Browsing by Author "Duijvestein, M."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Lower Expression of TLR2 and SOCS-3 Is associated with schistosoma haematobium Infection and with lower risk for allergic reactivity in children living in a rural area in Ghana(PLoS Neglected Tropical Diseases 2(4): e227, 2008) Hartgers, F.C.; Obeng, B.B.; Kruize, Y.C.; Duijvestein, M.; de Breij, A.; Amoah, A.; Larbi, I.A.; van Ree, R.; Wilson, M.D.; Rodrigues, L.C.; Boakye, D.A.; Yazdanbakhsh, M.Background: Helminth infections are prevalent in rural areas of developing countries and have in some studies been negatively associated with allergic disorders and atopy. In this context little is known of the molecular mechanisms of modulation involved. We have characterized the innate immune responses, at the molecular level, in children according to their helminth infection status and their atopic reactivity to allergens. Methodology/Principal Findings: The mRNA expression of several genes of the innate immune system that have been associated with microbial exposure and allergy was examined in 120 school children in a rural area in Ghana. Helminth infections were common and atopy rare in the study area. The analysis of gene expression in ex vivo whole blood samples reflected the levels of corresponding proteins. Using this approach in a population of school children in whom the presence of Schistosoma haematobium infection was associated with protection from atopic reactivity, we found that the level of TLR2 and SOCS-3, genes associated with atopy in the children, were significantly downregulated by presence of S. haematobium infection. Conclusions: S. haematobium infections modulate the expression of genes of the innate immune system (TLR2 and SOCS-3); these are genes that are associated with increased allergic inflammatory processes, providing a molecular link between the negative association of this infection and atopy in rural children in Ghana.Item Lower Expression of TLR2 and SOCS-3 Is Associated with Schistosoma haematobium Infection and with Lower Risk for Allergic Reactivity in Children Living in a Rural Area in Ghana(PLOS Neglected Tropical Diseases, 2008-04) Hartger, F.C.; Obeng, B.B.; Kruize, Y.C.M.; Duijvestein, M.; De Breij, A.; Amoah, A.; Larbi, A.I.; van Ree, R.; Wilson, D.M.; Rodrigues, C.L.; Boakye, D.A.; Yazdanbakhsh, M.Background: Helminth infections are prevalent in rural areas of developing countries and have in some studies been negatively associated with allergic disorders and atopy. In this context little is known of the molecular mechanisms of modulation involved. We have characterized the innate immune responses, at the molecular level, in children according to their helminth infection status and their atopic reactivity to allergens. Methodology/Principal Findings: The mRNA expression of several genes of the innate immune system that have been associated with microbial exposure and allergy was examined in 120 school children in a rural area in Ghana. Helminth infections were common and atopy rare in the study area. The analysis of gene expression in ex vivo whole blood samples reflected the levels of corresponding proteins. Using this approach in a population of school children in whom the presence of Schistosoma haematobium infection was associated with protection from atopic reactivity, we found that the level of TLR2 and SOCS-3, genes associated with atopy in the children, were significantly downregulated by presence of S. haematobium infection. Conclusions: S. haematobium infections modulate the expression of genes of the innate immune system (TLR2 and SOCS-3); these are genes that are associated with increased allergic inflammatory processes, providing a molecular link between the negative association of this infection and atopy in rural children in Ghana.Item Prevalence of symptomatic tinea capitis and associated causative organisms in the Greater Accra Region, Ghana [7](British Journal of Dermatology, 2006-04) Hogewoning, A.A.; Duijvestein, M.; Boakye, D.; Amoah, A.S.; Obeng, B.B.; Van Der Raaij-Helmer, E.M.H.; Staats, C.C.G.; Bouwes Bavinck, J.N. et.al.Tinea capitis is a common infection among schoolchildren throughout the world.1 It is an infection of the hair shaft on the scalp, which may be caused by Trichophyton and Microsporum species. The most important causative agents are species which cause an endothrix infection, such as T. gourvilli, T. soudanense, T. tonsurans, T. violaceum and T. yaoundei, and species that cause an ectothrix infection, such as M. audouinii, M. canis and M. gypseum.2 The causative agent of tinea capitis varies with geography, socioeconomic status and time.3 Although the clinical appearance is variable, late detection and lack of treatment of this disease can result in widespread infections and, in rare cases, permanent alopecia. More knowledge about the prevalence and causative agents of tinea capitis is necessary to improve control and therapeutic measures. In order to provide information about symptomatic tinea capitis in Ghana, a cross‐sectional study was conducted by a team of three dermatologists (A.A.H., J.N.B.B., A.P.M.L.) from 31 May to 6 June 2004 with 463 schoolchildren from two public rural schools, one public urban school and one private urban school in the Greater Accra Region. The private urban school had a high socioeconomic status, while that of the three other schools was low. Specific attention was focused on clinical signs of fungal infection on the scalp (scaling, hair loss, black dots, pustules and scars). Scalp samples were taken by gentle brushing with glass slides and tweezers, and transported at room temperature to the Mycology Laboratory of the Department of Dermatology of the Leiden University Medical Centre (Leiden, the Netherlands). The specimens were examined by direct microscopic examination using 20% KOH. For the cultures modified Sabouraud's dextrose agar with chloramphenicol was used and the specimens were incubated for 28 days at 28 °C. Species identification was based on growth rate, macroscopic appearance and microscopic examination. χ 2 analyses were used to analyse the different distributions of tinea capitis among boys and girls, different age groups and the different schools. Figure 1A shows examples of symptomatic tinea capitis in the study population. Of the 463 children examined during the survey, 39 (8·4%) had clinical signs of tinea capitis (Table 1). In four of the 39 clinically suspected cases insufficient material was collected for microscopic examination and culture. Hair stumps and scales were collected from the remaining 35 patients: 27 were positive by microscopic examination and 27 cases were identified by culture.