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Biomedical subjects

M Desco

Publications and source records attributed to M Desco.

32 records · Page 2Linked to original sources
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↗
PubMed1987

Quality assurance in radiation therapy: systematic evaluation of errors during the treatment execution.

A method to control the quality of the radiotherapy treatment during its execution has been developed. The method is based on a wide use of verification films in the practical routine of a centre together with a statistical analysis of the data obtained from them. The stepwise multiple regression analysis is applied in order to assess the influence, on the quality of the treatment, of a set of chosen factors with a certain clinical or technical significance. A test of the method is presented and the results are discussed.

Humans↗
PubMedDate not supplied

[Statistical parametric mapping (SPM) in nuclear medicine].

In the scope of medical research, functional neuroimaging analysis permits the study of pathological or cognitive cerebral processes by using statistical quantification techniques. A tool of increasing use is the SPM (Statistical Parametric Mapping) software due to its wide availability and the variety of statistical studies that can be made. Nevertheless, being unaware of the theoretical background on which it is based may easily lead to inaccurate results and even to the reaching of erroneous conclusions. The present article summarizes these theoretical principles and discusses the main key points of the method without requiring advanced mathematical knowledge.

Data Interpretation, Statistical↗
PubMedDate not supplied

[Technical limitations of the positron emission tomography (PET) for small laboratory animals].

Visualization and quantification of organ function by PET in small laboratory animals is becoming an outstanding tool for characterization of phenotype of transgenic and knock-out animals, for the study of animal models of human diseases, and for the development of new therapeutic drugs and diagnostic biochemical probes. To be able to make use of the PET with small laboratory animals in the same way as it is operated with humans it is necessary to account for the volumetric scale factor as well as for the requirement of maintaining the counting statistics. This work sketches the problems that these requirements represent for the technical design of the scanners and for the execution of the experiments. Finally, some characteristics of commercially available scanners (microPET/ FOCUS, HiDAC, eXplore VISTA, MOSAIC, YAP-(S)PET and rPET) are briefly discussed.

Animals↗