Medical control of bioterrorism

Against the recently accrued risk of bioterrorism, the Biotox plan has been set up in order to take in charge any person that could be facing a potential terrorist contamination. It has to take into consideration the components of bioterrorism, i.e. the incubation period, the function of bacterial or viral agents, the variable number of concerned people, the difficulty of alert launching, and the diagnosis of the responsible agent. This plan relies on hospitals comprising departments of infectious diseases. Those are specifically in charge of informing, organising, and coordinating the reception of people having been in contact or infected by infectious agents, in order to isolate and treat them properly. The recent experience has allowed to test this plan, to precise and correct some of its features.     

An agent-based model of sleeping sickness: simulation trials of a forest focus in southern Cameroon

An agent-based model (AMB) used to simulate the spread of Human African Trypanosomiasis is presented together with the results of simulations of a focus of the disease. This model is a completely spatialized approach taking into account a series of often overlooked parameters such as human behaviour (activity-related movements), the density and mobility of the disease vectors--tsetse flies (Glossina spp.)--and the influence of other tsetse feeding hosts (livestock and wild animal populations). The agents that represent humans and tsetse flies move in a spatially structured environment managed by specialized location agents. Existing compartmental mathematical models governed by differential equations fail to incorporate the spatial dimension of the disease transmission. Furthermore, on a small scale, transmission is unrealistically represented by entities less than one. This ABM was tested with data from one village of the Bipindi sleeping sickness focus (southern Cameroon) and with obtained realistic simulations of stable transmission involving an animal reservoir. In varying different spatial configurations, we observe that the stability of spread is linked to the spatial complexity (number of heterogeneous locations). The prevalence is very sensitive to the human densities and to the number of tsetse flies initially infected in a given location. A relatively low and durable prevalence is obtained with shortening the phase I. In addition, we discuss some upgrading possibilities, in particular the linkage to a Geographical Information System (GIS). The agent-based approach offers new ways to understanding the spread of the disease and a tool to evaluate risk and test control strategies.     

Epidemiological studies on aging in France: from the PAQUID study to the Three-City study

Follow-up of cohorts recruited in general population with active screening and diagnosis of incident cases, is the most appropriate epidemiological design for studying incidence and risk factors of Alzheimer disease and other types of dementia. In France, people considered in the PAQUID study, then in the EVA study, have been the first cohorts on dementia. They have prepared the way for the Three-City (3C) study, conducted in Bordeaux, Dijon and Montpellier. About 9500 persons aged 65 years and over have been recruited in these three cities and will be followed-up during four years. The main objective of the 3C study is to investigate the relation between vascular risk and neurodegenerative diseases. The 3C study will provide essential data for defining strategies for dementia prevention. To measure the impact of the strategies on the incidence of dementia and the social burden of this disease will be an important public health objective in the near future.     

Multiplicative genetic effects in scrapie disease susceptibility

Despite experimental evidence that scrapie is an infectious disease of sheep, variations of the occurrence of the natural disease suggest an influence of host genetic factors. It has been established that the genetic polymorphism of the prion protein (PrP) gene is correlated to the incidence of scrapie and to the survival time: five polymorphisms have been described by variations at amino-acid codons 136, 154 and 171. In this paper we study the effect on scrapie susceptibility of the pairing of the five allelic variants known to exist: we show that scrapie susceptibility is given by the produce of the elementary allelic factors. This first well-documented evidence of a multiplicative property of genetic risk factors could give hints on the underlying mechanisms of prion-induced neurodegenerative diseases.     

Research strategies in the pharmaceutical industry to cope with the problems of ageing

The present research strategies for ageing are focussed around three areas. The first area is the demographic study of the present-day populations and those in the future. The analysis of the evolution of the metropolitan French population from 1950 to 2050 indicates that the proportion of subjects aged greater than 60 years will pass from 16% to 35%. In addition, the level of dependence of these subjects will vary considerably from one to another. The second area is the integration of epidemiological data of the pathologies related to the aged subject. Numerous epidemiological studies of the aged show that the elderly population is in better health, better informed about the diseases that affect them and also financially more secure, which allows them to take better care of themselves. The epidemiological studies of certain dementias show, for example, that if we reduce the delay to when the disease appears by five years, then we reduce the prevalence by a factor of 2. The third area relates to the important new progress in the understanding of the biological mechanisms involved in cellular ageing. The recent progress in the area of cellular biology has started to decode the complex mechanisms underlying cellular ageing. The important understanding of the phenomena of apoptose with the development of relevant biological models of the natural ageing process have anticipated future treatments and, eventually, the prophylactic treatment of specific pathologies of the elderly patient.     

Grave's disease affecting one thyroid lobe: About 2 cases

Graves’ disease is an autoimmune disorder of thyroid which is characterized by hyperthyroidism, diffuse goiter, ophthalmopathy. Due to the pathophysiological mechanism of the disease, the disease affects both thyroid lobes. Unilateral involvement of the thyroid gland in patients with Graves’ disease is a rare entity, which suggests a difference between the two thyroid lobes. Clarifying this phenomenon could be a line of research for a better understanding of the pathophysiology of Graves's disease. This entity must be known to the clinician in order to take it better and avoid misdiagnosis. Here we present two cases of Graves’ disease which had unilateral involvement of the thyroid gland and discuss the hypotheses explaining this observation.     

Prevention of bioterrorism by vaccines

Prevention against the weapons of bioterrorists is limited by the multiplicity of agents that could be used. Against smallpox, stocks of the classical vaccine must be prepared, but this vaccine is dangerous and we must look for a new and safer vaccine. A vaccine against anthrax is probably possible relatively soon. One may be less optimistic concerning plague, since it is not sure that we could protect against the pulmonary plague, but research in this field is an emergency. The large number of viruses capable of inducing haemorrhagic fevers makes especially difficult the preparation of vaccines against these infections. We must also make available monoclonal antibodies that could be used as therapies against toxin, notably botulism, or against antibiotic-resistant bacteria.     

Influence du type de sol et de ces composantes physicochimiques sur les relations entre une variété de blé (Triticum aestivum L. var. Rescler) et deux souches,agressive et hypoagressive deGaeumannomyces graminis (Sacc.) von Arx et Olivier var.tritici Walker

Résumé 58 échantillons de sol sont collectés dans des parcelles cultivées en blé du Centre et de l'Ouest de la France. Ces sols sont répartis en pots, infestés ou non par une souche agressive ou hypoagressive deGaeumannomyces graminis var.tritici et cultivés en blé pendant 3 mois. Les plantes sont alors arrachées pour appréciation du niveau de maladie et mesure du volume de racines développées dans chaque sol. L'analyse en composantes principales réalisée sur ces variables biologiques et les caractéristiques physicochimiques des sols montre que le niveau de la maladie observé est corrélée négativement avec le niveau potassique et la teneur en sable, corrélé positivement avec la teneur en limon. Dans certains sols il a pu être constaté un développement plus important du système racinaire à la suite de l'infestation par l'un ou l'autre des champignons et l'analyse révèle que ce phénomène est en étroite relation avec la teneur en manganèse échangeable.     

Stem cell therapy: medical advance or moral challenge?Thérapie cellulaire : avance médicale ou défi moral ?

My professional lifetime has seen progress in the biomedical sciences that beggars belief. This has lead to astonishing advances in the ability to prevent and treat disease and, in the developed world at least, people live longer and healthier lives than ever before. Paradoxically, this has gone hand in hand with the growth of a vocal and influential anti-science lobby that not only rejects much modern science but is also deeply suspicious of new medical interventions. The prospect of cell therapy in the near or middle future is their current target especially where the use of embryonic stem cells or of cell nuclear transfer techniques is concerned. The prospect of cell therapy is welcomed with enthusiasm by patients with genetic and degenerative diseases who hope to benefit from them. On the other hand the whole idea is regarded as repugnant by the anti-science lobby. While some of this opposition is essentially luddite in nature, there are some more persuasive arguments raised particularly to any research than uses embryonic or foetal materials. These arguments will be examined critically. The moral problems of denying the sick the hope of effective treatments have to be weighed against those seen in the development of such treatments. (This article is closely based on an already published paper. P. Lachmann, Stem cell research: why is it regarded as a threat? An investigation of the economic and ethical arguments made against research with human embryonic stem cells. EMBO Rep. 2 (3) (2001) 165–168.)     

Arboviruses and epizootic viruses

Some viral diseases are transmitted to human by arthropods (arboviroses), or by animals (zoonoses). Among more than 500 arboviruses and epizootic viruses that are classified into seven families, only a few are responsible for zoonoses or cause severe human diseases. Infected patients may show an acute disease associated with different symptoms, ranging from high fever to encephalitis, pulmonary distress, and haemorrhages. Some diseases show one or more of these symptoms and the factors responsible for severe outcomes, either linked to the virus, or to the host, or to the vector, remain poorly understood. Arboviroses and zoonoses are emerging or re-emerging diseases that need a multidisciplinary effort to control the propagation of the infectious agent and the pathogenesis in infected patients. Some viruses could be used for bioterrorism attacks. In virology, studies on the interactions of the viruses with their vectors and vertebrate hosts and on the pathophysiology of the infections will allow a better prevention of these diseases.