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In common usage and medicine, health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity". A variety of definitions have been used for different purposes over time. Health can be promoted by encouraging healthful activities, such as regular physical exercise and adequate sleep, and by reducing or avoiding unhealthful activities or situations, such as smoking or excessive stress. Some factors affecting health are due to individual choices, such as whether to engage in a high-risk behavior, while others are due to structural causes, such as whether the society is arranged in a way that makes it easier or harder for people to get necessary healthcare services. Still, other factors are beyond both individual and group choices, such as genetic disorders. History The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of

Multidisciplinary Investigation of the Gut-Brain Ecosystem in a Model of Alzheimer's Disease

Arielle Louise Planchette

The search for an understanding of the causal elements that lead to neurodegenerative diseases has motivated researchers for decades. Today, Alzheimer's disease is the most prevalent form of dementia and affects approximately fifty million people worldwide, with only 5% of patients carrying causal genetic mutations. In recent years, studies of animal models as well as observations in humans have brought the gut microbiome to the forefront of AD research, as a significant contributor to the development of Alzheimer's disease. In fact, the gut microbiome is now understood to be a modulator of health and disease in numerous areas of physiology, including energy metabolism, immunity, endocrinology, and most relevant to this thesis, brain health and cognition. The gut microbiome is a complex environment composed of symbiotic bacteria, fungi and viruses (the microbiota) that produce a wide range of signalling molecules that are interpreted both by members of the microbiota and by the host (the microbiome). The host-gut interface is an ecosystem that consists of bi-directional signals and pressures applied by both constituents in order to maintain symbiotic homeostasis. Significant deleterious effects on health occur when homeostasis is lost, which may take place due to a variety of factors. These include host genetic factors and environmental factors, such as diet. Modulation of the gut microbiome has become a potentially viable therapeutic avenue for Alzheimer's disease, though it currently remains at the early stage of discovery. In this thesis, I characterize the evolution of Alzheimer's disease in the 5xFAD mouse model, with a focus on the gut microbiome and on cognitive decline and brain biochemistry. Gut microbiota modulaiton was implemented using germ-free and low-complexity bacterial cocktails, in which I outline the effects microbiota modulation on hallmarks of AD and provide insights into the metabolite profile of the brain altered by the microbiota and AD. The work in this thesis was equally motivated by the development of diagnostic tools using microscopy techniques. Biochemical assessments of disease status and progression provide information pertaining to "what" is interacting and "how much" this affects disease. With microscopy, we may gain the additional knowledge of "where" physiological constituents are and how they interact with the surrounding environment. I describe a novel multi-modal microscopy pipeline that enables the observation of signals of interest in large volumes and at high resolution with a capacity to cross-reference regions of interest in both modalities. The pipeline, known as gutOPT, consists of a sample preparation workflow compatible with mesoscale optical projection tomography (OPT) of fluorescently-labelled targets and subsequent imaging of pre-selected regions of interest in high-resolution modalities, such as confocal microscopy.

EPFL2022

Contribution du SIG à l'analyse des liens déchets-santé en milieu urbain dans les pays en développement

Sonwouignandé Kientga

Among the factors of health risks in urban areas, the solid and liquid wastes worsen particularly the problems of public health in developing countries. Uncontrolled solid waste disposal sites and waste water sites constitute major sources of danger for public health. Often, there is no mapped and documented inventory. The perception of danger related to infectious sources by the exposed populations is generally not well-known and even often ignored by the public institutions in their management policy of health and wastes. The same can be considered for the link between diagnosed diseases in health care services and the presence of waste disposal sites near patients' residences. The goal of this study is to determine the main factors of waste management and their consequences on health. This goal shall be reached using a GIS approach and through a case study concerning two districts in the town of Ouagadougou in Burkina Faso. In detail, the objectives are: i) to build a spatial database for waste disposal sites and public health care management and to propose a methodological approach for the elaboration of a GIS, associating social science, health and the geographical information science; ii) to identify and to analyze indicators of public health related to domestic and industrial waste; ii) to compare these indicators with the different actors' perception, according to the distance and dangers represented by the seriousness of potential danger sources; iv) to analyze if there is a relation between the actors' perception and the diseases diagnosed in health care services; v) to promote GIS in institutional structures in order to facilitate decision-making in waste management. Geographical information science has contributed to the creation of a database containing general geographical data, the disposal waste sites, the data of the actors' perception and health data. This database was used for spatial-thematic, temporal and statistical analyses. At first we have established an inventory of disposal waste sites. Hereafter we have analyzed their spatial influence. We then compared the situation to the perception of dangers and to the people's health risks, related to the distance to sources of potential danger. An analysis of the relation between the disease cases listed (counted) in health centers and the presence of waste (infectious) sources was carried out. This allowed some degree of comparison between the subjectivity of danger perception and the reality. The inventory of potential danger sources and the analysis of their influence spheres shows that 86 % (456 ha) of the study area is threatened by a danger, among which 45 % (235 ha) are considered exposed to a higher danger. The results also show that only 14 % of the population in both sectors (2'574 inhabitants of 18'978 total inhabitants) is not exposed to potential health risks. The analysis of the perceived danger according to the distance revealed that the perceived danger generally decreases proportionally to the distance. Surprisingly certain persons living near a polluted site don't consider the site as dangerous. However others, living far away from the same site, perceive it as dangerous. In these cases the subjective dimension of the perception is thus revealed. The temporal analyses of listed diseases show a correlation between the cases of malaria and the precipitation. The time gap between precipitation-related peaks and malaria cases related peaks varies from two to three months, leaving enough time to take preventive measures. We were not able to establish a link between the patient's residence and pollution sources; because the patient's geographical location is not mentioned in the health care services' registers. A modification of the registration forms has been suggested. The developed methodology and the results gathered led to the establishment of suggestions and recommendations based on the integration of GIS in waste and health management. This study has already contributed to the setup of a geo-information network composed of various actors in waste and health management.

EPFL2008