Biomedical subjects

L Angelini

Publications and source records attributed to L Angelini.

At least 19 recordsLinked to original sources

PubMed2006

The association of GRB 060218 with a supernova and the evolution of the shock wave.

Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.

Journal Article↗

PubMed2006

Gamma-ray bursts: huge explosion in the early Universe.

Long gamma-ray bursts (GRBs) are bright flashes of high-energy photons that can last for tens of minutes; they are generally associated with galaxies that have a high rate of star formation and probably arise from the collapsing cores of massive stars, which produce highly relativistic jets (collapsar model). Here we describe gamma- and X-ray observations of the most distant GRB ever observed (GRB 050904): its redshift (z) of 6.29 means that this explosion happened 12.8 billion years ago, corresponding to a time when the Universe was just 890 million years old, close to the reionization era. This means that not only did stars form in this short period of time after the Big Bang, but also that enough time had elapsed for them to evolve and collapse into black holes.

Journal Article↗

PubMed2005

A short gamma-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225.

Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars. In contrast, no short GRB had been accurately (< 10'') and rapidly (minutes) located. Here we report the detection of the X-ray afterglow from--and the localization of--the short burst GRB 050509B. Its position on the sky is near a luminous, non-star-forming elliptical galaxy at a redshift of 0.225, which is the location one would expect if the origin of this GRB is through the merger of neutron-star or black-hole binaries. The X-ray afterglow was weak and faded below the detection limit within a few hours; no optical afterglow was detected to stringent limits, explaining the past difficulty in localizing short GRBs.

Journal Article↗

PubMed2005

An unexpectedly rapid decline in the X-ray afterglow emission of long gamma-ray bursts.

'Long' gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which give rise to highly relativistic jets. Inhomogeneities in the expanding flow result in internal shock waves that are believed to produce the gamma-rays we see. As the jet travels further outward into the surrounding circumstellar medium, 'external' shocks create the afterglow emission seen in the X-ray, optical and radio bands. Here we report observations of the early phases of the X-ray emission of five GRBs. Their X-ray light curves are characterised by a surprisingly rapid fall-off for the first few hundred seconds, followed by a less rapid decline lasting several hours. This steep decline, together with detailed spectral properties of two particular bursts, shows that violent shock interactions take place in the early jet outflows.

Journal Article↗

PubMed2005

Bright x-ray flares in gamma-ray burst afterglows.

Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We report the discovery of two bright x-ray flares in GRB afterglows, including a giant flare comparable in total energy to the burst itself, each peaking minutes after the burst. These strong, rapid x-ray flares imply that the central engines of the bursts have long periods of activity, with strong internal shocks continuing for hundreds of seconds after the gamma-ray emission has ended.

Journal Article↗

PubMed2004

Steady-state visual evoked potentials and phase synchronization in migraine patients.

We investigate phase synchronization in EEG recordings from migraine patients. We use the analytic signal technique, based on the Hilbert transform, and find that migraine brains are characterized by enhanced alpha band phase synchronization in the presence of visual stimuli. Our findings show that migraine patients have an overactive regulatory mechanism that renders them more sensitive to external stimuli.

Adult↗

PubMed2004

Phase shifts of synchronized oscillators and the systolic-diastolic blood pressure relation.

We study the phase-synchronization properties of systolic and diastolic arterial pressure in healthy subjects. We find that delays in the oscillatory components of the time series depend on the frequency bands that are considered, in particular we find a change of sign in the phase shift going from the very low frequency band to the high frequency band. This behavior should reflect a collective behavior of a system of nonlinear interacting elementary oscillators. We prove that some models describing such systems, e.g., the Winfree and the Kuramoto models, offer a clue to this phenomenon. For these theoretical models there is a linear relationship between phase shifts and the difference of natural frequencies of oscillators and a change of sign in the phase shift naturally emerges.

Biological Clocks↗

PubMed2004

Subcortical nodular heterotopia: a functional MRI and somatosensory evoked potentials study.

Subcortical nodular heterotopia (SNH) associated with refractory epilepsy may be surgically treated, and a positive outcome can be expected following the complete excision of the malformed tissue. Recent functional neuroimaging studies have suggested the possible functional relevance of cerebral malformations, and may make it possible to improve presurgical planning, thus allowing extended resections and minimising post-operative deficits. We here report the case of a 19-year-old man with epilepsy and a giant SNH associated with diffused abnormal gyrations of the right temporal-parietal regions. Cortical functional organisation was investigated by means of functional magnetic resonance imaging (MRI) during sensory and motor tasks, and somatosensory evoked potentials. The results revealed enlarged and displaced motor and sensory cortical areas with heterotopic tissue functional activation. The relevance of these findings is discussed in the light of the possible surgical treatment of drug-refractory epilepsy associated with cerebral malformations: surgical treatment based on conventional MRI studies alone, without taking the functional nature of dysplastic tissues into account, may lead to considerable side effects.

Adult↗

PubMed2004

Neuromyelitis optica in a child with atypical onset and severe outcome.

We report on a seven-year-old boy with inflammatory relapsing-remitting CNS disease, involving the optic nerves and spinal cord, with increasingly severe sequelae after each relapse. Clinical course, neuroimaging and laboratory findings were consistent with neuromyelitis optica. Biopsy of leptomeninges and underlying nervous tissue showed increased vascularization and thickened hyalinized vessel walls, reported as suggestive for neuromyelitis optica. Clinical features at onset were atypical, rendering the case highly unusual and the diagnosis tentative.

Brain↗

PubMed2004

[Detection, characterization and clinical significance of circulating cancer cells in patients surgically treated for breast cancer].

Recent technological advances have led to an increasing ability to detect isolated or groups of tumour cells in blood, lymph nodes or bone marrow in patients with different tumour types. However, the clinical evidence of these advances is unclear. The detection and the characterisation of circulating breast cancer cells and the eventually micrometastasis represent an important prognostic factor with therapeutic implications. The number of neoplastic cells being very small, these are not easily detected by using only cytomorphology, possibly associated to immunocytochemistry. In the last decade many studies have been directed in order to identify new assays. In the present review the Authors summarize advantages and disadvantages about two different technical approaches: molecular and immunomagnetic selection with cellular enrichment and immunocytochemistry.

Breast Neoplasms↗

PubMed2003

Digital stereotactic biopsies for nonpalpable breast lesion.

BACKGROUND: Percutaneous biopsy (BP) is a valid alternative to open surgical biopsy. The aim of our study was to evaluate the results and diagnostic value of vacuum-assisted core biopsy (VACB; Mammotome) and advanced breast biopsy instrumentation (ABBI). METHODS: From June 1999 to December 2001, 360 BPs were performed: all patients had dubious mammography lesions not confirmed by ultrasonography. Indications were as follows 264 (73.3%) microcalcifications, 64 (17.8%) nodular opacities, and 32 (8.8%) parenchymal distortions. RESULTS: All BPs were performed with a digital stereotactic table with a vacuum suction aspiration system for VACB and a cutting cannula for ABBI. All BPs were correctly performed. Seventy-one (19.7%) lesions were malignant, whereas 258 (71.6%) were benign: 31 (8.6%) of the lesions removed with VACB were atypical ductal hyperplasia. CONCLUSIONS: BP is a valid method for the diagnosis of nonpalpable breast lesions. In our experience, VACB is the method of choice because it is easy to perform and has high adaptability.

Adult↗

PubMed2003

Neonatal dopa-responsive extrapyramidal syndrome in twins with recessive GTPCH deficiency.

The authors report two twin sisters, age 15 years, with recessive GTP cyclohydrolase deficiency, who presented with neonatal onset of rigidity, tremor, and dystonia but with no other symptoms suggestive of a diffuse CNS involvement. The plasma phenylalanine levels were normal. Treatment with L-dopa/carbidopa, started at age 1 year, was associated with sustained recovery from all neurologic signs. The patients were homozygous for a new recessive mutation in the GHI gene.

Adolescent↗

PubMed2003

[Telementoring in surgery].

Tele-mentoring is an interactive experimental method that allows young surgeons' education by distant learning tutoring of an expert surgeon. The problem about assessment of efficacy and quality of computer-assisted instruction is under evaluation today. Tele-mentoring is supported by videoconferencing system and it is not an exclusive methodology but an additional methodology to traditional didactic for clinicians and surgeons. It allows personal virtual trainings by computers and telecommunication systems. Videoconference allows tutoring for telemedicine, teletriage and telesurgery also.

Education, Distance↗

PubMed2002

Use of mesh to repair the submuscolar pocket in breast reconstruction: a new possible technique.

The reconstruction of the female breast after mastectomy has become a crucial part of primary breast cancer therapy. Setting of an implant is possible only in case of locally abounding soft tissue coverage and when no radiation has before performed. It is necessary a complete integrity of the submuscolar pocket and good blood supply of the skin to avoid failure of the procedure. In Author's experience, started since 1994, an immediate breast reconstruction after mastectomy is performed using gel-silicon implants directly when it was possible or setting first an expander. In six cases the condition of major pectoralis muscle after mastectomy was so foul that an immediate breast reconstruction with prosthesis was not realizable. However, the Authors tried a new technique using polypropylene mesh sutured on the major pectoralis muscle to cover the muscle partially destroyed. Preliminary data from the 6 pts seems to be encouraging.

Adult↗

PubMed2001

Surgery in Italy.

During the past 15 years, surgery in Italy has undergone significant developments in health care services at the teaching and organizational levels. In 1987, the new teaching regulations of medical and surgical schools came into force with the introduction of integrated courses that converge into educational and training areas with precise objectives. For more than a decade, postgraduate schools have had a common guideline throughout the European community--becoming real "residencies." Surgical activity is provided by university hospital facilities and hospitals with a business administration that is completely autonomous as far as organization, income, management, technique, and accounts are concerned. Research guidelines for future developments are mainly addressed toward optimization of organization and use of the most recent technology. The widespread application of day surgery and video-assisted surgery substantiates this evolution of surgery in Italy.

Ambulatory Surgical Procedures↗

PubMed2001

Progressive multifocal leukoencephalopathy in a child with hyperimmunoglobulin E recurrent infection syndrome and review of the literature.

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease due to infection with polyomavirus JC (JCV). PML occurs almost exclusively in immunocompromised patients, and although it has increased markedly in relation to AIDS, remains exceptional in children. We present the case of an immunocompromised child with hyperimmunoglobulin E recurrent infection syndrome (HIES) and pathologically-proven PML. HIES is a rare congenital immunodeficiency that to our knowledge has never before been reported in association with neurological complications. Following a recurrence of bronchopneumonia, the child's motor and cognitive functions deteriorated progressively in parallel with alterations on cerebral MRI. The neurological onset coincided with lymphocyte subset changes. PCR for JCV DNA did not detect the virus in CSF, and brain biopsy was required to secure the diagnosis. Antiviral treatment with cidofovir produced no benefit. Autopsy revealed the typical neuropathological findings of PML which were associated with inflammatory eosinophilic infiltrate (a marker of HIES). In accordance with the few pediatric PML cases reported and here reviewed, the child died five months after neurological onset.

Brain↗

PubMed2000

Clustering data by inhomogeneous chaotic map lattices.

A new approach to clustering, based on the physical properties of inhomogeneous coupled chaotic maps, is presented. A chaotic map is assigned to each data point and short range couplings are introduced. The stationary regime of the system corresponds to a macroscopic attractor independent of the initial conditions. The mutual information between pairs of maps serves to partition the data set in clusters, without prior assumptions about the structure of the underlying distribution of the data. Experiments on simulated and real data sets show the effectiveness of the proposed algorithm.

Journal Article↗

PubMed2000

Life-threatening dystonia-dyskinesias in a child: successful treatment with bilateral pallidal stimulation.

We report a 13-year-old boy who developed severe, refractory dystonia-dyskinesias as an abrupt worsening of a previously nonprogressive movement disorder. The movements became continuous, requiring artificial respiration and continuous sedation in the intensive-care unit. Various drugs and drug combinations failed to achieve control. The child was then treated successfully with bilateral pallidal (GPi) stimulation as shown in the videotape. Four months later and without medication, the boy regained autonomous gait and audible speech; his neurologic condition continues to improve.

Adolescent↗