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Biomedical subjects

Luc Michel

Publications and source records attributed to Luc Michel.

At least 19 recordsLinked to original sources
PubMed2006

Electrodes and multiple electrode systems for radio frequency ablation: a proposal for updated terminology.

OBJECTIVE: Research on technology for soft tissue radio frequency (RF) ablation is ever advancing. A recent proposal to standardize terminology of RF electrodes only deals with the most frequently used commercial electrodes. The aim of this study was to develop a logical, versatile, and unequivocal terminology to describe present and future RF electrodes and multiple electrode systems. MATERIALS AND METHODS: We have carried out a PubMed search for the period from January 1st 1990 to July 1st 2004 in seven languages and contacted the six major companies that produce commercial RF electrodes for use in the liver. In a first step, names have been defined for the five existing basic designs of single-shaft electrode. These names had to be unequivocal, descriptive of the electrode's main working principle and as short as possible. In a second step, these basic names have been used as building blocks to describe the single-shaft electrodes in combination designs. In a third step, using the same principles, a logical terminology has been developed for multiple electrode systems, defined as the combined use of more than one single-shaft RF electrode. RESULTS: Five basic electrode designs were identified and defined: plain, cooled, expandable, wet, and bipolar electrodes. Combination designs included cooled-wet, expandable-wet, bipolar-wet, bipolar-cooled, bipolar-expandable, and bipolar-cooled-wet electrodes. Multiple electrode systems could be characterized by describing several features: the number of electrodes that were used (dual, triple, etc.), the electric mode (monopolar or bipolar), the activation mode (consecutive, simultaneous or switching), the site of the inserted electrodes (monofocal or multifocal), and the type of single-shaft electrodes that were used. CONCLUSION: In this terminology, the naming ofthe basic electrode designs has been based on objective criteria. The short and unequivocal names of the basic designs can easily be combined to describe current and future combination electrodes. This terminology provides an exact and complete description of the versatile novel multiple electrode systems.

Catheter Ablation↗
PubMed2006

Interrelated overexpression of endothelial and inducible nitric oxide synthases, endothelin-1 and angiogenic factors in human papillary thyroid carcinoma.

OBJECTIVE: Nitric oxide (NO) and endothelin-1 (ET-1) are involved in carcinogenesis. Overexpression of the ET-1 axis has been demonstrated in papillary thyroid carcinoma (PTC). This study investigated the expression of NO synthases (NOS) and their relationship with expression of ET-1 and angiogenic markers in PTC. DESIGN AND PATIENTS: Expression of NOS, angiogenic markers [vascular endothelial growth factor (VEGF), angiopoietin-1 and angiopoietin-2] and their receptors was studied in surgical thyroid samples obtained from 22 patients aged 15-68 years. Three groups were constituted: normal thyroid (n = 5), Hashimoto's thyroiditis (n = 9) and PTC (n = 8). RESULTS: Immunohistochemistry disclosed NOS2 and NOS3 immunoreactivity in PTC cells, the percentage of positive cells being greater than normal (P < 0.02). Real-time quantitative polymerase chain reaction (RTQ-PCR) showed that NOS2 and NOS3 mRNA levels were, respectively, increased (P < 0.02) by 2.6 +/- 0.6 and 4.2 +/- 1.1 times in PTC. RTQ-PCR demonstrated that VEGF, its receptors VEGFR-1 and VEGFR-2, and angiopoietin-2 and its receptor (Tie2) were also overexpressed (P < 0.05) in PTC. Correlations were found between ET-1 expression and that of NOS2, angiopoietin-1 and -2 (P < 0.05). NOS2 mRNA levels also correlated with those of NOS3 and angiopoietin-2 (P < 0.05). In thyroiditis, NOS2 immunoreactivity was observed in inflammatory cells whereas NOS2 mRNA levels were 12.1 +/- 1.6 times higher than normal (P < 0.005). CONCLUSIONS: This study revealed an activation of the NO pathway in thyroid carcinoma, which is interrelated to the ET-1 axis, both systems being overexpressed in concert with angiogenic factors. This global system might play a role in carcinogenesis and constitutes a potential target for anticancer therapy.

Adolescent↗
PubMed2005

Electrodes and multiple electrode systems for radiofrequency ablation: a proposal for updated terminology.

Research on technology for soft tissue radiofrequency (RF) ablation is ever advancing. A recent proposal to standardise terminology of RF electrodes only deals with the most frequently used commercial electrodes. The aim of this study was to develop a logical, versatile and unequivocal terminology to describe present and future RF electrodes and multiple electrode systems. We have carried out a PubMed search for the period from January 1 1990 to July 1 2004 in seven languages and contacted the six major companies that produce commercial RF electrodes for use in clinic. In a first step, names have been defined for the five existing basic designs of single-shaft electrode. These names had to be unequivocal, descriptive of the electrode's main working principle and as short as possible. In a second step, these basic names have been used as building blocks to describe the single-shaft electrodes in combination designs. In a third step, using the same principles, a logical terminology has been developed for multiple electrode systems, defined as the combined use of more than one single-shaft RF electrode. Five basic electrode designs were identified and defined: plain, cooled, expandable, wet and bipolar electrodes. Combination designs included cooled-wet, expandable-wet, bipolar-wet, bipolar-cooled, bipolar-expandable and bipolar-cooled-wet electrodes. Multiple electrode systems could be characterised by describing several features: the number of electrodes that were used (dual, triple, ...), the electric mode (monopolar or bipolar), the activation mode (consecutive, simultaneous or switching), the site of the inserted electrodes (monofocal or multifocal), and the type of single shaft electrodes that were used. In this terminology, the naming of the basic electrode designs has been based on objective criteria. The short and unequivocal names of the basic designs can easily be combined to describe current and future combination electrodes. This terminology provides an exact and complete description of the versatile novel multiple electrode systems.

Catheter Ablation↗
PubMed2005

Local recurrence after hepatic radiofrequency coagulation: multivariate meta-analysis and review of contributing factors.

OBJECTIVE: The purpose of this study was to analyze the factors that influence local recurrence after radiofrequency coagulation of liver tumors. SUMMARY BACKGROUND DATA: Local recurrence rate varies widely between 2% and 60%. Apart from tumor size as an important risk factor for local recurrence, little is known about the impact of other factors. METHODS: An exhaustive literature search was carried out for the period from January 1, 1990 to January 1, 2004. Only series with a minimal follow-up of 6 months and/or mean follow-up of 12 months were included. Univariate and multivariate meta-analyses were carried out. RESULTS: Ninety-five independent series were included, allowing the analysis of the local recurrence rate of 5224 treated liver tumors. In a univariate analysis, tumor-dependent factors with significantly less local recurrences were: smaller size, neuroendocrine metastases, nonsubcapsular location, and location away from large vessels. Physician-dependent favorable factors were: surgical (open or laparoscopic) approach, vascular occlusion, general anesthesia, a 1-cm intentional margin, and a greater physician experience. In a multivariate analysis, significantly less local recurrences were observed for small size (P < 0.001) and a surgical (versus percutaneous) approach (P < 0.001). CONCLUSIONS: Radiofrequency coagulation by laparoscopy or laparotomy results in superior local control, independent of tumor size. The percutaneous route should mainly be reserved for patients who cannot tolerate a laparoscopy or laparotomy. The short-term benefits of less invasiveness for the percutaneous route do not outweigh the longer-term higher risk of local recurrence.

Catheter Ablation↗
PubMed2003

Increased expression of endothelin-1 and its mitogenic receptor ETA in human papillary thyroid carcinoma.

OBJECTIVE: Since the isolation of endothelin-1 (ET-1) in 1988, there has been tremendous interest in the pathophysiological roles of ET-1 as a vasoconstrictive and mitogenic peptide. Whereas ET-1 is mainly released by vascular endothelial cells, it also proved to be produced by various tissues including the thyroid. Because of its mitogenic properties in malignancy and its role as an inflammatory modulator, ET-1 could be involved in thyroid carcinogenesis and thyroiditis. DESIGN AND PATIENTS: Studies were performed in human thyroid samples obtained at the time of surgery from 39 men and women aged 15-72 years. Thyroid samples were classified in four groups according to conventional histology: normal thyroid (n = 7) papillary thyroid carcinoma (n = 12), Hashimoto's thyroiditis (n = 9) and benign nontoxic nodular goitres (n = 11). Immunohistochemistry and real-time quantitative polymerase chain reaction were used to determine the expression of ET-1 and its receptors (ETAR and ETBR). RESULTS: ET-1 and ETAR mRNA levels were, respectively, 3.8 +/- 1.3 and 4.1 +/- 1.5 times greater (P < 0.001) in papillary thyroid carcinoma than in normal thyroid. Expression of ETBR was unaltered. In Hashimoto's thyroiditis, ET-1 and ETAR were also overexpressed (P < 0.005). Furthermore, immunohistochemistry demonstrated a greater percentage of ET-1-positive follicular cells in these conditions (P < 0.001). In nodular goitres, the expression was increased by 1.7 +/- 0.7 times (P < 0.05) but expression of receptors remained unchanged. CONCLUSIONS: ET-1 and ETAR overexpression observed in thyroid carcinoma suggest a mitogenic role of ET-1 that theoretically could be countered by ETAR antagonists. ET-1 and ETAR overexpression in thyroiditis supports a role of ET-1 in the inflammatory process.

Adolescent↗
PubMed2003

[Psychological health of students and identification of persons at risk: avoidance of an exam as symptom of depression].

OBJECTIVE: Our exploratory study concerning student psychological health was aimed at identifying possible subgroups of at-risk students within a college-student population. METHOD: A total of 445 students answered four questionnaires (three standard psychometric instruments and an ad hoc questionnaire comprising 50 multiple-choice questions). We then searched for risk-groups by studying all answers obtained with the ad hoc questionnaire and looking for those answers that were significantly correlated with ratings of psychopathology. To carry out this search, we used first and second order principal components factor analysis. RESULTS: Our results show that the incidence of depression is almost twice as high among students that have withdrawn from an exam session than among the other students in our sample. It is further possible to determine that, in our sample, it is not withdrawing from an exam session that causes depression but, rather, it is depression that increases the probability of withdrawing from an exam session. CONCLUSION: It thus definitely seems that, unlike flunking exams, withdrawing from exams is often a symptom of depression.

Adult↗
PubMed2002

Intraoperative gamma probe detection of insulinoma in an elderly patient with pancreatic cystic lesions.

Insulinoma is a rare endocrine tumour in the elderly. We report the case of an 81-year-old woman suffering from grand mal seizures. Insulinoma was suspected because plasma glucose and insulin levels were 1.5 mmol/l and 80.4 pmol/l, respectively. A pancreatic computerized tomography (CT) scan, magnetic resonance imaging (MRI) and arteriography were normal but (111)In-DTPA-octreotide scintigraphy detected a hotspot in the pancreatic tail. Intraoperative pancreatic ultrasonography and palpation were non-contributory due to multiple pancreatic cysts and nodular lesions. However, a gamma-detecting probe localized a small tumour, labelled preoperatively with (111)In-DTPA-octreotide. Intraoperative insulin measurements in portal venous blood confirmed the successful removal of an insulinoma that was 6 mm in diameter histologically. Pancreatic cystic lesions increase with age and make the intraoperative localization of the insulinoma difficult. Intraoperative gamma probe detection of the tumour labelled with (111)In-DTPA-octreotide might therefore constitute a useful surgical tool.

Aged↗
PubMed2002

The protection of the patient's private life: a vast normative landscape. First Part.

The debate on the protection of people's private life is stronger than ever, particularly in the health care sector, where choices have to be made in order to decide between the conflicting interests at stake. This Article gives an overview of the general provisions that aim, for the time being, at guaranteeing this protection to the patient. His or her right to respect for private life, which aims at protecting not only the confidentiality of his or her private realm and relationships with others, but also his or her freedom of choice regarding this private realm and these relationships, is indeed expressed, in various forms, in a large number of texts of every possible origin. It would be a mistake to regard these as a heap of redundant rules. These texts can be distinguished according to their content, the time of their elaboration and their authors. Although complex, the normative structure that they form is not void of effectiveness. A next article will examine how they are extended and supplemented by provisions trying to answer, at the level of the respect of private life, to the growing use of computers in medical practice.

Belgium↗
PubMed2002

The protection of the patient's private life: the computer challenge. Second part.

Today, medical practice is invaded by a growing number of technologies of all kinds, among which computer techniques have an important place. Although they have significant advantages, for instance in terms of medical record management, they give rise to several problems, particularly concerning the confidentiality of the patient's data with regards to third party. A great number of specific provisions, complementary to the general texts protecting private life (examined in the first part of this two parts article), endeavour to solve these problems. It is true that these provisions are recent, have various origins and often appear as rules difficult to understand. Yet, they are partially inspired by a common logic. Relying on these common features, the authors make two suggestions for the future, in order to avoid that the growing computerisation of medical practice eventually destabilises the health care relationship: a) Any dictatorship of confidentiality must be rejected b) Stimulating a sense of professionalism is most likely the way to avoid an anarchic and unrealistic development of rules aimed at regulating the health care relationship.

Computers↗
PubMedDate not supplied

The protection of the patient's private life: a vast normative landscape. First part.

The debate on the protection of people's private life is stronger than ever, particularly in the health care sector, where choices have to be made in order to decide between the conflicting interests at stake. This Article gives an overview of the general provisions that aim, for the time being, at guaranteeing this protection to the patient. His or her right to respect for private life, which aims at protecting not only the confidentiality of his or her private realm and relationships with others, but also his or her freedom of choice regarding this private realm and these relationships, is indeed expressed, in various forms, in a large number of texts of every possible origin. It would be a mistake to regard these as a heap of redundant rules. These texts can be distinguished according to their content, the time of their elaboration and their authors. Although complex, the normative structure that they form is not void of effectiveness. A next article will examine how they are extended and supplemented by provisions trying to answer, at the level of the respect of private life, to the growing use of computers in medical practice.

Confidentiality↗
PubMedDate not supplied

The protection of the patient's private life: the computer challenge. Second part.

Today, medical practice is invaded by a growing number of technologies of all kinds, among which computer techniques have an important place. Although they have significant advantages, for instance in terms of medical record management, they give rise to several problems, particularly concerning the confidentiality of the patient's data with regards to third party. A great number of specific provisions, complementary to the general texts protecting private life (examined in the first part of this two parts article), endeavour to solve these problems. It is true that these provisions are recent, have various origins and often appear as rules difficult to understand. Yet, they are partially inspired by a common logic. Relying on these common features, the authors make two suggestions for the future, in order to avoid that the growing computerisation of medical practice eventually destabilises the health care relationship: a) Any dictatorship of confidentiality must be rejected. b) Stimulating a sense of professionalism is most likely the way to avoid an anarchic and unrealistic development of rules aimed at regulating the health care relationship.

Confidentiality↗