المقالات العلمية – كلية الطب

Permanent URI for this collectionhttps://repository.neelain.edu.sd/handle/123456789/4594

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Start date: 1990

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    The Impact of the Use of Impregnated Curtains on Antibody Responses Againstplasmodium falciparumand on Complexity of Infecting Parasite Populations
    (A Bolad, 2003-08-01) A Bolad;
    Read 'The Impact of the Use of Impregnated Curtains on Antibody Responses AgainstPlasmodium falciparumand on Complexity of Infecting Parasite Populations' on Ovid Insights.
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    Antibodies to the Plasmodium falciparum antigen Pf332 inhibit parasite growth in vitro on their own and in cooperation with monocytes
    (Wenner-Grens institut för experimentell biologi, 2004) AK Bolad, L Xu; K Berzins
    Protective immunity against Plasmodium falciparum may be obtained after repeated exposure to infection. Several studies indicate that immunity against the blood stages of the P. Falciparum infection is mainly antibody mediated. Protective antibodies may act either on their own, mediate antibody-dependent phagocytosis and/or cell-mediated neutralization of parasites. This thesis describes several aspects of humoral immune responses to P. falciparum infection in individuals of different age groups, different genetic background and with different degrees of malaria exposure. Several target antigens for antibody-mediated inhibition of parasite growth or invasion have been identified. One such antigen is Pf332, which appears on the surface of parasitized erythrocytes at late trophozoite and schizont stage. This surface exposure makes the antigen a possible target for opsonizing antibodies. We optimized an in vitro assay for studying cellmediated parasite neutralization in the presence of Pf332-reactive antibodies. Our data demonstrate that, Pf332 specific antibodies are able to inhibit parasite growth on their own and in cooperation with human monocytes. The P. falciparum parasites have evolved several mechanisms to evade the host neutralizing immune responses. In this thesis, we show that freshly isolated P. falciparum parasites from children living in a malaria endemic area of Burkina Faso were less sensitive for growth inhibition in vitro by autologous immunoglobulins (Ig) compared with heterologous ones. Analyses of two consecutive isolates taken 14 days apart, with regard to genotypes and sensitivity to growth inhibition in vitro, did not give any clear-cut indications on possible mechanisms leading to a reduced inhibitory activity in autologous parasite/antibody combinations. The frequent presence of persisting parasite clones in asymptomatic children indicates that the parasite possesses as yet undefined mechanisms to evade neutralizing immune responses. Transmission reducing measures such insecticide treated nets (ITNs) have been shown to be effective in reducing morbidity and mortality from malaria. However, concerns have been raised that ITNs usage could affect the acquisition of malaria immunity. We studied the effect of the use of insecticide treated curtains (ITC) on anti-malarial immune responses of children living in villages with ITC since birth. The use of ITC did neither affect the levels of parasite neutralizing immune responses nor the multiplicity of infection. These results indicate that the use of ITC does not interfere with the acquisition of anti-malarial immunity in children living in a malaria hyperendemic area. There is substantial evidence that the African Fulani tribe is markedly less susceptible to malaria infection compared to other sympatrically living ethnic tribes. We investigated the isotypic humoral responses against P. falciparum asexual blood stages in different ethnic groups living in sympatry in two countries exhibiting different malaria transmission intensities, Burkina Faso and Mali. We observed higher levels of the total malaria-specific-IgG and its cytophilic subclasses in individuals of the Fulani tribe as compared to non-Fulani individuals. Fulani individuals also showed higher levels of antibodies to measles antigen, indicating that the intertribal differences are not specific for malaria and might reflect a generally activated immune system in the Fulani.
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    Antibody responses in Plasmodium falciparum malaria and their relation to protection against the disease
    (Wenner-Grens institut för experimentell biologi, 2004) Ahmed Kamal Bolad
    Protective immunity against Plasmodium falciparum may be obtained after repeated exposure to infection. Several studies indicate that immunity against the blood stages of the P. Falciparum infection is mainly antibody mediated. Protective antibodies may act either on their own, mediate antibody-dependent phagocytosis and/or cell-mediated neutralization of parasites. This thesis describes several aspects of humoral immune responses to P. falciparum infection in individuals of different age groups, different genetic background and with different degrees of malaria exposure. Several target antigens for antibody-mediated inhibition of parasite growth or invasion have been identified. One such antigen is Pf332, which appears on the surface of parasitized erythrocytes at late trophozoite and schizont stage. This surface exposure makes the antigen a possible target for opsonizing antibodies. We optimized an in vitro assay for studying cellmediated parasite neutralization in the presence of Pf332-reactive antibodies. Our data demonstrate that, Pf332 specific antibodies are able to inhibit parasite growth on their own and in cooperation with human monocytes. The P. falciparum parasites have evolved several mechanisms to evade the host neutralizing immune responses. In this thesis, we show that freshly isolated P. falciparum parasites from children living in a malaria endemic area of Burkina Faso were less sensitive for growth inhibition in vitro by autologous immunoglobulins (Ig) compared with heterologous ones. Analyses of two consecutive isolates taken 14 days apart, with regard to genotypes and sensitivity to growth inhibition in vitro, did not give any clear-cut indications on possible mechanisms leading to a reduced inhibitory activity in autologous parasite/antibody combinations. The frequent presence of persisting parasite clones in asymptomatic children indicates that the parasite possesses as yet undefined mechanisms to evade neutralizing immune responses. Transmission reducing measures such insecticide treated nets (ITNs) have been shown to be effective in reducing morbidity and mortality from malaria. However, concerns have been raised that ITNs usage could affect the acquisition of malaria immunity. We studied the effect of the use of insecticide treated curtains (ITC) on anti-malarial immune responses of children living in villages with ITC since birth. The use of ITC did neither affect the levels of parasite neutralizing immune responses nor the multiplicity of infection. These results indicate that the use of ITC does not interfere with the acquisition of anti-malarial immunity in children living in a malaria hyperendemic area. There is substantial evidence that the African Fulani tribe is markedly less susceptible to malaria infection compared to other sympatrically living ethnic tribes. We investigated the isotypic humoral responses against P. falciparum asexual blood stages in different ethnic groups living in sympatry in two countries exhibiting different malaria transmission intensities, Burkina Faso and Mali. We observed higher levels of the total malaria-specific-IgG and its cytophilic subclasses in individuals of the Fulani tribe as compared to non-Fulani individuals. Fulani individuals also showed higher levels of antibodies to measles antigen, indicating that the intertribal differences are not specific for malaria and might reflect a generally activated immune system in the Fulani.
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    Distinct interethnic differences in IgG class/subclass and IgM antibody responses to malaria antigens but not in IgG responses to non-malarial antigens in sympatric tribes living in West Africa
    (Scandinavian Journal of Immunology, 2005) Ahmed Bolad
    The well-established relative resistance to malaria observed in the Fulani as compared with other sympatric tribes in West Africa has been attributed to their higher levels of serum immunoglobulin (Ig) G antibodies to malarial antigens. In this study, we confirm and extend the previous findings by analyses of the levels of IgM, IgG and IgG subclasses of anti-malarial antibodies in asymptomatic individuals of different sympatric tribes in Burkina Faso (Fulani/Mossi) and Mali (Fulani/Dogon). The Fulani showed significantly higher median concentrations of anti-malarial IgG and IgM antibodies than the sympatric tribes at both locations. Although the overall subclass pattern of antibodies did not differ between the tribes, with IgG1 and IgG3 as dominant, the Fulani showed consistently significantly higher levels of these subclasses as compared with those of the non-Fulani individuals. No significant differences were seen in the levels of total IgG between the tribes, but the Fulani showed significantly higher levels of total IgM than their neighbours in both countries. While the antibody levels to some nonmalarial antigens showed the same pattern of differences seen for antibody levels to malaria antigens, no significant such differences were seen with antibodies to other nonmalarial antigens. In conclusion, our results show that the Fulani in two different countries show higher levels of anti-malarial antibodies than sympatric tribes, and this appears not to be a reflection of a general hyper-reactivity in the Fulani.
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    Comparison of Rheumatoid Factor and anti-Cyclic-Citrullinated protein antibodies for the Diagnosis of rheumatic arthritis in Khartoum, Sudan
    (Al Neelain Medical Research Centre, 2008) Ahmed Bolad, Shaaban Khudair; Mohammed Abbas, Mowahib Al Edressy
    Background: The objective of the current study was to determine the sensitivity and specificity of anti-Cyclic-Citrullinated protein antibodies (anti-CCP antibodies) as compared to that of Rheumatoid Factor (RF) in diagnosing patients with rheumatoid arthritis (RA) Methodology Fifty six samples were collected from Sudanese patients (46 females, 9 males) with rheumatic diseases who visited the rheumatology clinic ElRibat Hospital, Khartoum, Sudan. Titers of RF and anti-CCP antibodies of each patient were recorded. Sensitivity and specificity of the test were evaluated using ELISA as the gold standard method. Results The sensitivity of (RF) test (41/56) was 73.2% whereas the sensitivity of Anti CCP test (34/56) was 60.7%. The specificity of RF test (44/56) was 78.6%, whereas the specificity of Anti CCP test (54/56) was 96.4%. Conclusions The combination of anti-CCP and RF tests provides nearly 100% and thus could be helpful in the differential diagnosis of RA and other rheumatic diseases Comparison of Rheumatoid Factor and anti-Cyclic-Citrullinated protein antibodies for the Diagnosis of rheumatic arthritis in Khartoum, Sudan. Available from: https://www.researchgate.net/publication/271014292_Comparison_of_Rheumatoid_Factor_and_anti-Cyclic-Citrullinated_protein_antibodies_for_the_Diagnosis_of_rheumatic_arthritis_in_Khartoum_Sudan [accessed Oct 08 2017].
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    Rheumatoid arthritis and anti-CCP
    (Al Neelain Medical Research Centre, 2011) Ahmed Bolad, Yousif Osman; Shaaban Khudair
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    Diagnostic value of Autoantibodies to GAD65 and IA-2 in Patients with Latent Autoimmune Diabetes in Adult (LADA)
    (Omdurman Islamic University, 2011) Ahmed Bolad, Razan Abdelmageed; Mustafa Khidir Elnimeiri
    Background: Latent autoimmune diabetes in adults (LADA) accounts for 11% of all cases of diabetes and often misdiagnosed as type 2diabetes. LADA resembles type 1diabetes and shares common physiological characteristics of type 1 but it does not affect children and has been classified distinctly as being separate from juvenile diabetes. Autoantibodies against glutamic acid decarboxylase 65 (GADA) and tyrosine phosphatase (IA-2) are found frequently in patients with LADA. The presence of these autoantibodies in LADA predicts inevitable β cell failure and poor response to oral hypoglycemic therapy i.e., patients with LADA do not respond to oral hypoglycemic therapy. Objective: To determine an immunological marker to diagnose patients not responding to oral hypoglycemic therapy. Patients and methods: A facility-based cross sectional study was conducted in Jabbir Abu Eliz Diabetes Center, located at Khartoum 2. Venous blood samples were obtained from the study patients. They were divided into three groups, group1 included 27 diabetic patients treated with insulin, group2 included 15 diabetic patients of type 2 diabetes as controls, and group3 included 15 newly diagnosed patients older than 35 years at onset of diabetes. A standardized pre-tested administered questionnaire was used for data collection and the collected data were analyzed. Results: Males encountered in the study were 28 (49.1%). On patient recently diagnosed to have type 2 diabetes mellitus (T2DM) was positive for autoantibodies to GDA/IA-2. These autoantibodies were also positive in 15 patients with diabetes mellitus type 1 (T1DM) Conclusions: Autoimmune diagnostics is of particular importance in adults to discriminate between type 1 and type 2 diabetes and to assess the diagnosis of latent autoimmune diabetes in adults. The current study results revealed that autoantibodies to GAD/IA-2 are good marker for diagnosis of latent onset DM type 1. On the other hand, data indicate that the vast majority of cases of type 1 diabetes may be considered as immune-mediated, that multiple autoantibody to GAD/IA-2 analysis are of prognostic value to predict complications e.g., retinopathy. The current study recommends using of anti-GAD/IA-2 antibodies as marker for diagnosis of latent autoimmune diabetes in adults (LADA) who are not responding to oral hypoglycemic and may be at risk for getting complications. On the other hand, the study recommends using of anti-GAD/IA-2 antibodies for prognosis of the clinical progression of diabetes type 1 for prediction of insulin dependence.