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Two field hydrogeological surveys were conducted in 1992 and 2013 using hydrochemistry and isotope techniques in the far north region of Cameroon which corresponds to the southern part of Lake Chad basin. The dataset relates to shallow groundwaters of the Quaternary and substratum aquifers that were sampled at the same locations to potentially reveal any temporal variation in the chemical and isotopic characteristics of the groundwater resource. Groundwater shows mainly a CaMg–HCO3 water type but CaMg–Cl–NO3 and NaK–HCO3 water types can also be found. The mineralization is governed essentially by cation exchange processes. However, we also observe dissolution processes of carbonates. Strong anthropogenic contamination of groundwater with nitrates, chlorides, and sulfates is highlighted. It is found that the nitrate content after 20 years has increased by an average factor of 6. These high concentrations in nitrate (up to 600 mg/l) are related to local anthropogenic activities and to the very bad conditions of maintaining of wells and boreholes. The isotopic content is ranging from − 6.46‰ to + 0.46‰ for 18O in 2013 and from − 5.57‰ to + 0.37‰ in 1992 without noticeable evolution. The stable isotope approach underlined the hydraulic connection between basement and quaternary aquifers. Stable isotopes also demonstrated that groundwater in the region is recharged by modern precipitation, but also by evaporated surface waters from rivers during flood episodes. After 20 years, the evolution in Cl−, SO42−, and NO3− concentrations in groundwater is worrying in terms of public health and the government is encouraged to develop a monitoring of this transboundary resource.

Shallow groundwater resources, especially in hard rock environment, constitute an important part of urban water supply in developing countries, appropriate to the low level of economic development. However, increasing urban population and dependence on shallow groundwater systems make it imperative to evaluate the availability and the contamination of these resources, and define new strategies of water exploitation taking into accounts these findings and constrains. This study has been carried out on the shallow groundwater of Yaounde, Central Africa. Based on head slug-in tests, chemical and isotope analyses, we demonstrate the importance of geomorphological settings that constrain hydrogeology, urban occupation and therefore, water exploitation and contamination. Slug test results show spatial variability of well recovery rates with higher values recorded in the valleys compare to the hills, presenting saturated hydraulic conductivity of 10–6–10–8 m/s. Groundwater evolves from recharge zone as Ca–HCO3 in the hillside lateritic system to discharge zone in the slope/valley colluvium/alluvium system as NaK–NO3. The groundwater composition dominated by silicates/water interaction in the hillside lateritic system, and anthropogenic processes in the slopes and valleys. δ15N and δ18O of nitrates indicates that nitrate pollution of groundwater is mainly from sewage and human waste. Shallow groundwater resources in the hillside/new urban districts and to a lesser extent slopes should therefore be protected and prioritised for usability and sustainability. The proposed conceptual scheme for Yaounde can then be used as a guide in the development, exploitation and management of local wells in hard rocks system of Africa.

Douala city, located in the littoral province of Cameroon, receives abundant rainfall quantities due to its geographical position in the Gulf of Guinea and bears considerable surface water and groundwater resources. Due to socioeconomic development and rapid demographic growth in the city and its consequences of unplanned urbanization and improper sanitation system, these water resources are poorly protected and managed. Streams in the Wouri watershed receive large amounts of wastewater discharge, and hundreds of boreholes have been drilled into the aquifer system without any management plan. A detailed hydrodynamic and hydrogeochemistry study in Douala town and its environs was conducted to get a better insight into the groundwater system functioning in order to provide information for the sustainable management and protection of the groundwater resource. Two field campaigns were carried out with 187 samples collected and analyzed for major ions, stable isotopes (18O, 2H), and tritium 3H. The results of the sampling have shown that the weathering of silicate minerals is the dominant geochemical process affecting groundwater chemistry in this system. However, acid rainfall in the humid climate has also caused carbonate mineral dissolution, amorphous silica deposition, and ion exchange reactions to occur in aquifers in the region. The various water types identified were categorized into four major clusters C1 to C4, based on the major ion composition and the local hydrogeological conditions. Environmental isotope data reveal that modern-to-submodern waters occur in the phreatic Quaternary/Mio-Pliocene and Oligocene/Upper Eocene aquifers, respectively. These results corroborate with the conceptual model built where modern groundwater types indicated silicate mineral weathering and calcite dissolution (C1 and C2), whereas submodern groundwater mostly showed silica deposition, ion exchange, and, to a lesser extent, carbonate mineral dissolution (C3 and C4). This improved understanding of the aquifer system functioning is essential to provide a reasonable basis for effective control measures and sustainable water management.

The use of tyrosine kinase inhibitors (TKIs) against EGFR/c-Met in non-small cell lung cancer (NSCLC) has been shown to be effective in increasing patient progression free survival (PFS), but their efficacy is limited due to the development of resistance and tumor recurrence. Therefore, understanding the molecular mechanisms underlying development of drug resistance in NSCLC is necessary for developing novel and effective therapeutic approaches to improve patient outcome. This study aims to understand the mechanism of EGFR/c-Met tyrosine kinase inhibitor (TKI) resistance in NSCLC. H2170 and H358 cell lines were made resistant to SU11274, a c-Met inhibitor, and erlotinib, an EGFR inhibitor, through step-wise increases in TKI exposure. The IC50 concentrations of resistant lines exhibited a 4-5 and 11-22-fold increase for SU11274 and erlotinib, respectively, when compared to parental lines. Furthermore, mTOR and Wnt signaling was studied in both cell lines to determine their roles in mediating TKI resistance. We observed a 2-4-fold upregulation of mTOR signaling proteins and a 2- to 8-fold upregulation of Wnt signaling proteins in H2170 erlotinib and SU11274 resistant cells. H2170 and H358 cells were further treated with the mTOR inhibitor everolimus and the Wnt inhibitor XAV939. H358 resistant cells were inhibited by 95% by a triple combination of everolimus, erlotinib and SU11274 in comparison to 34% by a double combination of these drugs. Parental H2170 cells displayed no sensitivity to XAV939, while resistant cells were significantly inhibited (39%) by XAV939 as a single agent, as well as in combination with SU11274 and erlotinib. Similar results were obtained with H358 resistant cells. This study suggests a novel molecular mechanism of drug resistance in lung cancer.

The objective is to describe the trends of infant feedings choices in HIV context after infant feeding counseling. Descriptive retrospective study: Infant feeding counseling (IFC) sessions were offered to HIV pregnant women by the same team of counselors from April 2008 to December 2012. Counseling content was promoting either exclusive breastfeeding (EBF) or exclusive formula feeding (EFF) prior to 2010. Later on, versus EBF+ antiretroviral (ARV) drug given either to the mother or the infant or EFF was the gold standard. Mixed feeding was prohibited. Infants feeding were practices recorded at the first post natal visit. rate of EBF/ EFF per year and period. We included a total of 1114 live-born babies. During the five year the overall rate of EBF and EFF stood at 41% and 59% respectively. The rate of EBF/EFF was recorded as follow: varies from 25/75% in year one to 52/48% in year five(p ≤ 0.001). The rate of mixed was virtually cancelled during the same period, 3/237 (1.2%) in year one to period 1/165 (0.6%) in the latest period. In conclusion, in Yaoundé, there is a slight increase in breastfeeding rate among HIV exposed infants during the first two months of life. Further investigations are required to confirm this tendency and analyze the new features of breastfeeding practices.

ObjectivesTo document patients’ and healthcare professionals’ (HCP) experiences with hepatitis B virus (HBV) and hepatitis C virus (HCV) diagnosis and care, as well as consequences of these infections on patients’ life trajectories in Cameroon, an endemic country in sub-Saharan Africa.DesignQualitative sociological study combining in-depth interviews and observations of medical consultations. Interviews and observations transcripts were thematically analysed according to the following themes: circumstances and perceptions surrounding hepatitis screening, counselling and disclosure, information provided by HCP on hepatitis prevention and treatment, experience of access to care and treatment, social/economic trajectories after diagnosis.SettingHIV and gastroenterology/medical services in two reference public hospitals in Yaoundé (Cameroon).Participants12 patients affected by HBV and/or HCV (co-infected or not with HIV), 14 HCP, 14 state and international stakeholders.FindingsMany patients are screened for HBV and HCV at a time of great emotional and economic vulnerability. The information and counselling delivered after diagnosis is limited and patients report feeling alone, distressed and unprepared to cope with their infection. After screening positive, patients struggle with out-of-pocket expenditures related to the large number of tests prescribed by physicians to assess disease stage and to decide whether treatment is needed. These costs are so exorbitant that many decide against clinical and biological follow-up. For those who do pay, the consequences on their social and economic life trajectories are catastrophic.ConclusionLarge out-of-pocket expenditures related to biological follow-up and treatment pose a real challenge to receiving appropriate care. Free or reasonably priced access to hepatitis B and C treatments can only be effective and efficient at reducing the hepatitis disease burden if the screening algorithm and the whole pretherapeutic assessment package are simplified, standardised and subsidised by comprehensive national policies orientated towards universal healthcare.