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Biomedical subjects

A Bizzi

Publications and source records attributed to A Bizzi.

At least 19 recordsLinked to original sources
PubMed2007

Bio-image warehouse system: concept and implementation of a diagnosis-based data warehouse for advanced imaging modalities in neuroradiology.

Advanced neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), chemical shift spectroscopy imaging (CSI), diffusion tensor imaging (DTI), and perfusion-weighted imaging (PWI) create novel challenges in terms of data storage and management: huge amounts of raw data are generated, the results of analysis may depend on the software and settings that have been used, and most often intermediate files are inherently not compliant with the current DICOM (digital imaging and communication in medicine) standard, as they contain multidimensional complex and tensor arrays and various other types of data structures. A software architecture, referred to as Bio-Image Warehouse System (BIWS), which can be used alongside a radiology information system/picture archiving and communication system (RIS/PACS) system to store neuroimaging data for research purposes, is presented. The system architecture is conceived with the purpose of enabling to query by diagnosis according to a predefined two-layered classification taxonomy. The operational impact of the system and the time needed to get acquainted with the web-based interface and with the taxonomy are found to be limited. The development of modules enabling automated creation of statistical templates is proposed.

Diagnostic Imaging↗
PubMed2006

GJA12 mutations in children with recessive hypomyelinating leukoencephalopathy.

BACKGROUND: Pelizaeus-Merzbacher-like disease (PMLD) is an inherited hypomyelinating leukoencephalopathy with onset in early infancy. Like Pelizaeus-Merzbacher disease (PMD), PMLD is characterized clinically by nystagmus, cerebellar ataxia, and spasticity, due to a permanent lack of myelin deposition in the brain. Mutations in the GJA12 gene, encoding connexin 47 (Cx47), were recently reported in five children with autosomal recessive PMLD. OBJECTIVES: To evaluate the impact of mutations in the GJA12 gene in, and define the clinical and neuroimaging features of, autosomal recessive PMLD. RESULTS: The authors screened for GJA12 mutations in 10 additional PMLD families originating from Italy, Pakistan, and Saudi Arabia. Three novel homozygous GJA12 mutations were identified in 12 mutant cases distributed in 3 of 10 families. The mutations segregated with the disease according to an autosomal recessive trait and included one missense (G236S) and two nonsense (L281fs285X and P131fs144X) changes. CONCLUSIONS: The identification of homozygous mutations predicting the synthesis of aberrant and truncated polypeptides, and their tight segregation with the disease in very large families, clearly demonstrate that the loss of Cx47 function is the cause of the disease. The phenotype of GJA12-related Pelizaeus-Merzbacher-like disease is fairly homogeneous and similar to that of Pelizaeus-Merzbacher disease. However, slower progression of symptoms, greater preservation of cognitive functions, and partial myelination of corticospinal tracts at MRI were distinctive features, which could help in the differential diagnosis.

Adolescent↗
PubMed2004

A family with Alzheimer disease and strokes associated with A713T mutation of the APP gene.

Three members of an Italian family with autosomal dominant dementia and multiple strokes had the A713T mutation of the APP gene. The neuropathologic examination of the proband disclosed Alzheimer disease (AD) with severe cerebral amyloid angiopathy and multiple infarcts. This indicates that the A713T mutation of the APP gene, lying at the gamma-secretase cleavage site, can be responsible for AD with symptomatic cerebral amyloid angiopathy.

Alzheimer Disease↗
PubMed2003

Consciousness disturbances in megalencephalic leukoencephalopathy with subcortical cysts.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a genetic disorder featuring diffuse MRI white matter abnormalities and a discrepantly mild clinical picture. It is related to different mutations in MLC1 gene encoding a putative membrane protein of still unknown function. We report on a genetically proven MLC patient who presented with a peculiar clinical course characterized by a prolonged comatose state following a minor head trauma at 12 years of age. The disturbance of consciousness lasted for over four months and then gradually improved. Proton MR spectroscopic imaging studies showed a moderately severe depletion of N-acetylaspartate restricted to the white matter with sparing of the cortical grey matter. The full recovery from coma suggests a transitory functional impairment of the structures implicated in the maintenance of consciousness.

Brain Diseases↗
PubMed2002

Cerebral white matter involvement in children with mitochondrial encephalopathies.

In childhood mitochondrial encephalopathies the common MRI features are bilateral symmetric abnormalities in basal nuclei and brainstem. The presence of diffuse white matter abnormality has been described only in a few cases. Among a series of 110 children with mitochondrial encephalopathies, 8 patients with MR imaging consistent with a leukoencephalopathy were retrospectively evaluated. Diagnosis was based on the recognition of the biochemical defect in muscle homogenate. H-MR spectroscopic imaging was performed in six of them. Biochemical analysis demonstrated a defect of respiratory chain complexes in six patients: complex I in two cases, complex II in two, complex IV in one, multiple complexes defect in one. Pyruvate dehydrogenase deficiency was demonstrated in two patients. MRI showed severe involvement of the brain white matter without significant basal nuclei or brainstem abnormalities. Two patients developed large cystic areas since onset; in two others progressive vacuolisation of affected white matter was seen later in the course of the disease. One patient with pyruvate dehydrogenase deficiency also presented with a diffuse cortical polymicrogyria. H-MR spectroscopic imaging showed a decrease of N-acetylaspartate, choline and creatine with lactate accumulation in five patients, and was normal in one. These findings suggest that mitochondrial disorders should be included in the differential diagnosis of white matter disorders.

Atrophy↗
PubMed2000

Brainstem encephalitis resulting from Epstein-Barr virus mimicking an infiltrating tumor in a child.

A case of a child with subacute neurologic features and imaging findings consistent with a brainstem encephalitis that was discovered to be related to a primary central nervous system infection caused by Epstein-Barr virus is presented. A brainstem tumor was initially suspected, but a correct diagnosis was formulated on the basis of the favorable clinical course and the detection of positive Epstein-Barr virus serology. In contrast to a prompt recovery of neurologic signs the neuroimaging alterations persisted for a longer time. The present report emphasizes the possible role of Epstein-Barr virus in the pathogenesis of infectious neurologic disorders in childhood, underlining the unusual presentation of a brainstem encephalitis, and considers the discrepancy between the course of neurologic features and the evolution of imaging alterations.

Antibodies, Viral↗
PubMed2000

MR imaging and proton MR spectroscopy in adult Krabbe disease.

We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.

Adult↗
PubMed1997

Sexual behavior and hemispheric laterality of the focus in patients with temporal lobe epilepsy.

Various studies have described an unusually common incidence of sexual and reproductive dysfunction in patients affected by temporal lobe epilepsy (TLE). The purpose of the present study was to further investigate, by means of an ad hoc questionnaire, the relationship between sexual disorders and the hemispheric laterality of the epileptic focus in men and women with right (R) TLE and left (L) TLE. The results suggest a reduction of sexual interest in patients with R-TLE as compared with L-TLE in both men and women. This effect was fundamentally observed when sexual interest was implicitly explored. No significant difference was found between R-TLE and L-TLE groups concerning most aspects of sexual performance. Various hypotheses are discussed to interpret this effect of hemispheric lateralization on sexual interest.

Adult↗
PubMed1996

Imaging focal reperfusion injury following global ischemia with diffusion-weighted magnetic resonance imaging and 1H-magnetic resonance spectroscopy.

The purpose of the study was to determine whether diffusion-weighted magnetic resonance imaging (DWI) could identify focal lesions that develop in ischemia-sensitive cerebral tissues during reperfusion following global brain ischemia. Localized 1H-Magnetic Resonance Spectroscopy (1H-MRS) measurements were also obtained to determine whether abnormal spectroscopic markers were associated with focal lesions and to define time correlations between DWI and metabolic changes. Brain diffusion-weighted magnetic resonance imaging measurements were made in a cat model of repetitive global cerebral ischemia and reperfusion. Five animals were exposed to three episodes of 10 min vascular occlusions at hourly intervals. Three animals were evaluated as controls. DWI, T2WI, and 1H-MRS data were acquired for up to 12 h. Transient focal DWI hyperintensity was detected in the hippocampus, basal ganglia, and cortical watershed areas. These focal abnormalities usually appeared during the final reperfusion and eventually spread to encompass all of the gray matter. Spectroscopic measurements demonstrated the expected elevation of the lactate signal intensity during vessel occlusion, which returned to normal during early reperfusion. A subsequent rise in the lactate signal occurred approximately 3-4 h after the beginning of the third reperfusion. This late lactate elevation occurred after focal hyperintensities were identified by DWI. No significant signal changes were seen in spectroscopic metabolites other than lactate. The study illustrates that DWI and 1H-MRS are sensitive to focal cerebral lesions that occur during reperfusion following global cerebral ischemia.

Animals↗
PubMed1996

Pontine lesions in idiopathic narcolepsy.

Three patients had longstanding (37 to 50 years), highly disabling narcolepsy, poorly controlled by treatment. The clinical histories were typical, consisting of sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, disturbed nocturnal sleep, and HLA-DR2 tissue typing. Polygraphic findings confirmed the diagnosis. Neurologic examination, spinal fluid, and evoked potentials were normal. On MRI scanning, all three patients showed overlapping bilateral and symmetric brainstem T2 hyperintensities circumscribed to the ventrolateral aspect of the midrostral pons. The nature of the lesions remains uncertain but their location corresponded to the pontine oral reticular formation, where the neuronal network generating REM sleep is located. This is the first report of MR signal abnormalities in patients with idiopathic narcolepsy and suggests a causal relationship between the disease and the central pontine lesions.

Aged↗
PubMed1995

Cerebral white matter in the centrum semiovale exhibits a larger N-acetyl signal than does gray matter in long echo time 1H-magnetic resonance spectroscopic imaging.

Long echo time (272 ms) 1H magnetic resonance spectroscopic imaging was used to measure the relative magnitudes of the N-acetylaspartate (NAA) signal in a variety of anatomically defined brain structures (centrum semiovale, thalamus, medial frontal cortex, and genu of the corpus callosum) composed primarily of gray matter or white matter. Six normal young adult humans aged 30-40 were studied. With a 95% level of statistical confidence, the white matter in the centrum semiovale (CSO) produced a more intense NAA signal than did the gray matter in the thalamus and the frontal cortex. Differences between the white matter regions were also noted. The CSO white matter's NAA signal yielded a larger NAA signal than did the white matter of the genu of the corpus callosum. Possible reasons for the anatomical variation in the cerebral NAA signal intensity are discussed.

Adult↗
PubMed1995

Response of non-Hodgkin lymphoma to radiation therapy: early and long-term assessment with H-1 MR spectroscopic imaging.

PURPOSE: To determine whether proton magnetic resonance (MR) spectroscopic imaging is a sensitive technique for defining tumor extent and assessing response of cerebral lymphoma to therapy. MATERIALS AND METHODS: Four hydrogen-1 MR spectroscopic imaging studies were performed in a patient with non-Hodgkin lymphoma (NHL) before, during, and after radiation therapy and at follow-up at 33 months after diagnosis of the recurrence of disease. The patient had a single, large lesion in the brain and underwent hyperfractionated radiation therapy for 4 weeks. A series of MR images was also obtained. RESULTS: The pretreatment study showed a lesion with a distinct spectral pattern: marked elevation of choline and lipids and great reduction of creatine and N-acetylaspartate. During and after treatment, H-1 MR spectroscopic images depicted a progressive reduction of the abnormal choline and lipid signals. Thirty-three months after treatment, multiple-section H-1 MR spectroscopic images showed normal spectral patterns in all sections examined. CONCLUSION: H-1 MR spectroscopy may contribute to the neuroradiologic evaluation of NHL and, in particular, may be useful in monitoring therapeutic response.

Aspartic Acid↗
PubMed1992

Progress report on the anorexia induced by drugs believed to mimic some of the effects of serotonin on the central nervous system.

Some agents that increase serotoninergic transmission in the brain show anorectic activity at doses that do not interfere with the behavior of rats and other animal species. These agents reduce food intake by a mechanism that clearly differs from that involved in the anorectic activity of d-amphetamine. d-Fenfluramine, fluoxetine, and sertraline are three drugs that have already been tested and are used in man. These compounds accumulate in the brain and are metabolized through N-dealkylation. They affect the uptake and release of serotonin at different concentrations, with mechanisms that do not completely overlap. There is pharmacological evidence that d-fenfluramine and sertraline exert their anorectic activity by enhancing the stimulation of 5-HT1nonA receptors whereas fluoxetine seems to affect at anorectic doses both serotoninergic and dopaminergic systems. The role of serotonin in controlling food intake will be discussed, and the effects of agents that reduce serotoninergic transmission will also be considered.

Animals↗
PubMed1992

Anorectic activity of fluoxetine and norfluoxetine in rats: relationship between brain concentrations and in-vitro potencies on monoaminergic mechanisms.

The present study was aimed at establishing the importance of brain monoamine uptake and release mechanisms in the anorectic activity of fluoxetine, relating them to the actual brain concentrations of the parent drug and its metabolite norfluoxetine after anorectic doses in rats. Both compounds showed anorectic activity when administered intraperitoneally, norfluoxetine being slightly more active (ED50 = 22.9 mumol kg-1) than fluoxetine (ED50 = 35.0 mumol kg-1) despite the fact that the metabolite is about ten times less potent than the parent drug in inhibiting 5-hydroxytryptamine (5-HT) uptake. Comparing the brain concentrations of norfluoxetine, in terms of maximum concentrations (Cmax) and area under the curve (AUC), after the ED50 of fluoxetine or synthetic norfluoxetine, it also appeared that the metabolite plays a major role in the anorectic effect of the parent drug in rats. Brain Cmax of fluoxetine (48.7 microM) and norfluoxetine (21.7 and 27.3 microM after metabolite and drug, respectively) were several times those blocking 5-HT uptake in-vitro (0.5 microM), making it unlikely that fluoxetine (directly or through its metabolite) reduces food intake by specifically blocking 5-HT neuronal uptake. Brain Cmax of fluoxetine but particularly norfluoxetine were more compatible with those capable in-vitro of affecting catecholaminergic mechanisms, such as inhibition of dopamine and noradrenaline uptake and enhancement of dopamine release. These results together with recent in-vitro findings that the parent compound and its active metabolite induce tritium release from hippocampal synaptosomes previously loaded with [3H]5-HT suggest that mechanisms other than inhibition of 5-HT uptake are involved in the anorectic action of these compounds in rats.

Animals↗
PubMed1992

Anorectic activity of fluoxetine and norfluoxetine in mice, rats and guinea-pigs.

The present study aimed to establish the role of the metabolite norfluoxetine in the anorectic activity of fluoxetine, and to relate the anorectic doses (ED50) to the brain concentrations of the parent drug and its metabolite. Fluoxetine showed anorectic activity at increasing intraperitoneal doses (ED50 = 39.1, 34.7 and 21.7 mumol kg-1 in mouse, rat and guinea-pig, respectively) and norfluoxetine was slightly more active (24.3, 22.9 and 19.1 mumol kg-1, respectively) in all three species. In terms of maximum concentration (Cmax) and area under the curve (AUC) within the experimental period (0-90 min), brain concentrations varied widely and were poorly related to the dose; guinea-pig appeared to be much more sensitive to fluoxetine than was mouse or rat. Administered norfluoxetine was present in the brain of the three species in approximately the same order as fluoxetine, i.e. lower in guinea-pig than in mouse or rat. The Cmax and AUC of norfluoxetine after fluoxetine administration was 50-60% of the values after an equiactive dose of norfluoxetine in mouse and guinea-pig, and more than 80% in rat.

Animals↗
PubMed1992

Mapping of brain tumor metabolites with proton MR spectroscopic imaging: clinical relevance.

Brain tumor metabolism was studied with hydrogen-1 magnetic resonance spectroscopy and positron emission tomography with fluorine-18 fluorodeoxyglucose in 50 patients. N-acetylaspartate (NAA) was generally decreased in tumors and radiation necrosis but was somewhat preserved at neoplasm margins. Choline was increased in most solid tumors. Solid high-grade gliomas had higher normalized choline values than did solid low-grade gliomas (P < .02), but the normalized choline value was not a discriminator of tumor grade, since necrotic high-grade lesions had reduced choline values. Serial studies in one case showed an increase in choline as the glioma underwent malignant degeneration. Choline values were lower in chronic radiation necrosis than in solid anaplastic tumors (P < .001). In two cases studied before and after treatment, clinical improvement and a reduction in choline followed therapy. Lactate is more likely to be found in high-grade gliomas, but its presence is not a reliable indicator of malignancy.

Adolescent↗
PubMed1992

Progress report on the anorectic effects of dexfenfluramine, fluoxetine and sertraline.

This progress report on the anorectic effect of serotoninergic indirect antagonists compares the action of D-fenfluramine, fluoxetine and sertraline and their N-dealkylated metabolites. Brain levels of drugs and their metabolites were measured after equi-active anorectic doses. Fluoxetine and sertraline inhibit 5-HT uptake in vitro with a potency which is at least one order of magnitude higher than for D-fenfluramine while all three drugs release 5-HT from synaptosomes and the active concentrations are closer to the brain concentrations reached after anorectic doses. However, a number of differences have been observed between D-fenfluramine and fluoxetine regarding the mechanisms of 5-HT release. Furthermore fluoxetine affected storage of 5-HT in vesicles much more than D-fenfluramine did. The anorectic effect induced by fluoxetine was not antagonized by antiserotoninergic drugs. No evidence of an involvement of CCK in the anorectic effect of D-fenfluramine was found when food intake was determined in rats previously submitted to food deprivation.

1-Naphthylamine↗