hormone↗
PubMed1995

Classification of arrhythmic events in ambulatory electrocardiogram, using artificial neural networks.

We propose artificial neural networks (ANN) for ambulatory ECG arrhythmic event classification, and we compare them with some traditional classifiers (TC). Among them, the one based on the median method (heuristic algorithm) was chosen and taken as a quality reference in this study, while a back propagation based classifier, designed as an autoassociator for its peculiar capability of rejecting unknown patterns, was examined. Two tests were performed: the first to discriminate normal vs ventricular beats and the second to distinguish among three classes of arrhythmic events. The results show that the ANN approach is more reliable than the traditional classifiers in discriminating among many classes of arrhythmic events: 98% by ANN vs 99% by a TC for correctly classified normal beats, 98% by ANN vs 96% by TC for correctly classified ventricular ectopic beats, 96% by ANN vs 59% by TC for correctly classified supraventricular ectopic beats, and 83% by ANN vs 86% by median method for correctly classified aberrated atrial premature beats. This paper also tackles the problem of the management of classification uncertainty. Two concurrent uncertainty criteria have been introduced, to reduce the classification error of the unknown ventricular and supraventricular arrhythmic beats respectively. The error in ventricular beats case was kept close to 0% in average and for supraventricular beats was kept at 35% in average. So we can state that the ANN approach is powerful in classifying beats represented in the training set and that it manages the uncertainty in such a way as to reduce, in any case, the global error percentage.

Algorithms↗
PubMed1994

Synthesis of C(10)-halogenated prostaglandins.

The synthesis of halogenated prostaglandins at position C(10), starting from prostaglandin A2, has been accomplished, as well as an efficient regioselective hydroxylation of the upper chain of the prostanoid structure. Evaluation of the inhibitory effects on the proliferation of the K-562 cell line in vitro is presented. When the prostaglandin was modified in the upper chain, the antimitotic activity for bromo derivatives 4b, c and iodo derivative 5b had shown substantial improvements in their activities according to their ID50 values (28, 25, and 22 micrograms/mL, respectively). Attention is called to the significance of chloro derivative 3a in terms of its high potency, determined by its ID50 value (0.06 micrograms/mL).

Acetylation↗
PubMed1992

The European ST-T database: standard for evaluating systems for the analysis of ST-T changes in ambulatory electrocardiography.

The project for the development of the European ST-T annotated Database originated from a 'Concerted Action' on Ambulatory Monitoring, set up by the European Community in 1985. The goal was to prototype an ECG database for assessing the quality of ambulatory ECG monitoring (AECG) systems. After the 'concerted action', the development of the full database was coordinated by the Institute of Clinical Physiology of the National Research Council (CNR) in Pisa and the Thoraxcenter of Erasmus University in Rotterdam. Thirteen research groups from eight countries provided AECG tapes and annotated beat by beat the selected 2-channel records, each 2 h in duration. ST segment (ST) and T-wave (T) changes were identified and their onset, offset and peak beats annotated in addition to QRSs, beat types, rhythm and signal quality changes. In 1989, the European Society of Cardiology sponsored the remainder of the project. Recently the 90 records were completed and stored on CD-ROM. The records include 372 ST and 423 T changes. In cooperation with the Biomedical Engineering Centre of MIT (developers of the MIT-BIH arrhythmia database), the annotation scheme was revised to be consistent with both MIT-BIH and American Heart Association formats.

Algorithms↗
PubMed1987

[Methods of the elaboration of data of the cardiological importance].

This paper deals with some introductory topics of signal processing and decision making in cardiology. In both instances the matter is referred to general schemes well suited to host different applications. Signal processing is divided in some phases: acquisition, storing, analysis and each of them is described with applications to specific signals. In a similar manner the methods for decision making have been simplified to a scheme including a "knowledge base" and an "inference method". The scheme is used to classify various implementations. Bayes analysis and expert systems have been introduced with some details.

Data Interpretation, Statistical↗
PubMed1987

[Technical ambulatory ECG innovations in performance evaluation].

Evaluating the performances of the instrumentation for Ambulatory ECG (AECG) analysis is a need largely recognized by both manufacturers and users. The most generally accepted method is the beat-by-beat comparison with annotated data bases, representing the different ECG abnormalities. Available data bases are aimed at arrhythmias detection evaluation, while it is recognized that the AECG ST-T changes detection has a great relevance in the analysis of ischemic heart disease. A concerted action of the European Community on Ambulatory Monitoring has been approved for achieving a comprehensive reference standard for assessing the quality of AECG instrumentation. The European project has been concentrated on the problem of ST-T analysis. An annotated data base is being developed with the contribution of european experts. A pilot study has been performed for establishing the criteria related to the development and annotation; particularly the definition of significant ST-T changes has been established. The data base will include 2-hour double channel AECG records, which contain at least one ST-T episode. Each record is annotated beat by beat according to the established scheme, identifying arrhythmic beats, rhythm changes, ST-T changes and noisy segments. A coordinating center has been established for interacting with the participating groups and for performing the operations related to the generation and management of the data base. For the time being 14 Groups of 8 Countries are participating to the annotation of the data base. A minimum number of 100 records is planned within June 1988.

Algorithms↗
PubMed1987

[Analysis of the market and future trends of the instrumentation for ambulatory electrocardiography].

An inquiry has been made among most manufacturers of ambulatory ECG instrumentation. Both playback and real time systems have been considered. The inquiry, based on a questionnaire, was mainly aimed at identifying possible standard technical solutions emerging from the analysis of various implementations, and at verifying whether techniques for performance evaluation are in common use. Main conclusions of this study include: playback systems are still in competition with real time systems; automatic analysis has not yet reached adequate accuracy; analysis of ST-T interval, while performed by most systems, is not evaluated because common standard of quality is lacking.

Algorithms↗
PubMed1985

Electrocardiogram blood pressure and systolic time intervals long term monitoring in ambulant patients.

Ambulatory monitoring of the intra arterial blood pressure (IBP), through the Selyg-Oxford System, has been used so far primarily for studies on hypertension. Aim of our study is to explore the possibility of obtaining from IBP indications useful to extend its field of application. The study will investigate: the usefulness of the continuous monitoring of the systolic time intervals (STI), measured from IBP as ventricular performance indicators, the increasing of specificity of the ECG allowed by the simultaneous beat by beat estimate of the STI's, the possibility of achieving the same information from non invasive peripheral pressure transducers. In this paper we are presenting the results obtained from the combined analysis of the STI's, ECG and IBP in a first series of 13 patients, selected out of 50 on the basis of the highest number of episodes of IBP variations, to allow the evaluation of the algorithms performances in severe conditions.

Blood Pressure↗
PubMed1983

[Anterior joints of the thoracic cage].

The chondro-sternal, interchondral, costo-chondral joints and the upper and lower sternal joints were studied in the thorax of 60 children and human adults. Chondro-sternal joints occur as frequent symphyses in the 5th, 6th and 7th joints or ellipsoid joints which are mainly found in the 2nd, 3rd and 4th joints. Diarthrosis frequency increases with age in every joint. An articular space appears particularly in the lower part of the 2nd, 3rd and 4th joints; in fewer cases a space is found in the upper part of the 5th, 6th and 7th joints. These partial spaces disappear with age and are replaced by spaces occupying the whole articulation. The first joint is a synchondrosis which does not vary with age. Interchondral joints are diarthrodial or trochoid joints from earliest childhood and their frequency increases with age. No direct articular contact was observed between the 9th and 10th costal cartilages. Costo-chondral joints are synarthrosis. The upper sternal joint, which is a synchondrosis in the child, may develop into a non-synovial cavity with age, or even turn into synostosis. The lower sternal joint is a synchondrosis which develops partially towards synostosis.

Adult↗