Université de Sherbrooke

About: Université de Sherbrooke is a education organization based out in Sherbrooke, Quebec, Canada. It is known for research contribution in the topics: Population & Receptor. The organization has 14922 authors who have published 28783 publications receiving 792511 citations. The organization is also known as: Universite de Sherbrooke & Sherbrooke University.

Signal transduction and functional changes in neutrophils with aging

Abstract: It is well known that the immune response decreases during aging, leading to a higher susceptibility to infections, cancers and autoimmune disorders Most widely studied have been alterations in the adaptive immune response Recently, the role of the innate immune response as a first-line defence against bacterial invasion and as a modulator of the adaptive immune response has become more widely recognized One of the most important cell components of the innate response is neutrophils and it is therefore important to elucidate their function during aging With aging there is an alteration of the receptor-driven functions of human neutrophils, such as superoxide anion production, chemotaxis and apoptosis One of the alterations underlying these functional changes is a decrease in signalling elicited by specific receptors Alterations were also found in the neutrophil membrane lipid rafts These alterations in neutrophil functions and signal transduction that occur during aging might contribute to the significant increase in infections in old age

Age- and education-specific reference values for the Mini-Mental and modified Mini-Mental State Examinations derived from a non-demented elderly population.

Abstract: Main objective. To report age- and education-specific reference values for the Mini-Mental State Examination (MMSE) and Modified Mini-Mental State (3MS) Examination. Design. Cross-sectional study. Setting. Community and institutional settings in five regions across Canada. Participants. 7754 subjects aged 65 and over randomly chosen to take part in the Canadian Study of Health and Aging. Subjects classified as cognitively impaired or demented following a clinical and neuropsychological examination were excluded. Measurements. Total scores on the MMSE and 3MS, and the degree to which they are influenced by the age, sex, education, mother tongue and living environment of the subject. Results. Reference values on the two tests are reported through various descriptive statistics for five age groups and four education levels. These values decrease with age and increase with years of schooling. Test scores are also influenced by the subject's sex and mother tongue, albeit to a lesser extent. These observations led to the development of predictive equations of the performance to be expected from a ‘normal’ elderly subject, given his/her sociodemographic characteristics. Conclusion. The use of the reference values and related predictive equations will allow the clinician to interpret a patient's performance on two widely used cognitive tests, in light of the value expected from a group of ‘normal’ subjects with the same sociodemographic profile. © 1997 John Wiley & Sons, Ltd.

Radiation hardness of gallium nitride

Abstract: Gallium nitride (GaN) light emitting diodes (LEDs) were irradiated at room temperature with electrons in the range 300-1400 keV A threshold energy of 440 keV was observed, corresponding to a gallium atom displacement energy of 19/spl plusmn/2 eV This value of the displacement energy compares with that of silicon carbide but is smaller than that of diamond and larger than that of gallium arsenide (GaAs) No threshold energy for the nitrogen atom was observed It is concluded that the nitrogen sublattice repairs itself through annealing The measured displacement energy is used to determine the Rutherford cross section, which permits a theoretical comparison of electron and proton irradiation damage in GaN The effects of 25 MeV electrons on gallium nitride films have been studied by photoluminescence (PL), and according to the literature, they introduce transitions in the near infrared part of the spectrum Experiments on gallium nitride films using 2 MeV protons are reported in this work The same transitions in the near infrared part of the spectrum are observed by PL It is deduced that 2 MeV protons are about 1000 times more damaging than 25 MeV electrons The Rutherford cross section predicts a value of 214 The difference is attributed to the defect recombination rate which depends on the particle type The nature of the transitions in the near infrared part of the spectrum is reviewed The GaN films were annealed at 400/spl deg/C for 30 min As a result of annealing, another transition appears in the green part of the spectrum Transitions involving the gallium vacancy in irradiated GaN are discussed