Browsing by Author "Gyang, F.N."
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Item Aflatoxin Contamination of Cassava Flour (Kokonte) Processed By Traditional Methods in Ghana(University of Ghana, 1978-12) Lokko, P.G.; Gyang, F.N.; Kordylas, M.J.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyAflatoxin contamination of cassava flour (kokonte) bought in the markets of Accra has been investigated. A survey of the methods of production and of processing of the cassava chips was conducted to determine the sources of contamination in the production of the flour. Samples of the flour were analysed for aflatoxin contamination and concentrations using Thin Layer Chromatography (T.L .C.). Known levels of aflatoxin in kokonte flour samples were fed to weanling rats to determine the effects on the rats. Serum alkaline phosphatase levels were determined in the serum samples of the individual rats. The study revealed that:- (1) Three types of kokonte flour are sold at the markets of Accra and these are named according to their colours. There are red, black and white kokonte types. (2) Methods used in the processing of the cassava chips exposed the fresh roots to mould growth and hence to aflatoxin contamination. (3) Twenty-two percent of the kokonte flour samples bought from the market were found to contain aflatoxin. The mean aflatoxin concentration was calculated to be 867pg/kg. (4) There were reduced rates of growth in the rats fed on aflatoxin-contaminated diets over a period of 25 days and their food intake was also found to have reduced when compared with those of the control group. (5) The rats on aflatoxin-contaminated diets had fatty livers and there was an evidence of a growth on one of the livers. (6) Serum alkaline phosphatase levels in rats fed aflatoxin-contaminated diets were found to be higher than those observed for the rats on control diets.Item Antiplasmodial activity of extracts of tridax procumbens and phyllanthus amarus in in vitro plasmodium falciparum culture systems(Ghana Medical Journal, 2011) Appiah-Opong, R.; Nyarko, A.K.; Dodoo, D.; Gyang, F.N.; Koram, K.A.; Ayisi, N.K.Background Aqueous extracts of Tridax procumbens (TP) (Compositae) and Phyllanthus amarus (PA) (Euphorbiaceae) are used in traditional medicine in Ghana to treat malaria. Previous studies have demonstrated the anti-trypanosoma, anti-bacterial and anti-HIV effects of TP and PA. Objective To assess the antiplasmodial activity of extracts of TP and PA. Method Aqueous extracts of TP and PA were prepared. A portion of each was freeze-dried and the remaining extracted sequentially with ethyl acetate and chloroform. Ethanolic extracts were also prepared. The antiplasmodial activity of the extracts was assessed with the 3H-hypoxanthine assay using chloroquine-resistant (Dd2) Plasmodium falciparum parasites. Chloroquine was used as the reference drug. The modified tetrazolium-based colorimetric assay was also used to evaluate the red blood cell (RBC)-protective/antiplasmodial activities and cytotoxicities of the extracts. Results Results showed that TP and PA have antiplasmodial activities. The aqueous and ethanolic extracts of PA were the most active, yielding EC50 values of 34.9µg/ml and 31.2µg/ml, respectively in the tetrazolium-based assay. The TP and PA produced and IC50 values of 24.8µg/ml and 11.7µg/ml, respectively in the hypoxanthine assay. Protection of human RBCs against P. falciparum damage by the extracts highly correlated with their antiplasmodial activities. None of the extracts, within the concentration range (1.9–500µg/ml) studied produced any overt toxicity to human RBCs. Conclusion The results indicate that both PA and TP have activities against chloroquine-resistant P. falciparum (Dd2) parasites. The antiplasmodial principles extracted into water and ethanol but not chloroform or ethyl acetate.Item Antiplasmodial Activity of Medicinal Plant Preparations T610 and S076 Using Plasmodium Falciparum in Vitro Culture System(University of Ghana, 2001-08) Appiah-Opong, R.; Gyang, F.N.; Nyarko, A.K.; Dodoo, D.; University of Ghana, College of Humanities, School of Arts, Department of Philosophy and ClassicsSome traditional medical practitioners use decoctions of the plants Tridax procumbens and Phyllanthus amarus, separately, to treat malaria in Ghana. These plants have however, not been investigated scientifically to establish their antimalarial activities. In this study, inhibition of chloroquine-resistant Plasmodium falciparum uptake o f 3H-hypoxanthine was used as an in vitro assay to assess the antiplasmodial activities of aqueous, ethanolic, chloroform and ethyl acetate extracts of Tridax procumbens and Phyllanthus amarus. Chloroquine was used as a reference antimalarial drug. Cytotoxicities of the extracts to red blood cells were also investigated. Furthermore, the aqueous extracts of the plants were evaluated for haem polymerisation inhibitory activity. The results show that high concentrations of chloroquine inhibited the uptake of 3Hhypoxanthine by Plasmodium falciparum, confirming the chloroquine-resistant nature of the parasites used. Both plant extracts also demonstrated antiplasmodial activity against the chloroquine resistant plasmodial parasites. Among the various extracts, the lowest 50% inhibitory concentrations (IC50) of 24.8 and 11.7 |ig/ml corresponded to the aqueous and ethanolic extracts, respectively, of Phyllanthus amarus. For Tridax procumbens, the lowest IC50 values were 225.0 and 143.4 |J.g/ml for the ethanolic and aqueous extracts, respectively. Unlike chloroquine, none of the extracts inhibited haem polymerisation. Within the concentration range used, the least cytotoxicity to RBCs was observed in the aqueous extracts of both plants, the ethanolic extract of Phyllanthus amarus and the ethyl acetate extract of Tridax procumbens. These results suggest that the aqueous and ethanolic extracts of both plants were more effective as antiplasmodial preparations than the other extracts.Item Complement-Mediated Destruction of Red Blood Cells in Children with Plasmodium Falciparum Malaria(University of Ghana, 2001-09) Helegbe, G.K.; Akanmori, B.D.; Kurtzals, J.A.L.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyA total of 484 children aged between 1 -10 years who reported at the emergency unit of the Department of Child Health, Korle Bu Teaching Hospital with clinical malaria were recruited for this study. The children were categorized into four main groups of clinical malaria namely, severe malaria anaemia (SA), cerebral malaria (CM), uncomplicated malaria (UM) and intravascular haemolysis, or bloody urine (IVH). The aim of the study was to determine the role of complement activation in the pathogenesis of malaria anaemia, including intravascular haemolysis. The Coombs test or Direct antiglobulin Test (DAT) was used to detect the binding of C3d alone, IgG alone or both to erythrocytes of P. falciparum malaria patients as well as healthy or asymptomatically infected children (CC). Of the 484 samples tested, 131(27%) were positive for DAT. Out of the 131 DAT positive samples, 115/131 (87%) were positive for C3d alone whiles a small proportion was positive for either IgG alone or both (p<0.05). The results showed that 25/52 (48.1%) of the SA (mean Hb= 4.3g/dl), 23/31 (74.2%) of the IVH (mean Hb=6.1g/dl), 7/25 (28.0%) of the UM (mean Hb=9.0g/dl) and 15/35 (42.8%) of the CM patients (mean Hb=7.3g/dl) were DAT positive. The differences between SA and IVH on one hand and UM on the other for C3d binding were highly significant (p<0.05) suggesting a role for C3d binding and the consequential elimination or destruction of erythrocytes as a cause of the anaemia associated with falciparum malaria. Interestingly, 90% of the DAT positive samples were from children below the ages of five years with mean ages of 3.3 and 3.9 years for SA and IVH cases respectively, confirming that younger children rely on complement activation in response to malaria.Item Diagnostic Potential of Extant Antischjstosoma Genus-Specific Monoclonal Antibodies(University of Ghana, 2001-09) Sefah, K.; Bosompem, M.K.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences,Department of Biochemistry, Cell and Molecular BiologyThe suitability o f five Schistosoma genus-specific monoclonal antibodies (MoAbs) (Sh3/34.10, Sh3/38.2, Sh4/14.3, Sh5/32.30 and Sh5/34.10) in detecting schistosome antigens in infected human and cattle was evaluated. These antibodies were employed in various diagnostic assays to diagnose human and animal schistosomiasis. Extant MoAb secreting hybridoma cells were first propagated in culture to produce the MoAbs. The culture supernatants containing secreted antibodies were analysed by immunodiffusion and the isotypes o f the immunoglobulins shown to be IgM (Sh3/34.10, Sh3/38.2, Sh5/32.30 and Sh5/34.10) and IgGl (Sh4/14.3). Gel purified fractions o f the MoAbs were utilised in developing dipstick ELISA and micro-plate ELISA in diagnosing schistosomiasis. Also, the suitability o f the indirect immunoflourescent Antibody Test (IFAT) was employed to demonstrate anti-schistosoma antibodies in the blood of infected cattle. Three o f the antibodies (Sh3/38.2, Sh4/14.3, Sh5/32.30) showed no cross-reactivity with Plasmodium falciparum circum-sporozoite protein (CSP) and crude antigen extract of P. falciparum. However Sh3/34.10 and Sh5/34.10 reacted with the crude antigen extract o f P. falciparum at high antibody concentrations even though the reactivity was abrogated at higher antibody titres. In human schistosomiasis, the diagnostic potential o f the MoAbs in detecting schistosome antigens were assessed alongside microscopy and the standard Sh2/15.F urinary schistosomiasis dipstick ELISA developed by researchers at the NMIMR. Out of 74 human subjects from a schistosomiasis endemic area screened for urinary schistosomiasis, 81.1% were microscopically positive for S. haematobium eggs whilst the standard dipstick assay gave prevalence estimate o f 87.3%. The sensitivity of this assay was 100% whereas the specificity was 64.7% compared with microscopy as the gold standard test. Dipstick assays utilizing the individual Schistosoma genus-specific monoclonal antibodies estimated prevalences o f urinary schistosomiasis between 48.6 and 58.1%. The sensitivities of the assays were however lower (60.0-71.1%) compared with microscopy as the gold standard test. Nonetheless, each of the antibodies showed a high specificity o f 100% in detecting S. haematobium urinary antigens. The Schistosoma genus-specific antibodies performed similarly when utilized in dipstick to detect S. mansoni infections. Two assays (IFAT and MoAb-based plate ELISA) were developed to diagnose animal schistosomiasis in cattle. The sensitivities o f these assays compared well with microscopy. In determining the prevalence of S. bovis, microscopy gave a prevalence of 53.1% compared with 50.0% determined by IFAT. Micro- plate based ELISA utilizing different Schistosoma genus-specific MoAbs estimated prevalence of S. bovis between 46.9% and 50.0%. These assays were sensitive (ranging from 88.2-94.1%) compared with microscopy as the gold standard test and the specificity was each 100%. In view o f the limitations of the microscopical approach the assays provided alternative diagnostic tool in detecting animal schistosomiasis in cattle. The study also demonstrated 3.1% (1/32) prevalence of S. indicum in mixed infection with S. bovis by microscopy. Eleven other cattle parasites eggs were demonstrated by microscopy with prevalence ranging from 3.1-21.9%. There was no evidence o f cross-reactivity between the antigens of these parasites and the Schistosoma genus-specific MoAbs utilised. This study revealed the diagnostic potentials o f the Schistosoma genus-specific MoAbs in detecting schistosome antigens in both humans and cattle. The development of Schistosoma genus-specific MoAb-based dipstick ELISA for diagnosing schistosomiasis is promising.Item Effects of Plasmodium Falciparum Infection on Monocyte and Neutrophil Function: A Basis for Increased Destruction of Unparasitized Erythrocytes(University of Ghana, 2001-12) Awandare, G.A.; Akanmori, B.D.; Kurtzals, J.A.L.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyIt has become certain that partof the haemolytic componentof the anaemia of Plasmodium falciparum malaria results from increased removal of unparasitized red blood cells. There have been several reports of associations between positive Coombs’ DAT and anaemia, and also of observations of unparasitized erythrocytes in monocytes of patients with P. falciparum infections. Perturbations in cytokine balance have also been blamed for reduced red cell survival as well as for defective erythropoiesis. This study sought to ascertain to what extent increase in monocyte and neutrophil function and the general inflammatory response to P. falciparum infections contribute to the anaemia of malaria. Neutrophil phagocytic activity, monocytes surface expression of HLA-DR and FcγRIII, and plasma levels of IL-10, TNF-α, IL- 8, neopterin, MIP-lα and MIP-1β were compared among groups of children with sesvere P. falciparum malaria anaemia (SA), others with other forms of malaria (cerebral, CM or uncomplicated, UM) and healthy or asymptomatic controls (AC). Phagocytic activity was measured as ability of neutrophils to take up fluorescent latex particles. All groups of children with symptomatic malaria showed higher neutrophil phagocytic activity than the control group (p<0.005). Further, among the children with symptomatic malaria, children in the SA group showed a higher phagocytic activity than the others (SA vs. CM, p=0.029; SA vs. UM, p=0.002). There was a marked reduction in monocyte expression of HLA-DR in all groups of patients compared to controls (p<0.001), but differences among patient groups were not significant. Plasma levels of all cytokines measured were not significantly different in the SA group compared to other groups of patients (p>0.05), but were markedly elevated in all patient groups compared to controls (p<0.05).Item G-PROTEIN MEDIATED SIGNAL TRANSDUCTION IN SACCHAROMYCES CEREVISIAE(University of Ghana, 1995-09) Dzudzor, B.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyYeast mating type locus gene alpha2 (MATa2), Yeast G protein complementing gene ( YGC1) and minichromosome maintenance gene (M C M 1) have been identified by isolation of plasmids that are able to complementor suppress a gpa1::HIS3 mutation. MATa2 and YGC1 rescue both MATa and MATa-gpa1: HIS3 haploid cell types whereas MCM1 complements only MATa gpal::HIS3 cell type. MATa2 is known to be a general repressor and a determinant of both haploid and diploid cell types. MCM1 is known to be a general transcriptional activator. YGC1 has not been characterised, hence its function or mode of action is not previously known. G protein alpha subunit (GPA1) is a yeast G protein a subunit that negatively controls the budding yeast pheromone signal transduction pathway. Disruption of GPA1 results in constitutive arrestof the signal pathway that leads to cell cycle arrest at the early G1 phase of the cell cycle. Both Southern analysis and sequencing showed that MATa2, YGC1, MCM 1 have no homology to GPA1. Disruption of MATa2 (that is mata2::URA3) leads to constitutive arrest of the cell cycle at the G 1 phase. MATa2 also has no sequence homology to GPA 2, the other G protein a subunit in yeast, known to be involved in cAMP pathway in yeast. It has been shown here that MATa2 rescues gpal::HIS3 cells even in single copy, centromere plasmids. Mating efficiency is largely reduced in cells kept alive with MATa2. MATa2 does not have the pheromone response elements (PREs) common to the STE genes (whose disruption leads to insensitivity to mating factors). The plasmid TGC was also constructed and used in creation of the yeast haploid strains LG1 and LG2. This was an attempt to screen a mammalian cDNA library for possible analogs of GPA1. These strains were used to isolate two mammalian analogs that complement the gpa1::HIS3 mutation. The results indicate that MATa2, YGC1 and MCM1 are components or modulate component(s) of the signaling pathway. It also showed that MATa2 is even a more potent negative regulator of the signaling pathway than GPA1, since overexpression is not a prerequisite for negatively regulating the pathway. MATa2 does not belong to the G protein family since it has no GTP/GDP binding and/or exchange domains.Item Inter-Subject Variability in the Activation of Proguanil to the Active Cycloguanil in Ghanaians(University of Ghana, 1997-07) Kudzi, W.; Gyang, F.N.; Ofori-Adjei, D.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyOne hundred and thirty-two healthy Ghanaian volunteers were randomly selected and the activation of the anti-malarial drug proguanil (PG) to the active metabolite cycloguanil (CG) was evaluated in them. These volunteers were made up of 16.7% females and 83.3% males. The volunteers were phenotyped either as extensive metabolisers (EMs) or poor metabolisers (PMs) by measuring the proguanil/cycloguanil ratio in their urine following a single dose of the pro-drug. One hundred and twenty-six subjects (97 %) were EMs while 6 subjects (3%) were PMs. The pharmacokinetic parameters of proguanil were not significantly different between 5 EM and 2 PM subjects, although the PM did show a higher plasma proguanil concentration after distribution phase and a longer elimination half-life. Cycloguanil characteristics were not different between the groups as was expected. The prevalence of 3 % of PM phenotype of proguanil metabolism in Ghanaians is comparable to results obtained in Caucasians 36%, but differ from what was obtained in Kenya (35%). This finding suggests a lesser variability of proguanil metabolism in Ghanaians. The maximum average plasma cycloguanil concentration of 93.4ng/ml obtained for the PMs in this study also showed that the metabolite concentrations achieved would be effective against many strains of P. Falciparum.Item Methionine Metabolism in Filarial Worms(University of Ghana, 1980-09) Acquaah, R.A.; Oduro, K.K.; Jaffe, J.J.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyAdult filariae apparently lack the vitamin BI2-dependent and -independent methyltransferases for the de novo synthesis of methionine and seem to meet their requirement of this amino acid from an exogenous source and the activity of S-adenosylmethionine(AdoMet):homocysteine S-methyltransferase The properties of filarial AdoMet:homocysteine methyl transferase were similar to the analogous microbial enzyme. However, adult filariae possess the enzymatic capability to metabolize methionine to cyst(e)ine. When incubated in the presence of L-{CH3-14C} methionine to induce them to synthesise AdoMet, adult Dirofilaria immitis incorporated the radiolabel into phospholipid and protein fractions. The significance of filarial methionine metabolism especially with regard to its suitability as a potential target for antifilarial chemotherapy is discussed.Item Preliminary report on levels of ascorbic acid in the urine before and after loading with ascorbic acid in Ghanaians(Ghana Medical Journal, 1963) Gyang, F.N.Item Screening of the efficacy of some commonly used antibiotics in Ghana(Research Journal of Microbiology, 2009) Helegbe, G.K.; Anyidoho, L.Y.; Gyang, F.N.The objective of this study was to screen some commonly used antibiotics in Ghana for their efficacy in treating diseases so as to select sensitive organisms that can be used to design an assay in assessing their biological activity. The disc susceptibility test was used to screen stock antibiotics such as ampicilline, chloramphenicol, kanamycin and penicillin based antibiotics from different manufacturers (both local and foreign) which were obtained from different pharmacy shops against some bacteria species such as Salmonella typhi, Staphyloccus auresus and six strains of Escherichia coli. It was observed that both stock and field antibiotics (Antibiotics obtained from pharmacy shops for study) zone of inhibition were similar and compared with literature values. J916 (an E. coli isolate) and Salmonella typhi were found to be less sensitive to the penicillin-based antibiotics similar to literature values for both stock and pharmacy shop samples. This study revealed that the antibiotics produced by local and foreign pharmaceutical companies appear to be effective. In as much as this study demonstrate that, local and foreign pharmaceutical industries appear to be producing quality drugs, further studies are needed to substantiate this claim observed by this study, which was on a small scale. © 2009 Academic Journals Inc.Item Severe Malaria-The Role of Regulatory Cytokines(University of Ghana, 1999-09) Hodo, P.K.; Akanmori, B.D.; Gyang, F.N.; Kurtzals, J.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyAn anti-inflammatory cytokine, interleukin 10 (IL-10) suppresses T-helper 1 cells (Th1) route and enhances the Th2 route in mice by boosting the antibody response. The present work studied the effect of exogenous IL-10 in the system of BALB/C mice during the development severe anaemia. BALB/C mice developed severe anaemia within 2-3 weeks after inoculation with 106 parasitised RBCs (pRBCs) intraperitoneally. BALB/C mice treated with recombinant IL-10 developed patent parasitaemia of 7% on day 7-post inoculation as compared to 10.5% in controls. Nevertheless, there was no significant difference between the two groups haematologically (parasitaemia P>0.01, haemoglobin levels P>0.01, reticulocytosis P>0.01 and in hematocrit values P> 0.01). There was generally a positive correlation between anaemia and the parasite count and reticulocytosis, but negative correlation with haemoglobin levels and the hematocrit levels measured. Cytokine levels in vivo and in vitro were determined using the ELISA technique. The endogenous IL-10 measured was higher in the IL-10 treated than the controls. However there was no difference statistically between the mortality of the two groups, though it appeared to be slower in the IL-10 treated BALB/C mice. Also, there was no significant difference between the TNF-α measured in both sera and the spleen cell culture supernatants of the two groups. IgG and IgM were measured by means of Immunoflourescence Antibody Test (IFAT) and using whole blood stages of the parasites as antigens. The role of immunoglobulin in erythrophagocytosis was observed because there was enhanced erythrophagocytosis between the 7th and 12th day, that was when lgG2a recorded the highest peak value in both test and control mice. On the other hand, lgG3 recorded low levels with a significant increase in TNF-α during the same period. The use of mitogen in vitro showed that activation of T cells results in the production of cytokines.