Search PubMed⌕ Search

Biomedical subjects

M Desco

Publications and source records attributed to M Desco.

At least 19 recordsLinked to original sources
PubMed2003

Cerebral metabolism and risperidone treatment in schizophrenia.

This paper compares the metabolic changes associated with risperidone treatment in schizophrenia to those induced by haloperidol, as a representative typical neuroleptic. A group of 11 schizophrenic patients of recent onset underwent two [18F] fluoro-desoxi-glucose (FDG)-positron emission tomography (PET) scans at rest: the first one at the moment of the diagnosis, after a minimal treatment with haloperidol followed by wash-out, and the second one after 6 months on risperidone. The study also included 34 patients on chronic haloperidol for comparison. PET images were analyzed using Statistical Parametric Mapping (SPM'99) methods. The only change after treatment with risperidone with respect to the baseline was a slight increase in activity in the primary visual area and the right insula. Patients on chronic haloperidol showed increased activity in the motor cortex and cerebellum, as compared to both minimally treated and risperidone-treated patients. The pattern of metabolic changes induced by risperidone appears to be different from that produced by typical antipsychotics.

Adult↗
PubMed2003

Automatic quantification of viability in epithelial cell cultures by texture analysis.

Quantification of live cells in phase contrast microscopy images allows in vivo assessment of the viability of cultured cells. An automatic screening procedure seems advisable because of the large number of cells that must be counted to achieve reasonable accuracy. This paper presents a method that quantifies necrosis in cell cultures by texture analysis of microscope images. The image is divided into regions of equal size that are classified by means of a segmentation algorithm based on texture analysis into three categories: live cells, necrotic cells and background. The classification uses three discriminant functions, built from parameters derived from the histogram and the co-occurrence matrix and calculated by performing an initial stepwise discriminant analysis on 21 sample images from a training set. The areas occupied by live and necrotic cells and number of live cells have been obtained for primary cellular cultures in intervals of 48 h during 2 weeks. The results have been compared with those obtained by an experienced observer, showing a very good correlation (Pearson's coefficient 0.95, kappa 0.87, N= 1600). A method has been developed that provides an accuracy similar to that provided by an expert, while allowing a much higher number of fields to be counted.

Cell Culture Techniques↗
PubMed2001

P300 amplitude as a possible correlate of frontal degeneration in schizophrenia.

The existence of neurodegeneration is a debated issue in schizophrenia research. The P300 component of event-related electrical potentials (ERP) has been related to the different degree of damage to gray and white matter. This study explores the possible relationship between P300 amplitude and/or latency and the existence of degenerative processes in schizophrenia, by assessing its correlation with volume of sulcal CSF and duration of illness, as transversal indicators of neurodegeneration. Nineteen patients (14 males, 5 females) and 13 controls (6 males, 7 females) were studied with MRI and electrophysiological records (P300). The possible influence of sex and age at the time of the exploration was statistically controlled in both groups. The results show a significant negative correlation between P300 amplitude and prefrontal CSF volume in the patient group. A lower though still significant correlation was also found between P300 amplitude and duration of illness, whereas no correlation was found in the control group. These results support the hypothesis that P300 amplitude may be interpreted as a marker of neurodegeneration in schizophrenia.

Adolescent↗
PubMed2001

Multiresolution analysis in fMRI: sensitivity and specificity in the detection of brain activation.

Multiresolution analysis of fMRI studies using wavelets is a new approach, previously reported to yield higher sensitivity in the detection of activation areas. No data are available, however, in the literature on the analytic approach and wavelet bases that produce optimum results. The present study was undertaken to assess the performance of different wavelet decomposition schemes by making use of a "gold standard," a realistic computer-simulated phantom. As activation areas are then known "a priori," accurate assessments of sensitivity, specificity, ROC curve area and spatial resolution can be obtained. This approach has allowed us to study the effect of different factors: the size of the activation area, activity level, signal-to-noise ratio (SNR), use of pre-smoothing, wavelet base function and order and resolution level depth. Activations were detected by performing t-tests in the wavelet domain and constructing the final image from those coefficients that passed the significance test at a given P-value threshold. In contrast to previously reported data, our simulation study shows that lower wavelet orders and resolution depths should be used to obtain optimum results (in terms of ROC curve area). The Gabor decomposition offers the maximum fidelity in preserving activation area shapes. No major differences were found between other wavelet bases functions. Data pre-smoothing increases ROC area for all but very small activation region sizes.

Algorithms↗
PubMed2000

19. Correlation between FDG PET data and EEG dipole modeling.

Purpose: FDG-PET images and EEG dipole modelling were used to localization of interictal epileptogenic foci. A multimodality approach with the analysis of FDG-PET images, EEG dipoles and anatomical images (MRI) were applied to patients with drug-resistant epilepsy.Methods: Source location was determined using Brain Electromagnetic Source Analysis (BESA) program. The dipole location provided by BESA was then transformed into PET co-ordinates using the patient's MRI previously registered with the PET image. As a difference with other methods, no external markers are necessary.Results: The study group includes ten drug-resistant epileptic patients. FDG hypometabolism was found in all patients. Abnormalities in glucose uptake were always ipsilateral to the EEG dipole. However, quantitative analysis of FDG-PET within hypometabolic areas showed no significant correlation between decrease glucose uptake and location of EEG-dipole source. The comparison of the results using both methods shows that the dipole location matches the FDG-PET hypometabolic area for all the patients. Combining the spatial localization on FDG-PET with the temporal accuracy of EEG dipole source aids in the exact localization of the epileptogenic focus.Conclusion: As a conclusion, the results show that projection of EEG dipole data onto FDG-PET may play a key role in the indication of surgery for the treatment of drug-resistant epileptic patients, provided it is simple and easy to perform.

Journal Article↗
PubMed1999

Regional diastolic function in ischaemic heart disease using pulsed wave Doppler tissue imaging.

AIMS: The aim of this study was to determine the utility of pulsed wave Doppler tissue imaging in the evaluation of regional left ventricular diastolic function in patients with ischaemic heart disease. METHODS AND RESULTS: In 30 normal subjects and 43 patients with ischaemic heart disease, Doppler tissue imaging was performed in each of the 16 segments of the myocardium. The following diastolic pulsed wave Doppler tissue imaging parameters were obtained for each segment: (1) regional early diastolic peak velocity (regional e wave cm.s-1); (2) regional late diastolic peak velocity (regional a wave cm.s-1); (3) regional diastolic e/a velocity ratio; and (4) the regional isovolumic relaxation time, defined as the time interval from the second heart sound to the onset of the diastolic E wave. In patients with ischaemic heart disease, each of these parameters was evaluated and compared in ischaemic and normally perfused segments, based on the presence or absence of obstructive lesions of the supplying coronary artery. In patients with coronary artery disease, several differences were observed between diseased and normal wall segments: the mean segmental peak early diastolic velocity (e wave) was reduced (mean +/- SD: 6.4 +/- 2.1 cm.s-1 vs 8.5 +/- 2.8 cm.s-1; P < 0.01); the e/a diastolic velocity ratio was decreased (0.95 +/- 0.3 vs 1.5 +/- 0.6, respectively; P < 0.01) and the regional isovolumic relaxation time was prolonged (104 +/- 36.7 ms vs 69.6 +/- 30 ms; P < 0.01. No differences were observed in any of these parameters between the normally perfused segments of ischaemic patients and normal subjects. Patients with a normal transmitral diastolic Doppler inflow pattern had a mean of 3.7 +/- 2.7 myocardial segments with a local e/a pulsed wave Doppler tissue imaging velocity ratio < 1, fewer than those with an inverted diastolic transmitral Doppler inflow pattern (10.3 +/- 3 segments; P < 0.001). Overall sensitivity and specificity for an inverted local e/a ratio and a local isovolumetric relaxation time > or = 85 ms were of 62% and 72% and 69% and 80%, respectively. CONCLUSION: Regional diastolic wall motion is impaired at baseline in ischaemic myocardial segments, even when systolic contraction is preserved. Pulsed wave Doppler tissue imaging is a useful non-invasive technique which allows the assessment of regional diastolic performance and dynamics of the left ventricular myocardium. Further studies are required to define this role in the evaluation of coronary heart disease.

Blood Flow Velocity↗
PubMed1998

Isolated kidney controlled perfusion with true physiological pulsatile waveform.

A computer controlled perfusion system has been developed to study the behavior of perfused kidneys in several conditions. The system is designed to perform kidney perfusions at constant pressure and low temperature (about 4 degrees C). We compared 2 types of perfusion pumps, a classical roller pump widely used in hemodialysis circuits and a vacuum powered tubular pump with active valves developed by our group and able to produce a flow pattern very similar to the pulse wave in the human circulatory system. In this preliminary study, we show the hydrodynamics obtained with both pumps in isolated hypothermic kidneys perfused with this system. The different flow patterns with both pumps seem to determine differences in the preservation conditions of the kidney.

Animals↗
PubMed1998

[Integration of multimodal medical images].

Multimodality analysis is becoming a required tool in medical practice due to the development of different image techniques and new imaging processing tools. This paper is a review of the basis of medical image integration, image fusion techniques, and their clinical applications, especially addressing our experience with brain tomographic studies in nuclear medicine and radiology.

Algorithms↗
PubMed1997

Simulated surgery on computed tomography and magnetic resonance images: an aid for intraoperative radiotherapy.

Intraoperative radiotherapy (IORT) is a relatively new technique in which irradiation with electrons is performed during an open surgery procedure. This approach poses significant problems in obtaining accurate dosimetry, since neither the pre- nor the postoperative patient images actually matches the irradiation field. Our objective was to implement a software tool able to provide an estimate of the dose distribution, overcoming the problem of the geometrical mismatch between the images and the surgical field during the irradiation. The program was developed in the C programming language, on a noncommercial version of a Philips EasyVision workstation. The application allows to create a new data set by manipulating the preoperative computed tomography and magnetic resonance images in order to simulate the final geometry of the surgical area during the IORT procedure. The exact dose distribution can then be calculated by transferring these new images to a standard radiotherapy planning system. Also an approximate dose distribution can be quickly displayed by superimposing isodose curves obtained from a water phantom. The proposed approach introduces a helpful tool for dosimetry and planning in IORT protocols, improving their accuracy and safety and allowing for more objective quality control and patient follow-up.

Brain Neoplasms↗
PubMed1997

Postsurgical mediastinitis: a case-control study.

We report the results of a case-control study of postsurgical mediastinitis (PSM) that we conducted from 1985 to 1993. The incidence of PSM was 2.2% (81 of 3,711 cases who underwent sternotomy); we analyzed the findings for 73 cases and 73 controls. Univariate analysis revealed that the risk factors for PSM were emergency surgery (27% of cases vs. 13% of controls), New York Heart Association functional class IV (46.5% vs. 21.9%), heart transplantation (12% vs. 0), and coronary artery bypass graft (CABG) surgery (60% vs. 41%). The incidences of fever, reoperation for bleeding, pacemaker placement, use of vasoactive drugs, prolonged mechanical ventilation, use of central lines, and treatment in the intensive care unit were also higher for cases. Multivariate analysis identified the following independent risk factors for PSM: reoperation (risk ratio [RR], 9.2), need for vasoactive drugs (RR, 3.5), CABG surgery (RR, 3.2), and fever that persisted after the third postsurgical day (RR, 406). The related mortality was 13.7%, and death was significantly more frequent among cases (17.7%) than among controls (2.7%). Multivariate analysis identified the following independent risk factors for mortality: bacteremia (RR, 21.5), the use of an intraaortic balloon (RR, 14.9), advanced age (RR, 1.14 per year), and prolonged mechanical ventilation (RR, 1.1 per day).

Adult↗
PubMed1995

Dissociation between anti-infarct effect and anti-edema effect of ischemic preconditioning.

This study tested the hypothesis that preconditioning, by reducing catabolite accumulation during ischemia, reduces osmotic swelling and myocardial necrosis during subsequent reperfusion. Farm pigs were randomly allocated to one of three groups of treatment: a control group undergoing a 48-min coronary occlusion (CO) of the middle left anterior descending artery, a preconditioned group (2 cycles of 5-min CO and 5-min reperfusion before the 48-min CO), or an intracoronary perfusion group receiving a substrate-free anoxic buffer perfusion into the area at risk between minutes 5 and 10 of the prolonged CO. Animals were killed after 30 min (n = 23) or 6 h (n = 31) of reperfusion. Compared with the control group, both ischemic preconditioning and washout of ischemic by-products by transient anoxic perfusion reduced myocardial edema after 30 min of reperfusion (P < 0.002) by 35 and 32%, respectively, but only ischemic preconditioning reduced final infarct size (by 55%, P < 0.006). Myocardial lactate content before reperfusion, measured in an additional series of 12 experiments, was reduced by 35% in animals receiving preconditioning or intracoronary perfusion. Thus ischemic preconditioning has a marked protective effect against reperfusion edema, and this effect can be explained by reduced catabolite accumulation during ischemia. However, there is no evidence from this study indicating that reduced catabolite accumulation and limited reperfusion edema explain the important anti-infarct effect of ischemic preconditioning.

Animals↗
PubMed1990

Normal biochemistry values in baboons (Papio C. cinocephalus).

1. Analysis of biochemical parameters was carried out on material pooled from 10 baboons, adult male and female, of the Papio c. cinocephalus strain. 2. The values determined were for the common metabolites and enzymes utilized for specific studies in general metabolism (urea, glucose, cholesterol, phospholipids, bilirubin, uric acid, creatinine, alkaline phosphatase, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactic dehydrogenase, leucine amino peptidase, gamma glutamyl transpeptidase, total creatine kinase and amylase). Total protein and its fractions (ratio albumin/globulin, albumin, alpha 1-globulin and alpha 2-globulin) were also determined. 3. Results of these studies were compared with values for normal human adults. 4. The differences obtained between the respective ranges can be explained by the different physiology of the two species and, possibly, may also be caused by the use of human substrates in the enzyme assays. 5. Through the determination of normal values for the baboon, this study provides values for this species as an experimental animal in biomedical research.

Alkaline Phosphatase↗
PubMed1990

Immunological and serological markers predictive of progression to AIDS in a cohort of HIV-infected drug users.

We have performed a prospective 33-month follow-up of the evolution of HIV infection in a cohort of 76 HIV-positive intravenous drug users (IVDUs). We report on immunological and serological variables that proved to be highly predictive of development to AIDS. In a stepwise multivariate analysis of the actuarial progression rate we found the number of CD4+ lymphocytes to be the most powerful predictor of progression to AIDS. We found no independent predictive effects associated with any other variable with predictive power: loss of antibody to p24 antigen, anergy, HIV p24 antigenaemia, loss of antibody to p53 (reverse transcriptase), decreased number of CD8+ T cells, loss of antibody to p31, loss of antibody to p17, beta 2-microglobulin level, loss of antibodies to gp41 and p64, or immunoglobulin A level. We have found that our data differ from those obtained in studies in homosexual men in the different prognostic value of those predictive markers. Our findings should help to identify high risk of progression to clinical AIDS among IVDUs, thereby assisting in the selection of patients for prophylaxis and therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Blood biochemistry values of sheep (Ovis aries ligeriensis).

1. Analysis of biochemical parameters were carried out on material pooled from 30 female sheep (Ovis aries ligeriensis). 2. The values determined were for the common metabolites and enzymes utilized for specific studies in general metabolism (urea, glucose, cholesterol, lipids, bilirubin, uric acid, creatinine, alkaline phosphatase, GOT, GPT, LDH, LAP, CGT, CK and amylase). 3. Results of these studies were compared with values from normal human adults. 4. The differences obtained in human and sheep ranges can be explained by the different physiology of the two species. 5. This study gives values for the sheep as an experimental animal in biomedical research.

Animals↗
PubMed1989

Cell-to-cell interaction: a mechanism to explain wave-front progression of myocardial necrosis.

Histological sections performed 24 h after coronary occlusion in eight pigs displayed compact infarcts extending transmurally with well-defined edges; reconstruction and inspection of the area of necrosis showed a geometric distribution of the infarcts with very irregular, interdigitating edges always in continuity with the main mass of necrosis. Reperfusion in 32 pigs after periods of coronary occlusion of 90, 60, 45, and 30 min exponentially reduced infarct size and transmural extension of the infarct but did not modify its geometry. The two-dimensional size, progression, and geometry of the infarcts could be reproduced by a computer model. In the simulated infarcts, each myocardial cell within the area at risk was represented by a pixel. The algorithm included an inner loop, which determined at random at each iteration a status of reversible or irreversible damage to all pixels. The number of iterations could reproduce infarct of various sizes. With the addition of an index of transmural sensitivity to ischemia, progression of the infarct area could also be reproduced. The only possible means of reproducing the geometry of the infarct was to enter into the program a contiguity condition requiring a direct contact between irreversibly damaged pixels. These observations suggest that the physical interaction between cells is an important determinant of progression of necrosis during coronary occlusion.

Animals↗