Biomedical subjects

A Boghi

Publications and source records attributed to A Boghi.

6 recordsLinked to original sources

PubMed2006

The effect of gender on planning: An fMRI study using the Tower of London task.

Since the introduction of brain mapping, evidences of functional gender differences have been corroborating previous behavioral and neuropsychological results showing a sex-specific brain organization. We investigated gender differences in brain activation during the performance of the Tower of London (TOL) task which is a standardized test to assess executive functions. Eighteen healthy subjects (9 females and 9 males) underwent fMRI scanning while solving a series of TOL problems with different levels of difficulty. Data were analyzed by modeling both genders and difficulty task load. Task-elicited brain activations comprised a bilateral fronto-parietal network, common to both genders; within this network, females activated more than males in dorsolateral prefrontal cortex (DLPFC) and right parietal cortex, whereas males showed higher activity in precuneus. A prominent parietal activity was found at low level of difficulty while, with heavier task demand, several frontal regions and subcortical structures were recruited. Our results suggest peculiar gender strategies, with males relying more on visuospatial abilities and females on executive processing.

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PubMed2006

Functional MR study of a motor task and the tower of London task at 1.0 T.

INTRODUCTION: The use of functional magnetic resonance imaging (fMRI) for clinical applications and basic neuroscience is constantly increasing. The discussion about minimum performance requirement for a correct implementation of fMRI is still open, and one of the critical points is the magnetic field strength. We tested the feasibility of fMRI at 1.0 T during motor and cognitive tasks. METHODS: Fourteen healthy subjects were scanned during a motor task and 12 while performing the Tower of London task. In the activated areas, the percentage signal change due to BOLD (blood oxygenation level dependent) contrast was analysed. To check basic image quality of the acquisition system we measured quality indices in a temporal series of images of a phantom. RESULTS: Motor and cognitive brain activations matched previous results obtained at higher field strengths. The mean percentage change over subjects in the motor task was in the range 1.3-2.6% for the primary motor area and 0.8-6.7% for the cerebellum. In the cognitive task, the mean percentage change over subjects was 0.7-1.2% for a frontal area and 0.6-2.8% for a parietal area. The percentage noise of the phantom temporal series was less than 0.4%. Percentage changes and signal to noise ratio, although lower than that obtained with high-field systems, allowed activation maps to be obtained in all subjects. CONCLUSION: Our results replicate previous fMRI results demonstrating reproducible motor-related brain activations and extend the field to a complex cognitive task, thus providing evidence of the safety for routine clinical use of 1-T equipment.

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PubMed2003

Progressive multifocal leukoencephalopathy: diffusion-weighted imaging and pathological correlations.

We examined MRI of two patients with progressive multifocal leukoencephalopathy (PML), including diffusion-weighted imaging (DWI), with calculation of apparent diffusion coefficients (ADC). The pathology findings of one patient were compared with those of MRI. The lesions had different ADC and DWI appearances, depending on the stage of the disease. Newer lesions and the advancing edge of large lesions had normal-to-low ADC and gave high signal on DWI. Older lesions and the centre of large lesions had increased ADC and gave low signal. High signal on DWI and low ADC mark the regions of active infection and cell swelling, distinguishing them from areas of reparative gliosis.

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PubMed2002

Abnormal ubiquitination of axons in normally myelinated white matter in multiple sclerosis brain.

The hallmark of the lesions in multiple sclerosis (MS) is inflammatory demyelination with sparing of axons. Recent neuropathological and neuroradiological investigations show that structural changes of the axons occur, both in plaques and in the normal appearing white matter. A better understanding of the axonal damage in MS is important, since this may be responsible for permanent disability. We have investigated the immunoreactivity for ubiquitin, a sensitive method to detect axonal dystrophy and accumulation of abnormal proteins in pathological conditions of the nervous system, in the brains of six cases of MS (age range 39-66 years). Tissue blocks were fixed in formalin and embedded in paraffin. A panel of antibodies was used: anti-ubiquitin, anti-neurofilament (SMI-31 + SMI-32), anti-amyloid precursor protein and anti-PGP9.5. We focused our attention on chronic plaques, recognized by the absence of Luxol Fast Blue B-positive inclusions in macrophages. SMI-31 + SMI-32 showed the presence of a variable amount of axons within the plaques; the axonal network within the plaques was looser than outside. No ubiquitin reactivity was present in chronic plaques. In the normally myelinated white matter surrounding the plaques, a dense granular ubiquitin immunoreactivity was found both near and far from the plaque edge. No similar staining was found in control brains. Ubiquitination is the first step of a non-lysosomal degradation pathway of proteins. The present findings suggest a derangement of this proteolytic pathway in the axons outside the plaques, possibly as a consequence of chronic absence of myelin in the axonal segment inside the plaque. The spectrum of axonal changes in MS appears to be wider than expected and involves the apparently normal white matter.

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PubMed2000

Cerebral metastases as first symptom of cancer: a clinico-pathologic study.

Symptomatic brain metastases of carcinomas in patients without a previously diagnosed malignancy are frequent in neurosurgical series. Such tumors often lack distinctive morphological characteristics so that the routine histological examination can be unsuccessful in identifying the site of origin. Objectives of the present study were to evaluate the frequency of brain metastases as the only manifestation of an unknown primary cancer by the retrospective analysis of a series of consecutively operated single cerebral metastases; to verify the efficacy of clinical investigations in detecting the site of origin; to investigate whether the primary site can be identified by the immunohistochemical study of the neurosurgical specimens. Antibodies to the following antigens were used: carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19.9, CA 125, BCA-225, cytokeratin 20, PSA, HMB-45. Out of 181 patients operated for single cerebral metastasis of carcinoma, 99 (54.7%) were in patients without any previously diagnosed systemic neoplasm. In 26.7% the primary remained undiagnosed after clinical investigations, in 9 cases even at autopsy. PSA and HMB45 antibodies specifically identified metastases from prostate carcinomas and skin melanomas, respectively. No other specific immunophenotype was identified; the immunoreactivity of the single cases was more or less suggestive for a primary site. Precocious metastases of lung carcinomas expressed CEA more frequently than late metastases. It has been hypothesized that CEA plays some role as a contact mediating device. CEA expression can have some link with the tendency to metastasize precociously to the brain. No major difference of p53 and k-ras expression has been found in precocious versus late brain metastases.

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PubMedDate not supplied

Medulloblastoma with lipidized cells versus lipomatous medulloblastoma.

BACKGROUND: Lipomatous medulloblastoma is a recently identified clinicopathological entity, characterized by areas of lipomatous differentiation, manifestation in adults, and apparently by a favorable prognosis. MATERIAL AND METHODS: In our series of medulloblastomas of adults and children we have found lipidized cells within the tumor in 6 out of 78 cases of adults and in 8 out of 44 cases of children. In 3 adult cases and 3 children cases, lipidized cells were particularly numerous and clustered. RESULTS: Neuronal differentiation was found in 4/6 cases; no case showed GFAP-positive tumor cells. Lipidized cells were constantly immunopositive for vimentin and some of them also for KP-1 and CR3/43. The proliferation potential was evaluated by the immunohistochemical demonstration of MIB-1; MIB-1-labeling index (LI) ranged from 20.8% to 40.5%. No case survived longer than 7 years after diagnosis and postoperative radiotherapy. CONCLUSION: The present 6 cases of heavily lipidized medulloblastoma are not uniform as for age of occurrence, proliferation potential and survival. They do not share the clinical and pathologic features of "lipomatous medulloblastoma". Therefore, the finding of large numbers of lipidized cells in a medulloblastoma does not authorize to diagnose the tumor as "lipomatous medulloblastoma", for which a favorable clinical prognosis is foreseen.

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