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Biomedical subjects

L Viola

Publications and source records attributed to L Viola.

At least 19 recordsLinked to original sources
PubMed2005

Miller-Fisher syndrome mimicking intracranial hypertension following head trauma.

INTRODUCTION: Miller-Fisher syndrome (MFS) is a polyneuropathy with benign outcome characterized by ophthalmoplegia, limb ataxia and tendon areflexia. Impaired consciousness level and intracranial hypertension are very rare symptoms in MFS. CASE REPORT: We describe the case of a 5-year-old girl who showed intracranial hypertension, transient coma and respiratory failure after mild head injury; moreover the patient showed mild ataxia, areflexia, ophthalmoplegia and autonomic disturbances. These symptoms were suggestive of MFS. Electrophysiologic studies and laboratory tests confirmed the diagnosis and immunoglobulins and steroids were given. The child showed a progressive clinical improvement and the final outcome was good. CONCLUSION: This case, initially managed as trauma injury due to the presence of suggestive signs and clinical history, maskered an atypical presentation of Miller-Fisher syndrome, a rare disorder of central nervous system.

Child, Preschool↗
PubMed2004

Hemispherectomy procedures in children: haematological issues.

OBJECTS: In literature, excessive perioperative haemorrhage and related haemodynamic instability have been described as major risk factors in hemispherectomy. In this report we analyse the impact of neurosurgical operation on both the haematological and coagulative patterns of these children, especially focusing on younger patients. METHODS: From 1993 to 2003, 18 consecutive children suffering from intractable epilepsia and treated by hemispherectomy were admitted to the Pediatric Intensive Care Unit (PICU) of Catholic University Medical School, Policlinico Gemelli, Rome. Eight children had an entire hemisphere removed (anatomical hemispherectomy), whereas the remaining 10 underwent disconnective procedures (functional hemispherectomy) or cerebral cortex ablations (e.g. hemicorticectomy). Eleven out of these 18 children underwent hemispherectomy because of hemimegalencephaly (HME): their mean age was 14.5 months (range 3-56 months); non-HME patients underwent surgery for epileptogenic lesions involving the cerebral hemisphere to a great extent or diffusely. Data have been compared with an historical cohort of 13 children operated on before 1992 at the same institution comparable for age, aetiology of epilepsy and the modalities of surgical operation. CONCLUSIONS: Blood losses and haemotransfusions showed a profound influence on the haematologic/coagulative status of the children operated upon. A strict correlation was demonstrated between estimated red cell volume (ERCV) loss and haemostatic impairment in this series. Recent surgical techniques appear to reduce blood losses and related haemocoagulative risks even in younger patients.

Blood Coagulation Disorders↗
PubMed2001

Measurement of the branching ratios of D(+) and D(+)(s) hadronic decays to four-body final states containing a K(S).

We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic.

Journal Article↗
PubMed2001

Experimental realization of noiseless subsystems for quantum information processing.

We demonstrate the protection of one bit of quantum information against all collective noise in three nuclear spins. Because no subspace of states offers this protection, the quantum bit was encoded in a proper noiseless subsystem. We therefore realize a general and efficient method for protecting quantum information. Robustness was verified for a full set of noise operators that do not distinguish the spins. Verification relied on the most complete exploration of engineered decoherence to date. The achieved fidelities show improved information storage for a large, noncommutative set of errors.

Journal Article↗
PubMed2001

Study of the decay D0 --> K+pi-.

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

Journal Article↗
PubMed2001

Intracranial hemorrhage at the onset of thrombotic thrombocytopenic purpura in an infant: therapeutic approach and intensive care management.

Thrombotic thrombocytopenic purpura (TTP) is quite rare in infancy and must be treated intensively as a life-threatening disease. Diffuse vascular thromboses may occur, and neurologic involvement is a cornerstone of the diagnosis of TTP. We describe a case of an infant who presented with a sudden cerebral hemorrhage and subsequently developed the typical clinical features of TTP. Emergency treatment in the Pediatric Intensive Care Unit (PICU) consisted of plasma therapy and exchange-transfusion (EXT) to arrest the intravascular process and the exsanguinating blood loss. Exchange-transfusion is a life-saving procedure that is rarely performed after the neonatal age.

Critical Care↗
PubMed2000

Dynamical generation of noiseless quantum subsystems

We combine dynamical decoupling and universal control methods for open quantum systems with coding procedures. By exploiting a general algebraic approach, we show how appropriate encodings of quantum states result in obtaining universal control over dynamically generated noise-protected subsystems with limited control resources. In particular, we provide a constructive scheme based on two-body Hamiltonians for performing universal quantum computation over large noiseless spaces which can be engineered in the presence of arbitrary linear quantum noise.

Journal Article↗
PubMed2000

Stochastic resonance and nonlinear response using NMR spectroscopy

We revisit the phenomenon of quantum stochastic resonance in the regime of validity of the Bloch equations. We find that a stochastic resonance behavior in the steady-state response of the system is present whenever the noise-induced relaxation dynamics can be characterized via a single relaxation time scale. The picture is validated by a simple nuclear magnetic resonance experiment on water.

Journal Article↗
PubMed2000

Theory of quantum error correction for general noise

A measure of quality of an error-correcting code is the maximum number of errors that it is able to correct. We show that a suitable notion of "number of errors" e makes sense for any quantum or classical system in the presence of arbitrary interactions. Thus, e-error-correcting codes protect information without requiring the usual assumptions of independence. We prove the existence of large codes for both quantum and classical information. By viewing error-correcting codes as subsystems, we relate codes to irreducible representations of operator algebras and show that noiseless subsystems are infinite-distance error-correcting codes.

Journal Article↗
PubMed2000

Preemptive analgesia with tramadol and fentanyl in pediatric neurosurgery.

Preemptive analgesia is based on administration of an analgesic before a painful stimulus generates, so as to prevent the subsequent rebound mechanism. Tissue injury results in disruption of the processing mechanisms of noxious stimuli afferent to the CNS (central nervous system) by way of an increase of inputs in the spinal cord. These reactions may be reduced by the administration of opioids. Few studies on preemptive analgesia with opioids in children are available, and none of them is concerned with pediatric neurosurgery. Tramadol and fentanyl are synthetic opioids which are relatively new and act through the activation of pain-inhibitory mechanisms. We conducted a randomized, prospective trial on the preemptive effects in children of these two analgesic drugs, administered according to three different protocols: tramadol as a bolus (1 mg/kg); tramadol by continuous infusion (150 microg/kg per h); fentanyl by continuous infusion (2 microg/kg per h). In all, 42 children undergoing major neurosurgical operations were enrolled in the study, 14 in each treatment group. Each treatment was started at the induction of general anesthesia and continued throughout the entire duration of the operation. The postoperative pain evaluation was conducted in the Pediatric Intensive Care Unit at the end of the surgical operations and involved comparison of any changes in behavioral (AFS scale and CHEOPS score) and hemodynamic (heart rate, respiratory rate, systolic and diastolic arterial pressure, oxygen saturation, O(2) and CO(2) partial pressure) parameters. Only 2 children, both in group A, needed further drug administration postoperatively. No significant side effects were noticed in any of the three groups, except that in group A there was a higher incidence of nausea and vomiting. Tramadol efficacy seems to be better when it is administered in continuous infusion; this treatment modality also leads to fewer adverse effects. Fentanyl, in contrast, proved to be superior to tramadol in the treatment of postoperative pain. In conclusion, preemptive analgesia is a valid technique for the treatment of acute pain in children undergoing major neurosurgical operations.

Adolescent↗
PubMed2000

Minor head injuries: one year experience according to the new Italian guideline.

BACKGROUND: The data concerning a consecutive series of 4,536 adult patients suffering from minor head injuries treated at the Department of Neurosurgery over a period of one year are reported. METHOD: The patients' age, sex and the circumstances of the injury have been taken into consideration. The patients, according to the new method, were divided into four groups. Group 0 (3,864 patients) included all patients with Glasgow Coma Scale (GCS) score 15. They did not present any clinical features such as loss of consciousness (LOC), post-traumatic amnesia (PTA), headache or vomiting. No risk factors (RF) such as coagulopaties, alcoholism, drug abuse, epilepsy, previous neurological treatment or disabled elderly patients were detected. Group 1 (600 patients) included patients with GCS score 15. The patients presented one or more clinical features (LOC, PTA, headache, vomiting). No RF were presented. Group 2 (24 patients) included patients with GCS score 14 with or without clinical features (LOC, PTA, headache, vomiting) and with or without RF. Group 0-1R (48 patients) included patients with GCS score 15 with or without clinical features (LOC, PTA, headache, vomiting). All of them presented RF. The presence of focal neurological signs, open injury and GCS score < or = 13 were considered criteria for exclusion. FINDINGS: All the patients from groups 1, 0-1R, 2 and 187 patients from group 0 underwent CT scan for a total of 859 exams which are analyzed and discussed. 458 patients were admitted and are divided as follows: 216 from group 0, 192 from group 1, 26 from group 0-1R and all the 24 belonging to group 2. Six patients were treated surgically (3 extradural haematomas, 2 lobe contusions, 1 acute subdural haematoma) and one of them (0.02% of the total) died (extradural haematoma). The patients who were not admitted were sent home with an information sheet after at least a six hour observation period. INTERPRETATION: The authors draw the conclusion that they have evaluated the applicability and efficacy of guidelines, developed by the study group on head injury of the Italian Society of Neurosurgery. A critical part of our guidelines is not only to identify all the intracranial lesions, but to identify patients harbouring relevant intracranial mass before clinical deterioration.

Adolescent↗
PubMed2000

Microwave study of quantum n-disk scattering

We describe a wave-mechanical implementation of classically chaotic n-disk scattering based on thin two-dimensional microwave cavities. Two-, three-, and four-disk scatterings are investigated in detail. The experiments, which are able to probe the stationary Green's function of the system, yield both frequencies and widths of the low-lying quantum resonances. The observed spectra are found to be in good agreement with calculations based on semiclassical periodic orbit theory. Wave-vector autocorrelation functions are analyzed for various scattering geometries, the small wave-vector behavior allowing one to extract the escape rate from the quantum repeller. Quantitative agreement is found with the value predicted from classical scattering theory. For intermediate energies, nonuniversal oscillations are detected in the autocorrelation function, reflecting the presence of periodic orbits.

Journal Article↗
PubMed1999

Familial clustering of Helicobacter pylori infection: population based study.

OBJECTIVES: To assess the rate of intrafamilial transmission of Helicobacter pylori infection in the general population and the role of a family's social background. DESIGN: Population survey. SETTING: Campogalliano, a town in northern Italy with about 5000 residents. PARTICIPANTS: 3289 residents, accounting for 416 families. MAIN OUTCOME MEASURES: Prevalence of H pylori infection assessed by presence of IgG antibodies to H pylori. RESULTS: The overall prevalence of H pylori infection was 58%. Children belonging to families with both parents infected had a significantly higher prevalence of H pylori infection (44%) than children from families with only one (30%) or no parents (21%) infected (P<0.001). Multivariate analyses confirmed that children with both parents positive had double the risk of being infected by H pylori than those from families in which both parents were negative. Family social status was independently related to infection in children, with those from blue collar or farming families showing an increased risk of infection compared with children of white collars workers (odds ratio 2.02, 95% confidence interval 1.16 to 3.49). CONCLUSIONS: H pylori infection clusters within families belonging to the same population. Social status may also be a risk factor. This suggests either a person to person transmission or a common source of exposure for H pylori infection.

Adolescent↗