High circulating proviral load with oligoclonal expansion of HTLV-1 bearing T cells in HTLV-1 carriers with strongyloidiasis

Adult T cell leukemia (ATLL) develops in 3 - 5% of HTLV-1 carriers after a long period of latency during which a persistent polyclonal expansion of HTLV-1 infected lymphocytes is observed in all individuals. This incubation period is significantly shortened in HTLV-1 carrier with Strongyloides stercoralis (Ss) infection, suggesting that Ss could be a cofactor of ATLL. As an increased T cell proliferation at the asymptomatic stage of HTLV-1 infection could increase the risk of malignant transformation, the effect of Ss infection on infected T lymphocytes was assessed in vivo in HTLV-1 asymptomatic carriers. After real-time quantitative PCR, the mean circulating HTLV-1 proviral load was more than five times higher in HTLV-1 carriers with strongyloidiasis than in HTLV-1+ individuals without Ss infection (P<0.009). This increased proviral load was found to result from the extensive proliferation of a restricted number of infected clones, i.e. from oligoclonal expansion, as evidenced by the semiquantitative amplification of HTLV-1 flanking sequences. The positive effect of Ss on clonal expansion was reversible under effective treatment of strongyloidiasis in one patient with parasitological cure whereas no significant modification of the HTLV-1 replication pattern was observed in an additional case with strongyloidiasis treatment failure. Therefore, Ss stimulates the oligoclonal proliferation of HTLV-1 infected cells in HTLV-1 asymptomatic carriers in vivo. This is thought to account for the shortened period of latency observed in ATLL patients with strongyloidiasis. Oncogene (2000) 19, 4954 - 4960

[Video-laparoscopic diagnosis and follow-up of a peritoneal tuberculosis]

A 21-year-old woman suffering from abdominal pain and a fever of 39 degrees C was hospitalized. Ultrasonography and computed tomographic scan showed a large amount of ascites and one hepatic node. The serum CA 125 level was elevated. Protein Chain Reaction (PCR) searching tuberculosis antigen in ascitic fluid was normal. A diagnosis of peritoneal tuberculosis was supposed and an exploratory laparoscopic procedure performed. Peroperative observation of the ascites, with multiple sites of adhesion, and pathological examination of the hepatic nodule and peritoneum confirmed initial diagnosis. Antituberculous treatment was given for one year. A second laparoscopic procedure was performed and found no disease remaining.

Human herpesvirus 8 transmission from mother to child and between siblings in an endemic population

BACKGROUND

Transmission of human herpesvirus 8 (HHV-8), the aetiological agent of Kaposi's sarcoma, is known to occur during sex among homosexual men. However, other modes of HHV-8 transmission remain to be elucidated in endemic populations.

METHODS

We did a population-based seroepidemiological survey in a village in French Guiana among 1337 individuals of African origin (age 2-91 years) who had reliable genealogical data. Plasma samples were taken and tested for HHV-specific IgG by immunofluorescence assay. Risk factors and familial correlations for HHV-8 seropositivity were modelled by logistic regression analysis by use of the estimating equations approach, which expresses familial dependences in terms of odds ratios. Familial odds ratios were also acquired by use of the distribution of all possible pairs of a given familial dependence.

FINDINGS

The overall HHV-8 seroprevalence was 13.2% with no difference according to sex. HHV-8 seropositivity was strongly age dependent: at 1.2% under 5 years, HHV-8 seroprevalence rose up to a plateau around 15% between 15 and 40 years, and showed a seroprevalence of more than 27% in individuals older than 40 years. Strong familial aggregation in HHV-8 seroprevalence was found with high mother-child (odd ratio 2.8 [95% CI 1.6-5.0]) and sib-sib (3.8 [1.6-9.5]) correlations. By contrast, no significant correlation between spouses (0.6 [0.2-1.9]) was seen.

INTERPRETATION

This pattern of familial aggregation, together with the variation of HHV-8 seroprevalence with age, indicate that, in endemic populations, HHV-8 transmission mainly occurs from mother to child and between siblings during childhood and adolescence.

Detection of a major gene predisposing to human T lymphotropic virus type I infection in children among an endemic population of African origin

Human T lymphotropic virus type I (HTLV-I) is a human oncoretrovirus that causes an adult T cell leukemia/lymphoma and a chronic neuromyelopathy. To investigate whether familial aggregation of HTLV-I infection (as determined by specific seropositive status) could be explained in part by genetic factors, we conducted a large genetic epidemiological survey in an HTLV-I-endemic population of African origin from French Guiana. All of the families in 2 villages were included, representing 83 pedigrees with 1638 subjects, of whom 165 (10.1%) were HTLV-I seropositive. The results of segregation analysis are consistent with the presence of a dominant major gene predisposing to HTLV-I infection, in addition to the expected familial correlations (mother-offspring, spouse-spouse) due to the virus transmission routes. Under this genetic model, approximately 1. 5% of the population is predicted to be highly predisposed to HTLV-I infection, and almost all seropositive children <10 years of age are genetic cases, whereas most HTLV-I seropositive adults are sporadic cases.

[Psychosocial distress and its moderating factors in patients living in precarious socioeconomic conditions consulting in a preventive health and social work center]

BACKGROUND

The effects of a precarious socioeconomic condition on mental health have already been widely described. Nevertheless, sociodemographic, biographical, and mainly psychological determinants of psychosocial distress in these populations are still incompletely known.

METHODS

2315 consecutive subjects, aged 16 to 59, consulting for a free work-up in a preventive health center supported by the National French Health Insurance system, were invited to fill out a series of questionnaires, mainly the GHQ-28 (psychosocial distress), the LOT (dispositional optimism) and the WCCL (coping mechanisms). Socioeconomic and administrative criteria were adopted to define populations living in precarious conditions.

RESULTS

A total of 78.9% complete records could be analyzed: 55% of the studied population constituted the precarious condition group (44.5% males and 55.5% females; mean age 36.2+/-11). This group was characterized by higher psychosocial distress and higher sub-scores of anxiety, social dysfunction and depression, but not somatisation, as well as by increased emotion focused coping and impaired optimism. Globally, GHQ score was positively correlated with emotion focused coping (r=0.36) and negatively with problem focused coping (r=-0.17) and with optimism (r=-0.39). In a multivariate analysis a set of 9 independent variables explained 38% of GHQ-28 total variance: perceived stress, optimism, emotion focused coping, problem focused coping, age, educational degree, precariousness, money problems and parental quarrels during youth. Introducing precariousness in the model constituted of the set of the remaining variables could explain only 2% of additional variance.

CONCLUSION

These results confirm the presence of higher levels of psychosocial distress in subjects living in precarious conditions and underline the moderating role of several psychological variables. They could guide support interventions aimed at helping subjects living in precarious conditions, focused on enhancing their coping resources.

Prognostic and immunohistochemical validation of the capella classification of pancreatic neuroendocrine tumours: an analysis of 82 sporadic cases

AIMS

To study the clinical outcome of 82 cases of pancreatic neuroendocrine tumours classified according to the recent histological and prognostic classification of Capella.

METHODS AND RESULTS

Eighty-two surgical cases of pancreatic neuroendocrine tumours were examined histologically with immunohistochemical staining of paraffin sections using streptavidin-biotin complex and application of antibodies against chromogranin A and 10 hormonal peptides. Classification in four groups correlated with long follow-up and outcome of these cases. Histological examination showed 30 group I, four group II, 41 group III and seven group IV tumours. Twenty-one (70%) of group I tumours were insulinomas, whereas 25% of group III tumours were glucagonomas and 25% were unclassified. Most group IV tumours were unclassified, showing no immunohistochemical staining with any of the 10 hormonal peptides tested. Outcome was clearly correlated with tumour group. Among the 14 patients who died of the disease, four had group IV and 10 group III tumours. Thus, unclassified asymptomatic tumours without immunohistochemical staining had a poorer prognosis than asymptomatic tumours with staining.

CONCLUSION

This study validates the Capella classification as easy to apply and useful in predicting clinical outcome.

[Computer-based hospital transfusion process: why and how does one establish a link between continuous quality improvement and clinical information system?]

Within a hospital, the need for a computer-based transfusion system has became mandatory. It facilitates the tracing of healthcare activities, which is the basis of the security of the care and a functional element of continuous quality improvement procedures. In order to implement this traceability, reactive and real-time information systems are needed close to healthcare participants, which is not the case of current information systems which rely on a recorded collection of data, far from the needs of the caregiver, and mainly answering to an objective evaluation of results. In the context of continuous quality improvement programmes started in our hospital, hemovigilance was the first to use a process analysis approach, from the prescription of blood units to their administration and follow-up. Several questions arise from this: 1) how to use the process analysis work to specify the users' needs of a generalized and real-time transfusion information system? 2) how to spread this model to other healthcare activities? 3) how to integrate or interface the whole of these quality programmes with a clinical information system? A user-centered methodology was used, based on 'usage cases'. For each step of the transfusion process, this method allowed us to specify participants, data necessary for an activity (observed, deduced or decision-support data), data issuing from the activity, roles (the interaction between user and activity) and functions (the result of the interaction between user and activity).

[Epidemiologic surveillance of dengue fever: non specific alert system in the hospital milieu in Cayenne]

A retrospective study was carried out in the General Hospital of Cayenne, the main city in French Guiana, where malaria is endemic and dengue fever constitutes a permanent threat. The aim of this study was to test an alert system for epidemic outbreaks of dengue fever. Patients attending the emergency ward and for whom a search of Plasmodium was prescribed were included. In 90% of cases, patients were febrile, presenting clinical symptoms compatible with malaria or dengue fever-like syndrome. The period of survey covered 39 months (January 1996 to March 1999). Three indices were studied; two non specific: EMN (Emergency Malaria Negative--UPN in French): number of negative malaria blood tests for patients having consulted the emergency ward; EMNT (Emergency Malaria Negative Thrombopenia--UPNT in French): UPN with platelets < 150.000; and one more specific; number of hospitalised dengue fever cases according to data from a hospital programme on medical systems information. EMN weekly follow-ups led to three epidemic alerts, two of which turned out to be crucial for dengue. Accounting for thrombopenia (EMNT) reinforced the specificity. This simple and reactive alert system should incite increased serological and virological surveillance and contribute to precocious antivectorial control measures in districts where several dengue fever cases are suspected.

A semantic-based kernel for advanced health information systems

This paper reports on the design and development of an infrastructure allowing one to share and exchange multimedia data in the context of a health network. A single technology exploiting a semantic model of the hospital universe provides users with information and data of diverse origins, generated by the various actors or departments of the health organization. Functions provided include act management and patient record management governed by domain semantics. The functionality has been validated through laboratory experiments against the requirements of protocol directed care and health networks. The functionality is integrated into a clinician workstation exploited in the Internet/Intranet environment thanks to a commercial browser. These results have been obtained with the support of several projects in the frame of the Health-Care Telematics Applications Programme of the European Community and of the Eurêka Programme.

Mediation services with health information sources

OBJECTIVES

To design and implement mediators dedicated to access various kinds of information sources in the framework of the project ARIANE.

METHOD

Mediators are dynamically built thanks to three components: pieces of knowledge issued from the UMLS knowledge sources and from a catalog of information sources, processes that translate a query into the syntax of a target source, and communication services provided by operating systems.

RESULTS

A scenario details the complete mediation process with an indexed web site.

CONCLUSION

This approach mixes knowledge and software engineering. It benefits from services provided by operating systems and allows scalability and reusability of software components.

[Neonatal hemochromatosis]

Neonatal hemochromatosis is characterized by abnormal hepatic and extrahepatic iron overload, which spares the reticuloendothelial system. In neonates, hemochromatosis results in an acute and frequently lethal liver failure.

CASE REPORTS

We report five cases of neonatal hemochromatosis which demonstrate various aspects of this disorder and underline the complexity of both the diagnosis and treatment. Case 3 had an extremely low arterial pressure, a presentation not yet described.

CONCLUSION

Neonatal hemochromatosis should be suspected in the presence of cholestasis with liver failure of perinatal onset and with high blood level ferritin. Abdominal nuclear magnetic resonance and/or liver biopsy can confirm neonatal hemochromatosis. For one of our patients, a medical treatment allowed us to perform a liver transplantation.

Integration of health care process analysis in the design of a clinical information system: applying to the blood transfusion process

Hospital information systems have to support quality improvement objectives. The requirements of the system have to meet users' needs in relation to both the quality (efficacy, conformity, safety) and the monitoring of all health care activities (traceability). Information analysts need complementary methods to conceptualize clinical information systems that provide actors with immediate individual benefits and guide collective behavioral changes. A methodology is proposed to elicit users' needs using a process-oriented analysis, and it is applied to the field of blood transfusion. We defined a process data model, the main components of which are: activities, resources, constrains, guidelines and indicators. Although some aspects of activity, such as "where", "what else", and "why" are poorly represented by the data model alone, this method of requirement elicitation fits the dynamic of data input for the process to be traced. A hierarchical representation of hospital activities has to be found for this approach to be generalised within the organisation, for the processes to be interrelated, and for their characteristics to be assessed.

Confidentiality issues within a clinical information system: moving from data-driven to event-driven design

Within a hospital, the moving of medical information systems from retrospective data-gathering methods to prospective clinical information systems raises the question of the confidentiality of patient data. A method of improving the traditional matrix model usually used to achieve access controls is described. The event-driven model refers to the way a security system ensures that a given user has a valid "need-to" relationship to a given patient. Events are defined as the occurrence of specific data that trigger the creation or the updating of the relationship between the identity of a user and the identity of a patient (e.g., admission, discharge, transfer, prescription, and report). The creation and the deletion of the relationships between users and patients are based on numerous repositories and working lists of patients. This implementation requires an organization of the hospital activities which is able to manage, in a real-time manner, those repositories as closely as possible to the steps occurring during the patient's care process. Although this approach seems to reasonably fit the dynamic of the care process, it adds significant organizational constraints.

Genetic alterations in early-onset invasive breast carcinomas: correlation of c-erbB-2 amplification detected by fluorescence in situ hybridization with p53 accumulation and tumor phenotype

p53 tumor-suppressor gene mutation and p53 protein over-expression have been reported with higher frequency in early-onset breast carcinomas (EOBC). Given the role attributed to normal p53 protein in DNA-repair mechanisms, other somatic genomic alterations would be expected to be associated with this abnormality. Amplification of the c-erbB-2 (HER-2/neu) oncogene and over-expression of the corresponding p185erbB-2 protein have been linked to prognosis and response to therapy in breast cancer. In a retrospective study of 62 formalin-fixed paraffin-embedded invasive EOBC (diagnosed at 35 years or less), the amplification status of the c-erbB-2 gene detected by fluorescence in situ hybridization (FISH) using a unique sequence probe was compared with p53 protein accumulation measured by immunohistochemistry (IHC) and phenotypic features. p185erbB2-protein expression was also detected by immunohistochemistry, together with estrogen-receptor (ER) and progesterone-receptor (PR) expression. The data for a sub-set of 33 node-negative EOBC cases were compared with 70 node-negative tumors diagnosed in women above 36 years of age. Compared with node-negative BC in older women, node-negative EOBC was significantly more likely to feature high grade, high proliferation rate, negative ER and/or PR and p53 over-expression (p < 0.05). A trend toward a higher incidence of c-erbB-2 amplification in EOBC (21% vs. 9%) reached near-significance (p = 0.07). In EOBC, c-erbB-2 amplification and p53 over-expression were not associated with high tumor grade or high cell-proliferation rate, in contrast to the significant associations of these markers in tumors in older women. Abnormalities in tumor markers, including c-erbB-2 gene amplification and p53-protein over-expression, occur at different rates in women with EOBC as compared with BC developing in older women. This finding may reflect a different pathogenesis for EOBC, and warrants further investigation.

Mother-to-child transmission of human T-cell-leukemia/lymphoma virus type I: implication of high antiviral antibody titer and high proviral load in carrier mothers

In order to gain new insights into the risk factors influencing human-T-cell-leukemia/lymphoma-virus-type-I (HTLV-I) mother-to-child transmission, a retrospective study of HTLV-I infection among children born to HTLV-I-seropositive women was carried out in a highly HTLV-I-endemic population of African origin living in French Guyana. The study covered 81 HTLV-I-seropositive mothers and their 216 children aged between 18 months old and 12 years old. All plasma samples were tested for the presence of HTLV-I antibodies by ELISA, immunofluorescence assay and Western blot. HTLV-I provirus was detected, in the DNA extracted from peripheral-blood mononuclear cells, by polymerase chain reaction (PCR) using primers specific for 3 different HTLV-I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. Out of the 216 children, 21 were found to be HTLV-I-seropositive, giving a crude HTLV-I transmission rate of 9.7%, while among the 180 breast-fed children 10.6% were HTLV-I-seropositive. Perfect concordance between serological and PCR results was observed, and none of the 195 HTLV-I-negative children was found HTLV-I-positive by PCR. In conditional (by family) logistic-regression models, HTLV-I seropositivity in children was associated with an elevated maternal anti-HTLV-I-antibody titer (OR 2.2, p = 0.0013), a high maternal HTLV-I proviral load (OR 2.6, p = 0.033) and child's gender, girls being more frequently HTLV-I-infected than boys: OR 3.6, p = 0.0077 in the model including maternal anti-HTLV-I-antibody titer and OR 4.1, p = 0.002 in the model including the maternal HTLV-I proviral load.

Mother-to-child transmission of human T-cell-leukemia/lymphoma virus type I: implication of high antiviral antibody titer and high proviral load in carrier mothers

In order to gain new insights into the risk factors influencing human-T-cell-leukemia/lymphoma-virus-type-I (HTLV-I) mother-to-child transmission, a retrospective study of HTLV-I infection among children born to HTLV-I-seropositive women was carried out in a highly HTLV-I-endemic population of African origin living in French Guyana. The study covered 81 HTLV-I-seropositive mothers and their 216 children aged between 18 months old and 12 years old. All plasma samples were tested for the presence of HTLV-I antibodies by ELISA, immunofluorescence assay and Western blot. HTLV-I provirus was detected, in the DNA extracted from peripheral-blood mononuclear cells, by polymerase chain reaction (PCR) using primers specific for 3 different HTLV-I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. Out of the 216 children, 21 were found to be HTLV-I-seropositive, giving a crude HTLV-I transmission rate of 9.7%, while among the 180 breast-fed children 10.6% were HTLV-I-seropositive. Perfect concordance between serological and PCR results was observed, and none of the 195 HTLV-I-negative children was found HTLV-I-positive by PCR. In conditional (by family) logistic-regression models, HTLV-I seropositivity in children was associated with an elevated maternal anti-HTLV-I-antibody titer (OR 2.2, p = 0.0013), a high maternal HTLV-I proviral load (OR 2.6, p = 0.033) and child's gender, girls being more frequently HTLV-I-infected than boys: OR 3.6, p = 0.0077 in the model including maternal anti-HTLV-I-antibody titer and OR 4.1, p = 0.002 in the model including the maternal HTLV-I proviral load.

Mother-to-child transmission of human T-cell-leukemia/lymphoma virus type I: implication of high antiviral antibody titer and high proviral load in carrier mothers

In order to gain new insights into the risk factors influencing human-T-cell-leukemia/lymphoma-virus-type-I (HTLV-I) mother-to-child transmission, a retrospective study of HTLV-I infection among children born to HTLV-I-seropositive women was carried out in a highly HTLV-I-endemic population of African origin living in French Guyana. The study covered 81 HTLV-I-seropositive mothers and their 216 children aged between 18 months old and 12 years old. All plasma samples were tested for the presence of HTLV-I antibodies by ELISA, immunofluorescence assay and Western blot. HTLV-I provirus was detected, in the DNA extracted from peripheral-blood mononuclear cells, by polymerase chain reaction (PCR) using primers specific for 3 different HTLV-I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. Out of the 216 children, 21 were found to be HTLV-I-seropositive, giving a crude HTLV-I transmission rate of 9.7%, while among the 180 breast-fed children 10.6% were HTLV-I-seropositive. Perfect concordance between serological and PCR results was observed, and none of the 195 HTLV-I-negative children was found HTLV-I-positive by PCR. In conditional (by family) logistic-regression models, HTLV-I seropositivity in children was associated with an elevated maternal anti-HTLV-I-antibody titer (OR 2.2, p = 0.0013), a high maternal HTLV-I proviral load (OR 2.6, p = 0.033) and child's gender, girls being more frequently HTLV-I-infected than boys: OR 3.6, p = 0.0077 in the model including maternal anti-HTLV-I-antibody titer and OR 4.1, p = 0.002 in the model including the maternal HTLV-I proviral load.

History of Joubert syndrome and a 30-year follow-up of the original proband

The 1960s were a period of great flowering in the recognition of neurologic disorders in children. The so-called ataxic cerebral palsies were an especially fertile field waiting for clarification. Congenital ataxia coupled with hyperpnea-apnea, abnormal eye movements, and retardation was identified as an autosomal-recessive syndrome eponimically associated with the senior author, Marie Joubert. The disorder, though rare, is increasingly recognized and a lay society dedicated to family support and research has been formed. In preparation for a recent symposium the original proband was re-examined 30 years later and the manifestations in adults clarified. Severe dysarthria was the most striking feature in this man, the hyperpnea-apnea had diminished, and the abnormal eye movements were less striking. Ataxia was still present but not severe. Poor judgment and borderline intelligence rounded out the clinical picture. Modern imaging has clarified, in part, the anatomic basis of this syndrome.

Implementation of a database on drugs into a university hospital Intranet

Several databases on drugs have been developed worldwide for drug information functions whose sources are now electronically available. Our objective was to implement one of them in our University hospitals information system. Thériaque is a database which contains information on all the drugs available in France. Before its implementation we modeled its content (chemical classes, active components, excipients, indications, contra-indications, side effects, and so on) following an object-oriented method. From this model we designed dynamic HTML pages according to the Microsoft's Internet Database Connector (IDC) technics. This allowed a fast implementation and does not imply to port a client application on the thousands of workstations over the network of the University hospitals. This interface provides end-users with an easy-to-use and natural way to access information related to drugs in an Intranet environment.

Conceptual integration of information databases into an Intranet

Large information systems handle massive volume of data stored in heterogeneous sources of information. Each server has its own model of concepts representation with regard to its aims. One of the main problems encountered by end-users when accessing different servers is to match their own viewpoint on biomedical concepts with their various representations that are made in the database servers. The aim of the project ARIANE is to provide end-users with easy-to-use and natural means to access and query heterogeneous information databases. The objectives of this research work consist in building a conceptual interface by means of the Internet technology inside an enterprise Intranet, and to propose a method to realize it. Moreover, this method provides designers of web sites with a powerful tool to manage them on the basis of an ontology of the biomedical domain. This method is based on the knowledge sources provided by the Unified Medical Language System project of the U.S. National Library of Medicine and exploits intensively the conceptual graphs theory.

Predictive factors for node involvement in papillary thyroid carcinoma. Univariate and multivariate analyses

For patients with papillary thyroid carcinoma, lymph node involvement is a common complication, resulting in node dissection and its resulting morbidity. To determine means of limiting lymph node dissections, we attempted to define intra-operative criteria predictive of node metastasis and so identify the patients likely to benefit from this procedure. This retrospective study concerned 158 patients (118 female) treated between 1974 and 1996 for papillary thyroid carcinoma by total thyroidectomy associated with bilateral (central and lateral) (n = 119) or unilateral (n = 39) dissection. The following criteria were used to study the predictive value of node involvement: age, sex, tumour size, tumour site, uni- or multifocality, existence or not of a tumour capsule, existence or not of perithyroid involvement and presence or not of vascular invasion. 99 patients (63%) had node involvement. Four factors showed predictive value for node involvement in univariate analysis: vascular invasion (P = 0.02), male sex (P = 0.008), absence of a tumour capsule (P < 0.0001) and perithyroid involvement (P < 0.0001). Two factors were predictive in multivariate analysis: absence of a tumour capsule and perithyroid involvement. Our results enabled us to calculate the risk of node involvement for each patient as a function of the existence of a peritumoral capsule and/or perithyroid involvement and to determine the indication for dissection. When neither of these factors was present, the risk of node involvement was 38.3% and dissection was not considered essential. If both risk factors were found, the risk was 87.1% and dissection was considered necessary.

Quality criteria and access characteristics of Web sites: proposal for the design of a health Internet directory

The increasing volume of information available on the Internet today is a problem for health care professionals who want to access rapidly data of high quality. Usual search engines and directories are not sufficient to satisfy their needs. Moreover, the information published by Web sites is not always guaranteed. Some institutions around the word deal with the definition of a set of criteria for the evaluation of medical Web sites. We base our current work on the technologies we developed previously in order to integrate sources of information of various kinds using the "Unified Medical Language System" knowledge bases. This paper focuses on quality criteria and access characteristics Web sites should satisfy to be registered in a "Health Internet Directory". The design of such a system is proposed and discussed.