[THE FOUNDATIONS OF EVIDENCE-BASED MEDICINE]

The fundamentals of Evidence-Based Medicine (EBM) are the clinical experience, the application of best evidences from research and the consideration of patient expectations. It enabled significant progresses in the management of diseases with a low or multifactorial causality. But it has also led to unintended negative consequences, partly related to conflicts of interest. The objective of this article is to bring the attention back to the scientific rigor that must sustain the medical practice, namely in the occurrence : 1) formulating a question that addresses all the elements of an individual clinical situation; 2) exploring the literature systematically; 3) estimating the degree of confidence in the conclusions of clinical trials. EBM provides intuitive tools to address some uncomfortable concepts of biostatistics and to identify the biases and the embellished data that invalidate many studies. However, it is difficult to decide of the care of a single patient from observations issued from the comparison of'heterogeneous groups. Personalized medicine should help to overcome this difficulty and should facilitate clinical decision making by targeting the patients who are most likely to benefit from an intervention without much inconvenience.

[OCEBM levels of evidence system]

The hierarchy of evidence from medical research is a key concept in evidence-based medicine (EBM). In 1998, the Oxford Centre for Evidence-Based Medicine published a levels table based on study designs. An updated and more user-friendly version, published in 2011, focuses on the issues of prevalence, diagnosis, prognosis, treatment and screening. This paper presents and discusses this approach.

Surrogate markers predicting overall survival for lung cancer: ELCWP recommendations

The present systematic review was performed under the auspices of the European Lung Cancer Working Party (ELCWP) in order to determine the role of early intermediate criteria (surrogate markers), instead of survival, in determining treatment efficacy in patients with lung cancer. Initially, the level of evidence for the use of overall survival to evaluate treatment efficacy was reviewed. Nine questions were then formulated by the ELCWP. After reviewing the literature with experts on these questions, it can be concluded that overall survival is still the best criterion for predicting treatment efficacy in lung cancer. Some intermediate criteria can be early predictors, if not surrogates, for survival, despite limitations in their potential application: these include time to progression, progression-free survival, objective response, local control after radiotherapy, downstaging in locally advanced nonsmall cell lung cancer (NSCLC), complete resection and pathological TNM in resected NSCLC, and a few circulating markers. Other criteria assessed in these recommendations are not currently adequate surrogates of survival in lung cancer.

L'endométriose extragénitale

Parietal, appendiceal, pleuropulmonary and diaphragmatic endometriosis represent 5% of endometriosis cases. Diagnosis and management of these extra-genital localisations are described according to the literature. Parietal endometriosis usually requires large resection of the tumor. Appendiceal endometriosis is frequently observed in cases of digestive endometriosis. Induration or rigidity of the appendix due to the presence of deep infiltrating endometriosis justifies appendicectomy. Thoracic and diaphragmatic endometriosis is characterized by the presence of typical symptoms during the perimenstrual periode. Medical treatment obtaining therapeutic amenorrhea is firstly administered and surgery is indicated in cases of symptoms recurrence.

[Recommendations for writing patient information statements]

With Evidence-Based Medicine, shared decision making is attracting considerable interest as a means by which patient preferences can be incorporated into clinical decisions. Patients cannot express informed preferences unless they are given sufficient and appropriate information, including a detailed explanation concerning their condition, the different therapeutic options and the likely outcomes with and without treatment. A patient education leaflet is a potentially powerful tool for communicating information to patients, who will be able to participate in the process of decision making. The present article is a review of available guides for the writing of patient information materials. It also includes criteria for evaluating their quality.

[The IGF system: summary and recent data]

We are entitled to state that our knowledge about the IGF system has literally exploded in the last years. Having been considered for some time merely as trophic and mitogenic factors, the IGFs now appear as molecules essential for the differentiation of many cell types, and even more so, as powerful protective agents for the nervous and the cardiovascular systems. However, these properties so beneficial in normal physiological conditions, are subverted by the cancerous cells who use them to extend their life span and resist therapy. The IGFs did not live up to expectations in the treatment of diabetes; however, today their capacity to improve the condition of patients suffering from severe neurological, renal or muscle diseases is tested. The IGF system might also be targetted by the anticancer treatments. In the following paper we have briefly summarized our knowledge on the IGF system, and presented in more detail the recent data.

[How to practically solve diagnostic or therapeutic problems in an EMB process?]

Evidence-Based Medicine (EBM) can be defined as the use of best current evidence from clinical research in making decisions about the care of individual patients. It consists of a process of turning clinical problems into questions and then locating the best available evidence to answer them, critically appraising the evidence for its validity and usefulness, and applying the findings to clinical practice. The present article presents the EBM principles and their application to diagnostic and therapeutic questions. Further detailed information on Evidence-Based Medicine is presented at the URL address: http:¿www.ebm.lib.ulg.ac.be/prostate/ebm.+ ++htm.

[Problem-based learning, description of a pedagogical method leading to evidence-based medicine]

Problem-Based Learning is an educational method which uses health care scenarios to provide a context for learning and to elaborate knowledge through discussion. Additional expectations are to stimulate critical thinking and problem-solving skills, and to develop clinical reasoning taking into account the patient's psychosocial environment and preferences, the economic requirements as well as the best evidence from biomedical research. Appearing at the end of the 60's, it has been adopted by 10% of medical schools world-wide. PBL follows the same rules as Evidence-Based Medicine but is student-centered and provides the information-seeking skills necessary for self-directed life long learning. In this short article, we review the theoretical basis and process of PBL, emphasizing the teacher-student relationship and discussing the suggested advantages and disadvantages of this curriculum. Students in PBL programs make greater use of self-selected references and online searching. From this point of view, PBL strengthens the role of health libraries in medical education, and prepares the future physician for Evidence-Based Medicine.

[Selection of EBM resources on the internet]

To integrate Evidence-Based Medicine (EBM) into practice, the physician has access to a number of resources on the Internet. They belong to two distinct groups: tools intended for EBM learning and EBM syntheses prepared by different international organizations. The present article presents the main EBM resources on the network and comments on them. These information are also available on the URL site: http:www.ebm.lib.ulg.ac.be/prostate/link_ebm .htm.

[Pancreatic adenocarcinoma: role of pathologic anatomy]

Duct cell adenocarcinoma is by far the most frequent neoplasm of the pancreas, accounting for about 80% of malignant tumors. In this report, we describe the main diagnostic pitfalls of this cancer in routine or frozen sections, as well as the help of immunohistology to make the differential diagnosis. We also discuss the potential interest of tumor markers for evaluating the prognosis of these tumors and provide information about the creation of a Web site (URL: http://www.ebm.lib.ulg.ac.be/index.htm) created to help clinicians exploit the laboratory results.

[Prognostic evaluation of human solid tumors by immunohistology]

The aim of this project is to evaluate the interest of new tumor markers in the most frequent solid tumors (breast, colon, prostatic cancers, ...). For each of these tumors, potential prognostic markers have been selected according to the literature and an immunohistologic technique has been developed to analyse them. We will first discuss the role of pathology in oncology, then briefly describe the analyzed markers and finally give information about a Web site (URL: http:/(/)www.ebm. lib.ulg.ac.be/index.htm) created to help clinicians exploit the laboratory results.

A new cis element is involved in the HER2 gene overexpression in human breast cancer cells

The HER2 proto-oncogene product is overexpressed in 30% of breast cancers, and this correlates with poor prognosis. Increased levels of HER2 mRNA in breast cancer cell lines result from increased gene transcription. We report the identification of a new 17-bp-long cis sequence located between positions -506 and -489 from the transcription start site. This sequence is recognized by a trans-activating factor that we tentatively named HER2 transcription factor (HTF). This factor, involved in the increased transcription of the HER2 gene in the BT-474 mammary tumor cells, has a molecular weight of about Mr 50,000. HTF can also bind, but with a lower affinity, to a related cis sequence present in the epidermal growth factor receptor promoter. Interestingly, the HTF binding activity is high in nuclear extracts from several mammary tumor cells overexpressing the HER2 gene.

The 6-kilobase c-erbB2 promoter contains positive and negative regulatory elements functional in human mammary cell lines

A 6-kilobase fragment extending at the 5'-end of the c-erbB2 protooncogene was isolated from a normal human lymphocyte genomic DNA library. The full-length fragment and five subfragments with identical 3'-ends were obtained by progressive unidirectional deletion from the 5'-end and were cloned in front of the luciferase reporter gene. The hybrid genes were analyzed for transcriptional activity in human mammary cell lines synthesizing low (HBL-100 and T-47D), moderate (MDA-MB-453), or high (BT-474) amounts of the c-erbB2 mRNA and were also analyzed in HeLa cells. Gene-specific expression was observed, indicating the presence of multiple cis-acting sequences in the c-erbB2 promoter. A major negative element is located in the -2- to -4-kilobase region. It is flanked on both sides by positive elements that display enhanced transcriptional activity in the BT-474 tumor cells only. While predominant in the low-expressing cells, the effect of the repressor appears to be overcome by the distal transactivator in the high-expressing BT-474 cells, resulting in a 15 to 50 times increase in luciferase activity relative to the HBL-100 and T-47D cells, respectively. Cell-specific expression relies on the trans-acting factors present in the different cell lines. The formation of cell-specific protein-DNA complexes was demonstrated by gel retardation assay.

Expression of the c-erbB2 gene in the BT474 human mammary tumor cell line: measurement of c-erbB2 mRNA half-life

BT474 and SK-BR-3 mammary adenocarcinoma cells contain eight copies of the c-erbB2 gene but overexpress the mRNA 80 times over the levels measured in normal breast or in the HBL-100 cell line. Using Northern blot analysis and molecular titration based on RNAase protection assay, the decrease in the c-erbB2 mRNA level was monitored in BT474 cells treated with actinomycin D from 1 up to 24 h. The c-erbB2 degradation rate during the first 12 h corresponds to a calculated c-erbB2 mRNA half-life of approximately 7 h. Forty percent of the mRNA present in the cells before treatment remains undegraded after transcription has been blocked for 24 h. Pretreatment with cycloheximide results in complete mRNA degradation in 24 h, suggesting that labile proteins stabilize part of the c-erbB2 mRNA population. Comparison with the c-erbB2 mRNA turnover in HBL-100 'normal' cells indicated that the accumulation of the c-erbB2 gene product in the tumor cells is not the result of stabilization of the messenger. Rather, it is correlated with an increased rate of c-erbB2 mRNA transcription as indicated by run-on transcription assays. Both BT474 and SK-BR-3 tumor cell lines were found to synthesize 20-40 times more c-erbB2 mRNA than HBL-100 cells.

Expression of a synthetic gene encoding human insulin-like growth factor I in cultured mouse fibroblasts

A synthetic gene encoding human insulin-like growth factor I (hIGF-I) was assembled and inserted into an expression vector containing the cytomegalovirus immediate early (CMV-IE) transcriptional regulatory region and portions of the bovine growth hormone gene. The recombinant plasmid encodes a 97 amino acid fusion protein containing the first 27 amino acids of the bovine growth hormone precursor and the 70 amino acids of hIGF-I. This plasmid, when transiently introduced into cultured mouse fibroblasts, directs synthesis of the fusion protein, subsequent proteolytic removal of the bovine growth hormone signal peptide, and secretion of hIGF-I into the culture medium. Conditioned medium from transfected cells inhibits binding of 125I-labeled IGF-I to type I IGF receptors on human placental membranes and to acid-stable human serum carrier proteins. The recombinant hIGF-I produced is biologically active, as monitored by the stimulation of DNA synthesis in vascular smooth muscle cells.

A comparison of bovine growth hormone expression directed by bGH genomic or intronless DNA in transiently transfected eukaryotic cells

Two recombinant DNA plasmids were constructed with identical transcriptional and translational regulatory elements controlling expression of the bovine growth hormone (bGH) gene or the bGH gene lacking introns. Transient expression of these plasmids in cultured eukaryotic cells, monitored by assaying secretion of bGH into the culture medium, was employed to examine the relative importance of introns in the expression of this gene. The bGH gene lacking introns is expressed more efficiently than the bGH gene in avian and mammalian cells.

Growth hormone gene expression in eukaryotic cells directed by the Rous sarcoma virus long terminal repeat or cytomegalovirus immediate-early promoter

The cytomegalovirus (CMV) immediate-early (IE) gene-regulatory region was found to be three- to fourfold more efficient than the Rous sarcoma retroviral long terminal repeat (LTR) in promoting expression of the bovine growth hormone (bGH) gene by rat GH3 cells.

Genetic regulation of hepatic steroid 16 alpha-hydroxylase activities in inbred strains of mice

Steroid 16 alpha-hydroxylase activities and properties were studied in C57Bl/6J, 129/J, AKR/R, DBA/2J, C3H/I, and BALB/c mouse liver using four different substrates. The highest enzymatic activities were measured in the female mice, with the exception of the 129/J females. As in the rat liver, the sexual differentiation of the steroid 16 alpha-hydroxylation observed in adult male and female mice took place at puberty. In the adult mouse liver, two steroid 16 alpha-hydroxylase activities (forms I and II) could be differentiated on the basis of their relative affinities for the various steroid substrates and their relative proportions in male and female mouse livers. In the immature mouse liver, no sexual differences could be detected, and the mice of both sexes presented phenotypes identical to those of the adult female. The adult 129/J females appeared genetically deficient with respect to the form I of the steroid 16 alpha-hydroxylase and presented a phenotype identical to that of the adult male mice of the various strains tested. Differences in hydroxylase activities between the C57Bl/6J and 129/J strains were investigated using standard genetic breeding protocols. Steroid 16 alpha-hydroxylase seemed to be inherited additively in the liver of the female mice obtained by crossing the C57Bl/6J male and the 129/J female or the 129/J male and the C57Bl/6J female. In the male mice, regardless of genotype, the observed phenotype was always identical to the two male parental types. Both hormonal and genetic regulations were responsible for the different phenotypes occurring in adult male and female C57Bl/6J and 129/J mouse livers.

Ontogenic development of steroid 16 alpha-hydroxylase as a tool for the study of the multiplicity of cytochrome P-450

1. Activities of progesterone, testosterone, pregnenolone and dehydroepiandrosterone 16 alpha-hydroxylase are undetectable in the fetal rat liver. During the neonatal period, the four enzymic activities increase in parallel to the concentration of cytochrome P-450. Until puberty, they develop similarly in male and female rat livers. From the 40th to the 55th day, the four steroid 16 alpha-hydroxylase activities increase rapidly in the male rat liver. The sexual differentiation of the steroid 16 alpha-hydroxylation observed in adult male and female rats takes place around the 55th day. 2. In the adult rat liver, steroid 16 alpha-hydroxylase is supported by two forms of cytochrome P-450 (form I and form II), which differ in their relative affinities for the various steroid substrates, and by their relative proportions in male and female rat livers. These two forms of cytochrome P-450 are also present in the young male and female rat livers, but are roughly equal in proportion. The transition from the immature to the adult repartition of the two forms occurs during puberty and is correlated with the sexual differentiation of the steroid 16 alpha-hydroxylase activities. 3. During the critical phases of the rat ontogenic development, the in vitro interactions between benzo[a]pyrene and steroids were compared at the level of two rat liver monooxygenases: steroid 16 alpha-hydroxylase and aryl hydrocarbon hydroxylase. (a) In the immature male and female rat livers, progesterone 16 alpha-hydroxylase, and to a lesser extent, pregnenolone 16 alpha-hydroxylase are inhibited by benzo[a]pyrene. Progesterone 16 alpha-hydroxylase is also inhibited by metyrapone. (b) In the young rat, aryl hydrocarbon hydroxylase cannot be inhibited by steroids and appears to be supported by a single form of cytochrome P-450. The transition from the immature to the adult situation occurs around the 40th day.

Competition between benzo[a]pyrene and various steroids for cytochrome P-450-dependent rat liver monooxygenases

Cytochrome P-450-dependent monooxygenases are able to oxidize a large variety of endogenous and exogenous substrates. This paper describes the in vitro interaction between benzopyrene and steroids at the level of two rat liver monooxygenases: steroid-16 alpha-hydroxylase and aryl hydrocarbon hydroxylase (AHH). The results obtained suggest the following conclusions: (1) Steroid-16 alpha-hydroxylase is partially supported by a specific cytochrome P-450 form which is not inhibited in vitro by exogenous substrates. Steroid-16 alpha-hydroxylase is completely independent from cytochrome P1-450 (or P-448), as it is insensitive, in vitro, to alpha-naphthoflavone; (2) AHH is supported by two cytochrome P-450 forms: a specific form which is inducible by methylcholanthrene and inhibited in vitro by alpha-naphthoflavone, but is insensitive to metyrapone and steroids; and another less specific form which is inhibited by metyrapone and steroids in vitro.