Biomedical subjects

Manuel Desco

Publications and source records attributed to Manuel Desco.

27 records · Page 2Linked to original sources

PubMed2003

Anatomical and functional cerebral variables associated with basal symptoms but not risperidone response in minimally treated schizophrenia.

In schizophrenia, structural and functional cerebral variables show an unclear association with clinical features and their value as predictors of response to a typical antipsychotic agents has yet to be determined. The goal of this study was to investigate the relationships between clinical variables (baseline syndromes and response to risperidone) and anatomo-functional brain variables. We studied 19 minimally treated patients with schizophrenia of recent onset using magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) under resting conditions. The following brain variables were studied: volume of the cerebrospinal fluid (CSF) and gray matter (GM) of the dorsolateral prefrontal cortex (DLPFC) and temporal lobe; hippocampal metabolic activity and volume; and metabolic activity of the DLPFC, temporal lobe, putamen and caudate. Anatomical volume measurements were corrected for age and intracranial size using regression parameters determined from a matched sample of control subjects. Using stepwise multiple regression, we assessed the relation between these brain measures and basal scores of symptom dimensions (positive, disorganization, negative and total), as well as their change in response to risperidone. We found that positive and disorganization symptoms improved with risperidone treatment and that hippocampal metabolism, DLPFC CSF volume, and temporal CSF volume predicted baseline symptoms. However, none of the brain measures predicted response to treatment. We conclude that there is evidence of a significant association between basal symptoms and DLPFC atrophy and limbic hyperactivity at rest in recent-onset schizophrenic patients.

Adult↗

PubMed2003

Anatomical and functional brain variables associated with clozapine response in treatment-resistant schizophrenia.

Clozapine alleviates the symptoms of a significant proportion of treatment-resistant schizophrenic patients. Previous studies suggest that the response to clozapine may be associated with prefrontal and temporal anatomy as well as with prefrontal, basal ganglia and thalamic metabolism. A sample of 25 treatment-resistant (TR) schizophrenic patients underwent magnetic resonance imaging (MRI) and 18F-deoxyglucose positron emission tomography (PET) before and after treatment with clozapine. We investigated the association between changes in positive, disorganized, and negative schizophrenic syndromes with clozapine treatment and a set of cerebral variables that included total intracranial volume (ICV); hippocampal, dorsolateral prefrontal (DLPF) and temporal gray-matter volume and metabolism; and metabolic activity of the thalamus, pallidum/putamen, and caudate head. Improvement in positive symptoms with clozapine was directly related to temporal gray-matter volume, whereas improvement of disorganization symptoms was inversely related to ICV and hippocampal volume. Patients with high baseline DLPF cortical volume and metabolic activity were more likely to experience improvement in their negative symptoms. We conclude that clinical improvement with clozapine may be related with the anatomy and metabolic activity of specific brain areas, with the structural integrity of the DLPF and temporal regions showing the maximum predictive capacity.

Adult↗

PubMed2003

Cerebral metabolic patterns in chronic and recent-onset schizophrenia.

This article compares the effects of short- and long-term treatment with haloperidol in schizophrenic patients, with the aim of identifying brain metabolic activity patterns common to acute and chronic patients in spite of their different treatment and illness duration. [18F]fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) studies in the resting condition were performed on 18 healthy controls and two groups of schizophrenic patients: recent onset (RO, n=17) minimally treated with haloperidol, and chronic long-term treated patients (LT, n=34). PET scans were analyzed using statistical parametric mapping (SPM'99) and the P-value threshold to assess differences between groups was validated by bootstrapping techniques. Our results show a distinctive pattern of decreased activation of the visual cortex in RO and LT patients, when compared to healthy controls. Insular hypometabolism and a certain degree of hypofrontality were observed in the LT group when compared to RO patients. The main effect of the long-term administration of haloperidol seems to be an increase of cerebellar, basal ganglia and motor area metabolism.

Acute Disease↗

PubMed2003

New techniques for the assessment of regional left ventricular wall motion.

The assessment of regional left ventricular (LV) function has been an important yet unresolved problem since the introduction of echocardiography as a diagnostic tool. Abnormal regional LV wall motion is an early finding in multiple cardiac pathologies and its diagnosis is of critical importance. In the last few years diagnostic procedures based on combined use of existing echocardiographic technologies were geared toward improving the accuracy of detection of baseline and/or induced regional wall motion abnormalities. One of the assumptions is that the combination of reduced LV wall thickening and reduced myocardial velocities can be used to accurately diagnose regional myocardial dysfunction. In this article we will discuss several new techniques for the quantification of regional LV function using Doppler echocardiography.

Aging↗

PubMed2002

Association between relative temporal and prefrontal sulcal cerebrospinal fluid and illness duration in schizophrenia.

Changes in sulcal cerebrospinal fluid (CSF) volume have been related to the neurodegeneration hypothesis in schizophrenia. Fifty-three (24 neuroleptic-naive) schizophrenics and a control group (n=26) were studied with MRI to assess regional sulcal CSF values relative to the total volume of brain lobes (prefrontal, orbital, temporal, parietal, and occipital). Segmentation of brain structures was performed using an automatic Talairach-based method. Relative CSF volumes were adjusted for age by means of linear regression from normal subjects; the corrected values were used to assess their relationship with illness duration and age of onset (AOS). The volume of sulcal CSF on prefrontal and temporal lobes (bilateral) was significantly greater in schizophrenic patients and showed a significant positive correlation with illness duration not found in the other regions studied. No significant association between CSF volumes and AOS was found in any region. Our findings support the existence of a degenerative process in schizophrenia located in prefrontal and temporal areas.

Adult↗

PubMed2002

Biological dosimetry of magnetic resonance imaging.

PURPOSE: To check the bioeffects of the components of magnetic resonance imaging (MRI). MRI is based on an assumed harmless interaction between certain nuclei in the body when placed in a strong magnetic field and radio wave fields. There are three key factors actuating on the examining body: a powerful static magnetic field (SMF), magnetic gradient fields (MGFs), and pulsed radiofrequency (RF) radiation. MATERIALS AND METHODS: In vitro cells (L-132 cells) were used as biosensors, and different cellular compounds were used as biomarkers (heat shock proteins [HSPs] and their messenger ribonucleic acids [mRNAs], calcium, and adenosine-3',5'-cyclic monophosphate [cAMP]). The biosensors were placed in the bore of a 1.5-T MRI machine and the different electromagnetic fields were operated. RESULTS: HSPs and their mRNAs and cAMP did not respond to SMF, MGFs, or RF radiation. RF radiation increased cytosolic calcium concentration (18%, P < 0.05). CONCLUSION: Although MRI procedures do not induce any cellular stress response, it may cause an unfathomable calcium increase in vitro. Although the in vitro experimental conditions are not totally comparable to clinical situations, the usefulness of the in vivo biological dosimetry, circulating leukocytes as biosensors, and HSPs and/or calcium as biomarkers is suggested.

Calcium↗

PubMed2002

Assessment of normal and ischaemic myocardium by quantitative M-mode tissue Doppler imaging.

This paper presents a methodology and a software package developed to quantify M-mode tissue Doppler imaging (TDI), defining a number of quantitative parameters drawn from velocity and gradient curves obtained after segmenting the myocardial wall into anatomical layers. The independent clinical predictive value of these parameters to detect motion abnormalities in the presence of ischaemia was evaluated in a comparative study between a group of 17 healthy volunteers and 18 ischaemic patients. Factor analysis and stepwise logistic regression were used to assess the independent predictive value of these parameters in detecting abnormal contractility of the basal posterior segment. The statistical analysis performed has proved that any single parameter related to the gradient intensity, particularly the maximum gradient at the moment of the "e" wave, provides meaningful clinical information, achieving a rate of correct classification of 79.1% on the same data set used for the analysis. Adding additional parameters does not improve the diagnostic performance. Further testing with different settings (stress studies, other pathologies or segments) is warranted.

Adult↗

PubMed2002

Intramyocardial analysis of regional systolic and diastolic function in ischemic heart disease with Doppler tissue imaging: role of the different myocardial layers.

BACKGROUND: Preliminary experimental data have shown a nonuniform distribution of myocardial velocities (MVs) across the myocardial wall in normal conditions. However, after ischemic damage to the myocardium, a different pattern of reduction in the myocardial layers has been reported. The aim of this study is to analyze the spatial distribution of MVs and the resultant myocardial velocity gradients (MVGs) during the systolic and diastolic time periods. Doppler tissue imaging (DTI) in color M-mode was used to evaluate 3 different myocardial layers (endocardium, mesocardium, and epicardium) and their changes as a result of ischemia. METHODS: Thirty-two consecutive patients were studied with DTI color M-mode: 18 patients with a history of previous or ongoing myocardial infarction and 14 healthy subjects. Postprocessing of images was accomplished with proprietary software. MV and MVG values of all layers along both systolic and diastolic time were calculated. For temporal analysis, systole was subdivided in 3 equal periods. Early- and late-diastolic times were also identified. RESULTS: In ischemic patients, the mean MV and maximum MV throughout systole decreased significantly in the endocardium and mesocardium, whereas only slightly in the epicardium. The mean MVG was less in ischemic patients (0.66 +/- 0.11 vs 0.23 +/- 0.15, P <.03). Temporal analysis showed a decrease in the maximal MV and MVG in all layers over the 3 systolic periods. This decrease was the more consistent in mesocardium. In diastole, there was a decrease in maximal MV in all layers, being more pronounced in endocardium and mesocardium. Diastolic mean MVG was shown to be different between control and ischemic groups (-0.2 +/- 0.05 vs -0.10 +/- 0.04, P <.06). A significant decrease of the maximal MV in endocardium and mesocardium was reported in the temporal analysis during early diastole. No change was reported in the epicardium. The MVG value also showed a significant decrease (-2.69 +/- 0.29 vs -1.59 +/- 0.89, P <.02). In ischemic patients in late diastole, the maximum MV was increased in all layers of the myocardium, and this increase was observed mainly in the endocardium. An increase in the MVG (-0.78 +/- 0.18 vs -1.47 +/- 0.85, P = NS) was also reported during late diastole. CONCLUSION: There is a nonuniform distribution of velocities in the different myocardial layers under normal conditions. This distribution of velocities undergoes a significant change in patients with ischemic myocardial damage. Intramyocardial wall motion analysis could have clinical applications in both the early detection of ischemia and myocardial viability.

Adolescent↗

PubMedDate not supplied

Multimodal neuroimaging studies and neurodevelopment and neurodegeneration hypotheses of schizophrenia.

The interpretation of the huge number of results in schizophrenia research using neuroimaging is uncertain. However, the simultaneous use of complimentary data obtained with these techniques may yield more relevant information in this regard. In this paper we present a series of studies performed by our group in two schizophrenic samples with the use of structural (magnetic resonance imaging, MRI), functional [glucose positron emission tomography (PET) and N-acetyl-aspartate (NAA) magnetic resonance spectrocopy] and neurophysiological techniques (the P300 event-related potential). Transversal and longitudinal measurements were performed.The integrated vision of the results so obtained allows us to propose the hypothesis of a neurodevelopmentally determined state of prefrontal disinihibition, in which the degree of atrophy would directly relate to the metabolic rate. This state would already be present in the first stages of illness and could have neurotoxic consequences in the long term. This would explain the findings of an association between sulcal cerebrospinal fluid (CSF) and illness duration and decreased NAA levels in chronic but not in recent-onset cases. The prefrotnal disinhibition would overstimulate the limbic system and the hippocampus would become overactivated, the metabolic rate at this level being inversely related to P300 amplitude. Clozapine showed a more selective and intense action on that hyperactive metabolic tone than haloperidol.

Journal Article↗