The Association of High Prevalence of Trophozoites in Peripheral Blood with Lower Antibody Response to P. falciparum Infected Erythrocytes among Asymptomatic Children in Sudan.

Background. The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells. In this study we have examined the antibody reactivity of autologous plasma from symptomatic and asymptomatic malaria infected children against the infected erythrocytes' surface antigens using flow cytometry. Methods. Ethidium-bromide-labelled erythrocytic mature forms of P. falciparum parasites obtained from symptomatic and asymptomatic children were sequentially incubated with autologous plasma and fluorescein isothiocyanate-conjugated (FITC) antihuman IgG. Plasma antibody reactivity was detected by flow cytometry. Results. Asymptomatic children had more prevalence of trophozoites in peripheral blood (66%) compared to symptomatic children (16%), p = 0.002. The mean percentage of infected RBCs reacting with autologous sera was 89.78 among symptomatic children compared to 79.62 among asymptomatic children (p = 0.09). Moreover, the mean fluorescence intensity (MFI) in the asymptomatic was significantly higher compared to symptomatic children (p value = 0.040). Conclusion. Variant surface antigens on Plasmodium falciparum infected RBCs from symptomatic malaria children tend to be better recognized by IgG antibodies. This may suggest a role of some IgG antibodies in severity of malaria.

Replication of the association of GLT6D1 with aggressive periodontitis in a Sudanese population.

BACKGROUND: Susceptibility to aggressive periodontitis (AgP) is influenced by genetic as well as environmental factors. Studies linking gene variants to AgP have been mainly centred in developed countries with limited data from Africa. AIM: To investigate whether previously reported candidate gene associations with AgP could be replicated in a population from Sudan. METHODS: The investigation was a case-control design. Cases with AgP (n = 132) and controls (n = 136) were identified from patients attending the Periodontal Department in Khartoum Dental Hospital. Genotyping was performed using the Sequenom MassARRAY iPLEX platform. Analysis focused on gene variants with a minor allele frequency (MAF) > 25% in the Sudanese subjects that had previously been reported to be associated with AgP. RESULTS: One candidate gene rs1537415 (GLT6D1) was significantly associated with AgP, OR = 1.50 (95% CI 1.04-2.17), p = 0.0295 (increasing to p = 0.09 after correction for multiple testing). The association strengthened to OR = 1.56 (95% CI 1.15-2.16), p = 0.0042 when the controls were supplemented with data from the Hap map for the Yoruba in Ibadan (n = 147) and remained significant (p = 0.013) after correction for multiple testing. CONCLUSION: The study independently replicated the finding that rs1537415, a variant in glycosyl transferase gene GLT6D1, is associated with AgP and provided the first report of genetic associations with AgP in a Sudanese population.

Molecular Characterization of Sudanese and Southern Sudanese Chicken Breeds Using mtDNA D-Loop.

The objective of this study was to assess the genetic relationships and diversity and to estimate the amount of gene flow among the five chicken populations from Sudan and South Sudan and commercial strain of egg line White Leghorn chickens. The chicken populations were genotyped using mtDNA D-loop as a molecular marker. PCR product of the mtDNA D-loop segment was 600 bp and 14 haplotypes were identified. The neighbor-joining phylogenetic tree indicated that the indigenous Sudanese chickens can be grouped into two clades, IV and IIIa only. Median joining networks analysis showed that haplotype LBB49 has the highest frequency. The hierarchal analysis of molecular variance (AMOVA) showed that genetic variation within the population was 88.6% and the differentiation among the population was 11.4%. When the populations was redefined into two geographical zones, rich and poor Savanna, the results were fractioned into three genetic variations: between individuals within population 95.5%, between populations within the group 0.75%, and genetic variation between groups 3.75%. The pair wise F st showed high genetic difference between Betwil populations and the rest with F st ranging from 0.1492 to 0.2447. We found that there is large number of gene exchanges within the Sudanese indigenous chicken (Nm = 4.622).

Peroxiredoxin V: A candidate breast tumor marker of population specificity.

Breast and cervical cancers account for approximately 50% of all types of cancer in Sudanese women. In a previous preliminary proteomic study aimed to identify proteins that were differentially expressed between tumors and control tissues (n=24), we identified peroxiredoxin V (PrdxV) as a candidate tumor marker. Peroxiredoxins (Prdxs) are a family of multifunctional proteins that are involved in the cell protection against oxidative stress, modulation of intracellular signaling, and regulation of cell proliferation. Knockout animal models suggest that the regulation of these proteins may be a novel target for therapeutic interventions. A total of 91 tumors and 79 normal breast tissues obtained from a panel of 106 Sudanese breast cancer patients, as well as 31 paired tissue samples (tumors and controls) from Chinese cancer patients were included in this study. Tissue sections were examined using immunohistochemistry (IHC) for PrdxI, V and VI antibodies. The PrdxV mRNA pattern of expression was also investigated using in situ hybridization (ISH). The overall expression of the same Prdx family members was also examined in a panel of Chinese breast carcinoma and control samples. Statistical comparisons were performed between Prxds antibodies, and between available demographic and pathological parameters. The studied Prdxs were found to be overexpressed in both Sudanese and Chinese breast cancer and control samples. PrdxV was the only member of the Prdxs family to be significantly down-regulated in Sudanese tumor samples, with only a few cases being immunoreactive for PrdxV (11%). Significant elevation was demonstrated between tumors and controls at both the protein (using IHC) (P=0.000) and mRNA (using ISH) (P= 0.044) levels. However, the finding was more apparent and statistically significant at the protein level, suggesting the presence of post-translational modification. These findings suggest that PrdxV is a tumor marker of population specificity. However, more studies are needed to investigate the applicability of PrdxV as a marker in Sudanese breast cancer patients and its potential implications in therapy.

Host candidate gene polymorphisms and clearance of drug-resistant Plasmodium falciparum parasites.

BACKGROUND: Resistance to anti-malarial drugs is a widespread problem for control programmes for this devastating disease. Molecular tests are available for many anti-malarial drugs and are useful tools for the surveillance of drug resistance. However, the correlation of treatment outcome and molecular tests with particular parasite markers is not perfect, due in part to individuals who are able to clear genotypically drug-resistant parasites. This study aimed to identify molecular markers in the human genome that correlate with the clearance of malaria parasites after drug treatment, despite the drug resistance profile of the protozoan as predicted by molecular approaches. METHODS: 3721 samples from five African countries, which were known to contain genotypically drug resistant parasites, were analysed. These parasites were collected from patients who subsequently failed to clear their infection following drug treatment, as expected, but also from patients who successfully cleared their infections with drug-resistant parasites. 67 human polymorphisms (SNPs) on 17 chromosomes were analysed using Sequenom's mass spectrometry iPLEX gold platform, to identify regions of the human genome, which contribute to enhanced clearance of drug resistant parasites. RESULTS: An analysis of all data from the five countries revealed significant associations between the phenotype of ability to clear drug-resistant Plasmodium falciparum infection and human immune response loci common to all populations. Overall, three SNPs showed a significant association with clearance of drug-resistant parasites with odds ratios of 0.76 for SNP rs2706384 (95% CI 0.71-0.92, P = 0.005), 0.66 for SNP rs1805015 (95% CI 0.45-0.97, P = 0.03), and 0.67 for SNP rs1128127 (95% CI 0.45-0.99, P = 0.05), after adjustment for possible confounding factors. The first two SNPs (rs2706384 and rs1805015) are within loci involved in pro-inflammatory (interferon-gamma) and anti-inflammatory (IL-4) cytokine responses. The third locus encodes a protein involved in the degradation of misfolded proteins within the endoplasmic reticulum, and its role, if any, in the clearance phenotype is unclear. CONCLUSIONS: The study showed significant association of three loci in the human genome with the ability of parasite to clear drug-resistant P. falciparum in samples taken from five countries distributed across sub-Saharan Africa. Both SNP rs2706384 and SNP1805015 have previously been reported to be associated with risk of malaria infection in African populations. The loci are involved in the Th1/Th2 balance, and the association of SNPs within these genes suggests a key role for antibody in the clearance of drug-resistant parasites. It is possible that patients able to clear drug-resistant infections have an enhanced ability to control parasite growth.

Hyper-reactive Malarial Splenomegaly (HMS) in malaria endemic area in Eastern Sudan.

Hyper-reactive Malarial Splenomegaly (HMS) is massive enlargement of the spleen resulting from abnormal immune response to repeated attacks of malaria. The present study was carried out in Kassala city, Eastern Sudan where HMS is considered as highly prevalent. The objectives of this study were to determine the incidence of HMS in Eastern Sudan, and to identify basic laboratory and clinical characteristics of this condition in Sudanese patients. In the period between January and March 2004, a cross-sectional study was carried out in four health centers in Kassala city. In the current study 114 out 1010 (11%) medical cases examined were found to have enlarged spleens, 87 (9%) of them were diagnosed as HMS. Sixty-three percent of HMS cases were males and the rest were females. The mean age of HMS patients was 28 years. Clinical investigations showed that all cases suffered from abdominal pain in the upper left quadrant and all had a palpable firm spleen (10-26cm) below the costal margin. Laboratory examinations showed that 74% of the cases were anaemic and the mean white blood count for all cases was 4237cell/mL(3). Serum concentration of IgM in all subjects was above the threshold of the mean value plus 2 S.D. for 35 asymptomatic controls. In more than 70% of the HMS patients (53 individuals) the spleens were impalpable after the third month of the treatment. Our data indicate that HMS is one of the major causes of tropical splenomegaly in Eastern Sudan.

Leishmania donovani: an in vitro study of antimony-resistant amphotericin B-sensitive isolates.

Drug sensitivity of clinically antimony-unresponsive Leishmania donovani isolates from Eastern Sudan was evaluated in an in vitro culture system against sodium stibogluconate (Pentostam) and Amphotericin B. Eight isolates, six from antimony-resistant and two from clinically responsive patients were included in the study. Parasites were tested as promastigotes and four of them were selected to be tested as amastigotes using a murine macrophage-like cell line. The results indicated that the conventional promastigotes and amastigotes-screening assays did not correlate with the clinical picture of patients. In vivo unresponsiveness does not necessarily mean primary parasite resistance. Amphotericin B could be a suitable second line drug in patients unresponsive to pentostam and without concomitant diseases, if close hospital monitoring is available. Promastigotes sensitivity testing concentrations are virtually incomparable with the in vivo clinically curable doses and the amastigotes/macrophage test concentrations.