[Ageing and chronic diseases in Senegal. A comparison between rural (Ferlo) and urban (Dakar) populations]

The objectives of this study were: to compare the prevalence of hypertension, overweight and obesity in rural (Ferlo) and urban (Dakar) Senegalese populations aged 50 and over. The survey was conducted on individuals aged 50 and older living in the rural area (N=478) and in the urban area (N=220). We have collected data about age, gender, marital status, education level, and knowledge, treatment of hypertension, height, weight and blood pressure. We have observed that overweight and obesity were more prevalent in the urban area (Dakar) than in the rural one (Ferlo). The risk of overweight or obesity decreased when age increased, and women had weight problems more often than men. The prevalence of arterial hypertension was lower in rural area (55.86%) than in Dakar (66.36%), but increased at an older age. However, the logistic regression showed that these increased proportion of hypertension in Dakar is linked to the more important proportion of overweight and obese people in this area. Moreover, rates of knowledge, treatment and control of hypertension are particularly low in the rural area of Senegal. In conclusion, age-associated diseases should be better managed in Senegal, particularly in rural areas.

[Arterial hypertension in Dakar: Prevalence, awareness, treatment, and control]

The aim of this study was to determine prevalence, awareness, treatment, and control of hypertension, and its risk factors in Dakar. Six hundred people aged 20 and older, living in the city of Dakar were interviewed. This sample was constructed using the combined quota method in order to strive to representativeness of the target population. Prevalence of hypertension was 27.50%. Quarter of those suffering from high blood pressure were aware of their problem, and among the latter, 61% said they were on treatment. However, of these, only 32% had controlled arterial blood pressure, that is less than 6% of those suffering from hypertension. Two factors were associated with hypertension, awareness, and treatment: age and the frequency of doctor visits. These results indicate that hypertension already constitutes a major health concern in the Senegalese capital. Detection can be considerably improved given that only a quarter of the hypertensives are aware of this problem. Compliance with treatments also appears particularly problematic. Public health policies should be quickly set up to minimize the consequences of this emerging burden.

Hypertension prevalence, awareness, treatment and control in Dakar (Senegal)

The prediction of risk profile trends associated with non-communicable diseases in developing countries is among the greatest global health challenges. The aim of this study is to estimate prevalence, awareness, treatment and control of hypertension in Dakar (Senegal). This study was carried out between January and June 2009 on a population sample of 600 individuals living in the department of Dakar. This sample was constructed using the quota method in order to strive for representativeness. Sociodemographic characteristics, hypertension, hypertension awareness, treatment and control, and body mass index of individuals were collected during face-to-face interviews. Statistical analyses used were χ2-tests and binary logistic regressions. Prevalence of hypertension was 27.50%. Prevalence of awareness, treatment and control among hypertensives were 27.88%, 16.97% and 5.45%, respectively. Logistic regression showed that the prevalence, awareness and treatment of hypertension increased with increasing age. Overweight and obese subjects were more often hypertensive but did not differ from others in awareness and treatment. This could be linked to the social valorization of stoutness in West Africa, which explains that excess weight is not perceived as a risk factor for hypertension. In conclusion, given the very low rates of awareness, treatment and control in our sample, developing strategies for averting a hypertension epidemic must be a priority objective.

Prevalence, awareness, treatment and control of hypertension among adults 50 years and older in Dakar, Senegal

Background

Older adults are disproportionately affected by hypertension, which is an established risk factor for cardiovascular disease. Despite these facts, no study on the prevalence, awareness, treatment and control on arterial hypertension in Senegal has been conducted, specifically among elderly people.

Methods

Five hundred people aged 50 years and older, living in the city of Dakar were interviewed. This sample was constructed using the combined quota method in order to strive for representativeness of the target population.

Results

Prevalence of hypertension was 65.4% in our sample. Half of those suffering from high blood pressure were aware of their problem and among the latter, 70% said they were on treatment. However, of these, only 17% had controlled arterial blood pressure. The only factor associated with awareness, treatment and control of hypertension was the frequency of doctor visits.

Conclusion

Improving follow-up health checks of older adults are necessary to limit the consequences of hypertension in Dakar.

Prevalence of obesity in Dakar

The present study is to our knowledge the first to evaluate the prevalence of obesity among both men and women in Dakar. It was carried out on a sample of 600 dwellers of the Senegalese capital. The prevalence of general obesity is 8.3%, and that of overweight is 22.3%. The underweight rate remains high, given that 12.3% of the adults in this sample show a body mass index (BMI) of <18.5 kg/m(2) . The prevalence of central obesity is 41.2% according to waist to hip ratio (WHR), and 21.2% according to waist circumference (WC). These figures mask considerable differences between men and women and between generations. For instance, women are often more obese than men, whether it is a question of general obesity (13% and 3.9% respectively) or central obesity (37.5% and 5.5% by WC respectively). Moreover, prevalence of general and central obesity rise drastically with age, irrespective of gender. Thus, in addition to combating infectious disease and undernutrition, Senegal must now face problems associated with overweight and obesity.

Role of the FYVE finger and the RUN domain for the subcellular localization of Rabip4

Rabip4 is a Rab4 effector, which possesses a RUN domain, two coiled-coil domains, and a FYVE finger. It is associated with the early endosomes and leads, in concert with Rab4, to the enlargement of endosomes, resulting in the fusion of sorting and recycling endosomes. Our goal was to characterize the role of these various domains in Rabip4 subcellular localization and their function in Chinese hamster ovary cells. Although the FYVE finger domain specifically bound phosphatidylinositol 3-phosphate and was necessary for the function of Rabip4, it was not sufficient for the protein association with membranes. Indeed a protein containing the FYVE finger and the Rab4-binding site was cytosolic, whereas the total protein was mostly associated to the membrane fraction, whether or not cells were pretreated with wortmannin. By contrast, a construct corresponding to the N-terminal end, Rabip4-(1-212), and containing the RUN domain was membrane-associated. The complete protein partitioned between the Triton X-100-insoluble and -soluble fractions and a wortmannin treatment increased the amount of the protein in the Triton X-100 fraction. Rabip4-(1-212) was totally Triton X-100-insoluble, and confocal microscopic examination showed that it labeled not only the endosomes, positive for Rabip4, but also a filamentous network with a honeycomb appearance. The Triton X-100-insoluble fraction that contains Rabip4 did not correspond to the caveolin or glycosylphosphatidylinositol-enriched lipid rafts. Rabip4 did not appear directly linked to actin but seemed associated to the actin network. We propose that the subcellular localization of the protein is primarily driven by the RUN domain to endosomal microdomains characterized by Triton X-100 insolubility and that the FYVE domain and the Rab4-binding domain then allow for the recruitment of the protein to lipophilic microdomains enriched in phosphatidylinositol 3-phosphate.

Specificities for the small G proteins ARF1 and ARF6 of the guanine nucleotide exchange factors ARNO and EFA6

ARF1 and ARF6 are distant members of the ADP-ribosylation factor (ARF) small G-protein subfamily. Their distinct cellular functions must result from specificity of interaction with different effectors and regulators, including guanine nucleotide exchange factors (GEFs). ARF nucleotide-binding site opener (ARNO), and EFA6 are analogous ARF-GEFs, both comprising a catalytic "Sec7" domain and a pleckstrin homology domain. In vivo ARNO, like ARF1, is mostly cytosolic, with minor localizations at the Golgi and plasma membrane; EFA6, like ARF6, is restricted to the plasma membrane. However, depending on conditions, ARNO appears active on ARF6 as well as on ARF1. Here we analyze the origin of these ARF-GEF selectivities. In vitro, in the presence of phospholipid membranes, ARNO activates ARF1 preferentially and ARF6 slightly, whereas EFA6 activates ARF6 exclusively; the stimulation efficiency of EFA6 on ARF6 is comparable with that of ARNO on ARF1. These selectivities are determined by the GEFs Sec7 domains alone, without the pleckstrin homology and N-terminal domains, and by the ARF core domains, without the myristoylated N-terminal helix; they are not modified upon permutation between ARF1 and ARF6 of the few amino acids that differ within the switch regions. Thus selectivity for ARF1 or ARF6 must depend on subtle folding differences between the ARFs switch regions that interact with the Sec7 domains.

Structure of Arf6-GDP suggests a basis for guanine nucleotide exchange factors specificity

Arf6 is an isoform of Arf that localizes at the periphery of the cell where it has an essential role in endocytotic pathways. Its function does not overlap with that of Arf1, although the two proteins share approximately 70% sequence identity and they have switch regions, whose conformation depends on the nature of the guanine nucleotide, with almost identical sequences. The crystal structure of Arf6-GDP at 2.3 A shows that it has a conformation similar to that of Arf1-GDP, which cannot bind membranes with high affinity. Significantly, the switch regions of Arf6 deviate by 2-5 A from those of Arf1. These differences are a consequence of the shorter N-terminal linker of Arf6 and of discrete sequence changes between Arf6 and Arf1. Mutational analysis shows that one of the positions which differs between Arf1 and Arf6 affects the configuration of the nucleotide binding site and thus the nucleotide binding properties of the Arf variant. Altogether, our results provide a structural basis for understanding how Arf1 and Arf6 can be distinguished by their guanine nucleotide exchange factors and suggest a model for the nucleotide/membrane cycle of Arf6.

Binding of the PH and polybasic C-terminal domains of ARNO to phosphoinositides and to acidic lipids

The activity on ARF of the guanine nucleotide exchange factor ARNO depends on its membrane recruitment, induced by binding of its PH domain to phosphoinositides. A polycationic C-terminal extension to the PH domain might also contribute to its specific binding to phosphatidylinositol 4,5-bisphosphate [(4,5)PIP2] and to phosphatidylinositol 3,4,5-trisphosphate [(3,4,5)PIP3], and to ionic binding to other acidic lipids. We have analyzed in vitro the relative contributions to phospholipid binding of the PH domain and C-terminal extension by cosedimentation of "PH+C domain" and "nominal PH domain" protein constructs including or not including the polycationic C-terminus, with sucrose-loaded unilamellar vesicles made of equal proportions of the neutral lipids phosphatidylcholine and phosphatidylethanolamine, and supplemented or not with 30% acidic phosphatidylserine (PS) and 2% of various phosphoinositides. Binding was measured as a function of the vesicle concentration and of the medium ionic strength. Both proteins bound with higher affinity to (3,4,5)PIP3 than to (4,5)PIP2, the selectivity for (3,4,5)PIP3 being highest for the nominal PH domain. We observed also a clear selectivity of (3,4,5)PIP3 over (4,5)PIP2 for stimulating the activity of ARNO on ARF with vesicles containing 10% PS and 1% PIP2 or PIP3. Our data suggest that the PH domain provides the specific phosphoinositide binding site and some unspecific ionic interaction with acidic PS, whereas the polybasic C domain contributes to binding mainly by unspecific ionic interactions vith PS. Phosphorylation by protein kinase C of a serine in the C domain reduces the ionic affinity of the PH+C domain for PS, but does not affect the phosphoinositide specificity.

Primary sources of phosphorus and phosphates in chemical evolution

In this work we consider the role of phosphorus in chemical evolution from an interdisciplinary approach. First we briefly review the presence of this element in different cosmic sites, such as massive stellar cores, circumstellar and interstellar clouds, meteorites, lunar and Martian samples, interplanetary dust particles, cometary dust and planetary atmospheres. Thus we illustrate the fact that phosphorus seems to be, at the same time, scarce and ubiquitous in the solar system. Afterwards, by comparing the phosphorus content of our planet's main reservoirs with the amount of cometary and meteoritic matter captured by the primitive Earth, we conclude that comets may have provided a primary source for phosphorus compounds of prebiotic interest. Finally, we make a number of proposals aimed to gain observational supporting evidence to the above conclusion and other suggestions made in the article.