Research Articles

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A research article reports the results of original research, assesses its contribution to the body of knowledge in a given area, and is published in a peer-reviewed scholarly journal. The faculty publications through published and on-going articles/researches are captured in this community

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Now showing 1 - 10 of 19
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    Detection of antigens and antibodies in the urine of humans with plasmodium falciparum malaria.
    (Journal of Clinical Microbiology, 1991) Rodriguez-del Valle, M.; Quakyi, I.A.; Amuesi, J.; Quaye, J.T.; Nkrumah, F.K.; Taylor, D.W.
    Humans infected with Plasmodium falciparum frequently have elevated levels of proteins in their urine, but it is unclear if any of these proteins are parasite antigens or antimalarial antibodies. To resolve this question, urine samples from malaria patients and controls living in Thailand and Ghana were evaluated. Urine samples from 85% of the patients had elevated protein levels and contained proteins with M(r)s ranging from <29,000 to >224,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Antisera were produced against urine from infected and control subjects. Antisera raised against infected, but not control, urine were positive by indirect immunofluorescence on P. falciparum parasites and immunoprecipitated approximately 12 unique bands from extracts of parasites metabolically labeled with 35S-methionine. These data suggest that a variety of P. falciparum antigens are released into urine during acute infection. It is also likely that anti-P. falciparum antibodies are present in the urine of malaria patients because samples from these patients, but not controls, were positive in indirect immunofluorescence assays and immunoprecipitated at least 19 P. falciparum antigens from extracts of metabolically labeled parasites. The detection of malarial antigens and antibodies in urine may lead to a new approach for the diagnosis of malaria.
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    Survival of burkitt's lymphoma patients in Ghana
    (British Journal of Cancer, 1971) Wosornu, J.L.; Nkrumah, F.K.; Perkins, I.V.
    Of 141 suspected cases of Burkitt's lymphoma referred from all over Ghana between November 1965 and June 30, 1969, the diagnosis of Burkitt's lymphoma was confirmed histologically in 60. This report deals with survival of all 50 treated and evaluable cases. The overall estimated long term survival rate was 38·5% calculated actuarially. It was 63·2% for Stage I (10 of 18); 20·0% for Stage II (2 of 10); and 25·4% for Stages III and IV combined (3 of 22), thus confirming the value of staging as a rough guide to prognosis. Six Stage I patients who died all had large tumors. These results have been compared with a similar study by Morrow et al. (1967) from Uganda.
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    Lack of association between maternal antibody and protection of African infants from malaria infection.
    (Infection and Immunity, 2000) Riley, E.M.; Wagner, G.E.; Ofori, M.F.; Wheeler, J.G.; Akanmori, B.D.; Tetteh, K.; McGuinness, D.; Bennett, S.; Nkrumah, F.K.; Anders, R.F.; Koram, K.A.
    Maternally derived antibodies are believed to protect infants against infection, but there is little direct evidence for a protective role of passively acquired antibodies against malaria. A longitudinal study of malaria infection in 143 infants was conducted in a region of southern Ghana where Plasmodium falciparum is endemic. Infants born in the high-transmission season were less likely to become infected in the first 20 weeks of life than children born in the low-transmission season. Plasma, obtained at birth, was tested for immunoglobulin G (IgG) and IgG subclasses to P. falciparum schizonts and recombinant circumsporozoite antigen, MSP-1 19, MSP-2, AMA-1, and Pf155 (also called ring-infected erytrocyte surface antigen). Antibody levels at birth were not associated with resistance to malaria infection. On the contrary, antibodies at birth were positively associated with infection, indicating that high levels of maternally derived antibodies represent a marker for intensity of exposure to malaria infection in infants. However, all five children who experienced high-density infections (>100 parasites/?l of blood) were seronegative for MSP-1 19 at the time of infection.
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    A three-year prospective study of 137 cases of acute leukaemia in Zimbabwe.
    (Central African Journal of Medicine, 1992) Paul, B.; Mukiibi, J.M.; Mandisodza, A.; Levy, L.; Nkrumah, F.K.
    We studied 137 cases of acute leukaemia seen between December 1985 and November 1988, using traditional staining techniques together with cytochemistry and in cases of probable acute lymphoblastic leukaemia (Sudan Black negative) by immunophenotyping. Not all tests were carried out in every case (some cases of ALL could only be classified as T or non-T). Paediatric group (age less than or equal to 14 yrs): 75 cases--acute lymphoblastic leukaemia 52, acute myeloid leukaemia 18, acute undifferentiated leukaemia 5. Peak incidence in 5-9 year group. Male:Female ratio = 1.7:1. acute myeloid leukaemia was associated with chloromas in 2 cases (11 pc). Adult group: 62 cases--acute lymphoblastic leukaemia 23, acute myeloid leukaemia 36 and acute undifferentiated leukaemia 3. Peak incidence in 50-54 age group. Male:Female ratio = 1:1.2. Acute lymphoblastic leukaemia subtypes (all ages) T 16, Common 20, Null 12, 'non-T' 16, B cell 0, untyped 11. 69 pc were of L2 morphology. In T-ALL, 11 had thymomas and Male:Female ratio = 15:1. Male:Female ratio for 'non-T' = 1.5:1. Acute myeloid leukaemia subtypes (all ages) M1 3, M2 8, M3 14, M4 19, M5 8, M6 2, M7 1. Overall incidence of acute leukaemia appears increased at 0.91 per 100,000 per annum from previous studies in Zimbabwe. Common ALL (mean age = 13 years) is an emerging problem and now outnumbers T-ALL (mean age = 10 years). This may be related to a general improvement in living standards and health in Zimbabwe.
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    Incidence of symptomatic and asymptomatic plasmodium falciparum infection following curative therapy in adult residents of northern Ghana.
    (American Journal of Tropical Medicine and Hygiene, 2001) Owusu-Agyei, S.; Koram, K.A.; Baird, J.K.; Utz, G.C.; Binka, F.N.; Nkrumah, F.K.; Fryauff, D.J.; Hoffman, S.L.
    Adult residents of holoendemic malaria regions in Africa have a naturally acquired immunity (NAI) to malaria that renders them more resistant to new infections, limits parasitemia, and reduces the frequency and severity of illness. Given such attributes, it is not clear how one might evaluate drug or vaccine efficacy in adults without serious confounding. To determine symptomatic and asymptomatic malaria attack rates in adults of northern Ghana, 197 men and women underwent curative therapy for any pre-existing malaria infections at the start of the high transmission (wet) season. They were monitored for first parasitemia and first clinical episode of infection by Plasmodium falciparum over a 20-week period (May-October 1996). The cumulative incidence of primary infection by P. falciparum was 0.98 and incidence density of infection was calculated to be 7.0 cases/person-year. Symptoms were reported by 19.5% of the individuals at the time of first recurrent parasitemia. Incidence of infection, parasite density, and the frequency of symptoms were comparable in males and females. The results suggest that NAI did not provide these adults with significant defense against rapid re-infection and suggest that this population-infection design could serve to demonstrate the efficacy of a drug or vaccine in preventing parasitemia.
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    Characteristics of severe anemia and its association with malaria in young children of the Kassena-Nankana district of northern Ghana.
    (American Journal of Tropical Medicine and Hygiene, 2002) Owusu-Agyei, S.; Fryauff, D.J.; Chandramohan, D.; Koram, K.A.; Binka, F.N.; Nkrumah, F.K.; Utz, G.C.; Hoffman, S.L.
    Severe anemia is thought to be the principal underlying cause of malaria death in areas of intense seasonal malaria transmission such as the Kassena-Nankana District of northern Ghana. Factors associated with severe anemia in young children, 6-24 months old, were elucidated by analyzing results of 2 malaria-associated anemia surveys (1996, 2000), separated by 4 years, but conducted in the same community and at the same seasonal time point. Age-adjusted comparison confirmed that the proportion of severely anemic children and overall mean hemoglobin (Hb) levels in the November 2000 sample were significantly improved over those of the 1996 sample (17.5 versus 26.4%, P = 0.03; Hb 7.5 versus 6.9 g/dL, P = 0.002). Weight-for-age Z-scores also indicated a significant improvement in the 2000 sample (-1.93 versus -2.20, P < 0.05). Independently, each survey identified statistically significant associations between severe anemia and age, parasite rate, fever, and sex. Relative to children with Hb > or = 6.0 g/dL, those with severe anemia (Hb < 6.0 g/dL) were older, more frequently parasitemic (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.08-2.35), more often febrile (OR, 2.44; 95% CI, 1.71-3.48), and predominantly male (OR, 1.50; 95% CI, 1.05-2.13). An association was identified in both surveys between severe anemia and residence in the northern part of the district, but no clear link was observed in relation to irrigation. Blood transfusions, a likely surrogate index of severe anemia in young children, followed a distinct seasonal pattern. Evidence suggests that dramatic peaks and troughs of severe anemia are regular and possibly predictable events that may be used to gauge the health and survival of young children in this area.
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    Randomized trial of sulfamethoxazole + trimethoprim versus procaine penicillin for the outpatient treatment of childhood pneumonia in Zimbabwe.
    (Bulletin of the World Health Organization, 1990) Keeley, D.J.; Nkrumah, F.K.; Kapuyanyika, C.
    Reported are the results of a randomized trial of sulfamethoxazole + trimethoprim versus procaine penicillin for the outpatient treatment of pneumonia in 614 children aged 3 months to 12 years at primary health care clinics in Chitungwiza, a large town near Harare, Zimbabwe. Diagnosis and treatment were carried out by nurses, without medical supervision. The presence of lower respiratory tract infection that required antibiotics was diagnosed on the basis of a recent history of a cough and the presence of a respiratory rate of greater than 50 per minute. Patients were followed up by a research nurse with minimal drop-out losses. Referred children were examined and assessed by a doctor at the Chitungwiza General Hospital. Of the study children, 65 (11%) were referred to hospital, but only 8 (1.3%) had pneumonia that required a change in the treatment (5 in the sulfamethoxazole + trimethoprim group and 3 in the procaine penicillin group). There were no significant differences in outcome between the two treatment groups. One child, who had evidence of infection with human immunodeficiency virus (HIV), died. Sulfamethoxazole + trimethoprim and procaine penicillin were highly and equally effective for the outpatient treatment of children who had been clinically diagnosed to have pneumonia by primary health care workers.
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    Measles epidemic in Harare, Zimbabwe, despite high measles immunization coverage rates.
    (Bulletin of the World Health Organization, 1991) Kambarami, R.A.; Nathoo, K.J.; Nkrumah, F.K.; Pirie, D.J.
    Despite rapidly increasing measles immunization coverage in Harare City, measles remains endemic, and regular outbreaks occur. The most recent occurred in 1988, when the measles immunization coverage was 83%. We have carried out a retrospective study of the clinical and epidemiological features of this outbreak to assess whether the present immunization policy needs to be changed. Of 4357 cases of measles seen at primary health care centres and hospitals in Harare during the outbreak, 1399 (32%) were severe or involved complications that required hospital admission. The peak incidence occurred among under-2-year-olds, followed by that among 5-7-year-olds. Poor nutritional status was significantly more frequent among children who were hospitalized and among those who died. A total 59% of all cases aged 9-59 months had documented evidence of measles immunization. The most frequent complications, which occurred most often among under-5-year-olds, were diarrhoea with dehydration, pneumonia, laryngotracheobronchitis, and convulsions, which together affected 56% of hospitalized cases. The hospital case fatality rate was low (1.43%). In Harare, measles transmission remains a problem, despite high measles immunization coverage rates; the failure rate for the standard Schwarz measles vaccine also appears to be high. There is a need to reduce the number of measles cases among under-9-month-olds and young children. Further studies into alternative measles vaccines and schedules are required.
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    Specific T-cell recognition of the merozoite proteins rhoptry-associated protein 1 and erythrocyte-binding antigen 1 of plasmodium falciparum.
    (Infection and Immunity, 1993) Jakobsen, P.H.; Hviid, L.; Theander, T.G.; Afare, E.A.; Ridley, R.G.; Heegaard, P.M.H.; Stuber, D.; Daalsgard, K.; Nkrumah, F.K.
    The merozoite proteins merozoite surface protein 1 (MSP-1) and rhoptry- associated protein 1 (RAP-1) and synthetic peptides containing sequences of MSP-1, RAP-1, and erythrocyte-binding antigen 1, induced in vitro proliferative responses of lymphocytes collected from Ghanaian blood donors living in an area with a high rate of transmission of malaria. Lymphocytes from a large proportion of the Ghanaian blood donors proliferated in response to the RAP-1 peptide, unlike those of Danish control blood donors, indicating that this sequence contains a malaria-specific T-cell epitope broadly recognized by individuals living in an area with a high transmission rate of malaria. Most of the donor plasma samples tested contained immunoglobulin G (IgG) and IgM antibodies recognizing the merozoite proteins, while only a minority showed high IgG reactivity to the synthetic peptides.
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    Rapid reemergence of T cells into peripheral circulation following treatment of severe and uncomplicated plasmodium falciparum malaria.
    (Infection and Immunity, 1997) Hviid, L.; Kurtzhals, J.A.L.; Goka, B.Q.; Oliver-Commey, J.O.; Nkrumah, F.K.; Theander, T.G.
    Frequencies and absolute numbers of peripheral T-cell subsets were monitored closely following acute Plasmodium falciparum malaria in 22 Ghanaian children from an area of hyperendemicity for seasonal malaria transmission. The children presented with cerebral or uncomplicated malaria (CM or UM, respectively) or with severe malarial anemia. For all patients the frequencies and absolute numbers of peripheral T cells were lower than normal during the acute stage of disease. This lowering was most pronounced in the CM group and least pronounced in the UM group. Of particular interest, the CM patients showed markedly reduced frequencies of CD41 cells, the number of which also normalized slower than in the other clinical groups. In all patients, the T-cell frequencies gradually approached normal values after the initiation of therapy, whereas the absolute numbers rapidly reverted from lower than normal to higher than normal before returning to steady-state levels. Furthermore, the initially reduced T-cell surface density of the T-cell receptor/CD3 complex, which rapidly normalized, was a general finding for all three clinical groups, suggesting a state of peripheral T-cell hyporesponsiveness during acute malaria. The data presented suggest a rapid therapyinduced reemergence of T cells that had been temporarily removed from the peripheral circulation as a consequence of the malaria attack and that the degree of the disease-induced T-cell reallocation correlates with disease severity.