Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method

The scope of this work was the determination of kinetic parameters of the thermal oxidative degradation of a Mediterranean scrub using a hybrid method developed at the laboratory. DSC and TGA were used in this study under air sweeping to record oxidative reactions. Two dominating and overlapped exothermic peaks were recorded in DSC and individualized using an experimental and numerical separation. This first stage allowed obtaining the enthalpy variation of each exothermic phenomenon. In a second time, a model free method was applied on each isolated curve to determine the apparent activation energies. A reactional kinetic scheme was proposed for the global exotherm composed of two independent and consecutive reactions. In fine mean values of enthalpy variation and apparent activation energy previously determined were injected in a model fitting method to obtain the reaction order and the preexponential factor of each oxidative reaction. We plan to use these data in a sub-model to be integrated in a wildland fire spread model

Caractérisation de l’apoptose observée dans le système limbique après une ischémie myocardique transitoire chez le rat

Au niveau clinique, il a été observé que de 15 à 30 % des patients qui ont subi un infarctus du myocarde développent une dépression majeure. De plus, la population atteinte de dépression post-infarctus présente un risque de mortalité de trois à quatre fois plus élevé, et ce, en comparaison avec la population non dépressive post-infarctus. Dans un modèle de rat développé pour étudier la dépression post-infarctus, des cellules apoptotiques ont été retrouvées au niveau du système limbique. Il apparaît que les cytokines seraient en partie responsables de cette mort cellulaire qui relie le cœur en ischémie et le système nerveux central. Donc, les objectifs de cette thèse sont : 1) de caractériser spatialement et temporellement la survenue de la mort cellulaire par apoptose dans les structures du système limbique du rat, à la suite d’un infarctus du myocarde ; 2) de déterminer l’effet de l’anti-inflammatoire celecoxib sur cette apoptose observée au niveau de l’amygdale et de déterminer l’implication de l’enzyme COX-2 ; 3) de déterminer l’implication de la cytokine pro-inflammatoire TNF-α dans l’apoptose observée au niveau des structures du système limbique du rat, à la suite d’un infarctus du myocarde. Afin d’atteindre ces objectifs, les rats ont subi une ischémie de 40 minutes, suivi d’une période de reperfusion qui varie d’un protocole à l’autre (15 minutes, 24, 48, 72 heures ou 7 jours). De plus, en fonction du protocole, ces rats ont été traités avec soit du célécoxib (inhibiteur sélectif de la COX-2), soit avec du PEG sTNF-R1 (inhibiteur du TNF-α). À la suite de ces protocoles, les rats ont été sacrifiés, la taille de l’infarctus a été déterminée et les différentes structures cérébrales du système limbique prélevées. Des tests biochimiques propres à chaque protocole ont été réalisés afin de documenter l'apoptose. Il a alors été observé qu’aucun des deux traitements ne présentait d’effet sur la taille de l’infarctus. L’étude de l’apoptose dans le système limbique a révélé que : 1) le processus apoptotique se mettait en place dans l’hippocampe dès les 15 premières minutes de reperfusion suivant l’infarctus du myocarde et que ce processus était spatialement dynamique dans le système limbique jusqu’au septième jour postreperfusion ; 2) il est apparu que la COX-2 était impliquée dans l'apoptose du système limbique ; 3) il a été observé que le TNF-α périphérique était impliqué dans ce processus apoptotique après 72 heures de reperfusion en activant la voie extrinsèque de l'apoptose. Ces résultats ont permis de caractériser la survenue de l’apoptose au niveau du système limbique chez le rat à la suite d’un infarctus du myocarde et de documenter l'implication de la COX-2 et du TNF-α dans ce processus. Bien que ces résultats n’apportent pas de schémas thérapeutiques clairs ou de mécanismes physiopathologiques globaux ces derniers permettent une meilleure compréhension de la relation existante entre le cœur et le système nerveux central dans le cadre de l’infarctus du myocarde. De manière moins spécifique ils précisent la relation entre le système inflammatoire et le système nerveux central.About 15 to 30% of clinical patients with myocardial infarction develop major depression. This population is three to four times more vulnerable to fatalities such as death when compared to the non depressed post-myocardial population. In a rat model, developed in order to study post myocardial infarct depression, apoptotic cells within the limbic system have been found. It has been shown that cytokines could be responsible for the cell death linking the ischemic heart to the central nervous system. Thus, the aims of this thesis are: 1) to characterize the spatial time course of the apoptotic cell death within the limbic system, following a myocardial infarct, in a rat model; 2) to determine the effect of the anti-inflammatory celecoxib on this apoptosis in the amygdala and determine the COX-2 enzyme’s implication; 3) to determine the implication of the pro-inflammatory cytokine TNF-α in the apoptosis observed within the limbic system, following a myocardial infarct, in a rat model. In order to achieve these goals, rats were submitted to 40 minutes of myocardial ischemia followed by a variable reperfusion period (15 minutes, 24, 48, 72 hours or 7 days). Moreover, depending on the protocol, rats were treated with celecoxib (COX-2 selective inhibitor), or with PEG sTNF-R1 (TNF-α inhibitor). At the end of each respective reperfusion period, rats were sacrificed, infarct size was determined and the different structures of the limbic system were dissected for further analysis. Biochemical tests, specific to each protocol were performed in order to characterize this apoptosis. With respect to obtained results, we observed that the infarct size was impacted by none of the two treatments. Apoptosis study within the limbic system revealed that: 1) the apoptotic process was activated in the hippocampus area within the first 15 minutes of reperfusion and this process was spatially dynamic in the limbic system until the seventh day of reperfusion; 2) it appeared that COX-2 was implicated in the apoptosis in the limbic system; 3) peripheral TNF-α was implicated in the apoptotic process after 72 hours of reperfusion by activating the extrinsic and intrinsic pathways of apoptosis. These results allowed characterization of apoptosis within the limbic system, in a rat model, following a myocardial infarct and the establishment of the implication of COX-2 and TNF-α in this process. Although these results do not provide any clear therapeutic schemas or global physiopathological mechanisms, they allow a better comprehension of the existing relationship between the heart and the central nervous system within the myocardial infarct context. To a less specific extent these results bring more information on the relationship between the inflammatory system and the central nervous system

Determinants In HIV Counselling And Testing In Couples In North Rift Kenya

Background: Voluntary HIV counselling and testing (VCT) has been shown to be an acceptable and effective tool in the fight against HIV/AIDS. Couple HIV Counselling and Testing (CHCT) however, is a relatively new concept whose acceptance and efficacy is yet to be determined.Objective: To describe factors that motivate couples to attend VCT as a couple. Design: A cross sectional qualitative study.Setting: Moi Teaching and Referral Hospital and Moi University, School of Medicine, Eldoret, KenyaSubjects: Seventy one individuals were interviewed during KII (9) and dyad interviews (31 couples). Ten FGDs involving a total of 109 individuals were held. Results: Cultural practices, lack of CHCT awareness, stigma and fear of results deter CHCT utilisation. Location of centre where it is unlikely to be associated with HIV testing, qualified professional staff and minimal waiting times would enhance CHCT utilisation.Conclusions: CHCT as a tool in the fight against HIV/AIDS in this region of Kenya is feasible as the factors that would deter couples are not insurmountable

Stakeholders perception of HIV sero-discordant couples in western Kenya

Objective: To describe the perceptions of key stakeholders regarding the counselling needs of HI V sero-discordant couples as part of preparation for a clinical trial involving HIV sero-discordant couples. Design: Qualitative study using key informant and couple interviews. Setting: Moi Teaching and Referral Hospital (MTRH). Subjects: A purposive sample of nine key informants and 31 couple interviews totaling 71 participants. The couple interviews consisted of HI V untested, HI V concordant (positive and negative) and discordant couples. Results: Seventy one individuals participated in nine key informant and 31 couple interviews. The responses identified the following as key issues in counselling HIV discordant couples: The need for education on the meaning of HI V sero-discordancy including potential sources of infection; assistance in disclosing HIV test results to one\'s partner; discussion of the stigma surrounding formula feeding. Overall, the participants supported safer sexual practices in discordant partnerships. Conclusions: Psychosocial support of HI V sero-discordant couples should include messages about the meaning, mechanisms and implications of sero-discordancy. Culturally appropriate HI Vdisclosure and safer sex messages are also needed to support these partnerships. East African Medical Journal Vol. 85 (7) 2008: pp. 326-33

Symptom screen: diagnostic usefulness in detecting pulmonary tuberculosis in HIV-infected pregnant women in Kenya

OBJECTIVE: To determine the diagnostic usefulness of tuberculosis (TB) symptom screening to detect active pulmonary TB among human immunodeficiency virus (HIV) infected pregnant women in two PMTCT (prevention of mother-to-child transmission) clinics in western Kenya that are supported by the United States Agency for International Development–Academic Model Providing Access to Healthcare partnership. DESIGN: Cross-sectional study. Participants were interviewed for TB symptoms with a standardized questionnaire (cough >2 weeks, fever, night sweats, weight loss or failure to gain weight). Those with cough submitted sputum specimens for smear microscopy for acid-fast bacilli and mycobacterial culture. Women at >14 weeks gestation underwent shielded chest radiography (CXR). RESULTS: Of 187 HIV-infected women, 38 (20%) were symptom screen-positive. Of these, 21 had a cough for >2 weeks, but all had negative sputum smears and mycobacterial cultures. CXRs were performed in 26 symptomatic women: three were suggestive of TB (1 miliary, 1 infiltrates and 1 cavitary). Of 149 women with a negative symptom screen, 100 had a CXR and seven had a CXR suggestive of TB (1 cavitary, 2 miliary and 4 infiltrates). CONCLUSION: This study did not support the utility of isolated symptom screening in identification of TB disease in our PMTCT setting. CXR was useful in identification of TB suspects in both symptomatic and asymptomatic women

Has the phasing out of stavudine in accordance with changes in WHO guidelines led to a decrease in single-drug substitutions in first-line antiretroviral therapy for HIV in sub-Saharan Africa?

This version is the Accepted Manuscript and is published in final edited form as: AIDS. 2017 January 02; 31(1): 147–157. doi:10.1097/QAD.0000000000001307OBJECTIVE: We assessed the relationship between phasing out stavudine in first-line antiretroviral therapy (ART) in accordance with WHO 2010 policy and single-drug substitutions (SDS) (substituting the nucleoside reverse transcriptase inhibitor in first-line ART) in sub-Saharan Africa. DESIGN: Prospective cohort analysis (International epidemiological Databases to Evaluate AIDS-Multiregional) including ART-naive, HIV-infected patients aged at least 16 years, initiating ART between January 2005 and December 2012. Before April 2010 (July 2007 in Zambia) national guidelines called for patients to initiate stavudine-based or zidovudine-based regimen, whereas thereafter tenofovir or zidovudine replaced stavudine in first-line ART. METHODS: We evaluated the frequency of stavudine use and SDS by calendar year 2004-2014. Competing risk regression was used to assess the association between nucleoside reverse transcriptase inhibitor use and SDS in the first 24 months on ART. RESULTS: In all, 33 441 (8.9%; 95% confience interval 8.7-8.9%) SDS occurred among 377 656 patients in the first 24 months on ART, close to 40% of which were amongst patients on stavudine. The decrease in SDS corresponded with the phasing out of stavudine. Competing risks regression models showed that patients on tenofovir were 20-95% less likely to require a SDS than patients on stavudine, whereas patients on zidovudine had a 75-85% decrease in the hazards of SDS when compared to stavudine. CONCLUSION: The decline in SDS in the first 24 months on treatment appears to be associated with phasing out stavudine for zidovudine or tenofovir in first-line ART in our study. Further efforts to decrease the cost of tenofovir and zidovudine for use in this setting is warranted to substitute all patients still receiving stavudine

Admission Characteristics, Diagnoses And Outcomes Of HIV-Infected Patients Registered In An Ambulatory HIV-Care Programme In Western Kenya

Objective: To determine admissions diagnosis and outcomes of HIV-infected patients attending AMPATH ambulatory HIV-care clinics. Design: Prospective cohort study. Setting: Academic Model for Prevention and Treatment of HIV/ AIDS (AMPATH) ambulatory HIV-care clinic in western Kenya. Results: Between January 2005 and December 2006, 495 HIV-infected patients enrolled in AMPATH were admitted. Median age at admission was 38 years (range: 19 - 74), 62% females, 375 (76%) initiated cART a median 56 days (range: 1- 1288) before admission. Majority (53%) had pre-admission CD4 counts 200 cells/ml. Common admissions diagnoses were: tuberculosis (27%); pneumonia (15%); meningitis (11%); diarrhoea (11%); malaria (6%); severe anaemia (4%); and toxoplasmosis (3%). Deaths occurred in 147 (30%) patients who enrolled at AMPATH a median 44 days (range: 1 - 711) before admission and died a median 41 days (range: 1 -713) after initiating cART. Tuberculosis (27%) and meningitis (14%) were the most common diagnoses in the deceased. Median admission duration was six days (range: 1 - 30) for deceased patients and eight days (range: I - 44) for survivors (P=0.0024). Deceased patients enrolled in AMPATH or initiated cART more recently, had lower CD4 counts and were more frequently lost to follow-up than survivors (