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Henry Tabel - One of the best experts on this subject based on the ideXlab platform.
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Trypanosoma Congolense Infections: Induced Nitric Oxide Inhibits Parasite Growth In Vivo.
Journal of parasitology research, 2011Co-Authors: Guojian Wei, Wanling Pan, Henry TabelAbstract:Wild-type (WT) C57BL/6 mice infected intraperitoneally with Trypanosoma Congolense survive for more than 30 days. C57BL/6 mice deficient in inducible nitric oxide synthase (iNOS−/−) and infected with 103 or parasites do not control the parasitemia and survive for only or days, respectively. Bloodstream trypanosomes of iNOS−/− mice infected with T. Congolense had a significantly higher ratio of organisms in the S
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Impaired Kupffer cells in highly susceptible mice infected with Trypanosoma Congolense.
Infection and immunity, 2005Co-Authors: Meiqing Shi, Guojian Wei, Wanling Pan, Henry TabelAbstract:In highly susceptible BALB/c mice infected with Trypanosoma Congolense, the total number of Kupffer cells in the liver remains constant; however, their mean size increases fivefold towards the terminal stage. About 25% of Kupffer cells undergo apoptosis. We suggest that development of an impairment of the macrophage system might be a major mechanism for inefficient elimination of trypanosomes.
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Susceptibility and resistance to Trypanosoma Congolense infections.
Microbes and infection, 2000Co-Authors: Henry Tabel, Radhey S. Kaushik, Jude E. UzonnaAbstract:Abstract We have put emphasis on recent findings in experimental Trypanosoma Congolense infections in highly susceptible BALB/c and relatively resistant C57Bl/6 mice. Based on various analyses, it has been shown that a major difference in resistance to T. Congolense infections is expressed early in infection at the macrophage level. A novel plastic-adherent Thy1.2 + suppressor lymphocyte, which in absolute synergy with a Thy 1.2 – cell exerts its suppression via interleukin-10 and interferon-γ opens up an exciting new field of research.
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Effect of different cytokines on the growth of Trypanosoma Congolense cultured under axenic conditions
Veterinary parasitology, 1997Co-Authors: Radhey S. Kaushik, Jude E. Uzonna, Henry TabelAbstract:Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Sask. S7N 5B4, Canada Received 7 June 1996; accepted 22 November 1996 Abstract We previously reported that susceptible BALB/c mice had high amounts of interleukin-4 (IL-4) and interleukin-10 (IL-10) in their plasma after infection with Trypanosoma Congolense and the levels of these cytokines decreased dramatically after berenil treatment. These observations instigated us to speculate that these cytokines might be directly affecting the growth of these parasites. Previously, it was reported that interferon gamma (IFN-y) had a growth stimulatory effect on T. brucei brucei in vitro. Although recombinant murine IL-4, IL-10 and IFN-3, used in this study were biologically active, none of these cytokines had any growth stimulatory or inhibitory effect on T. Congolense in vitro. Keywords: Trypanosoma Congolense; Cytokines; Growth; Axenic conditions 1. Introduction African trypanosomes are protozoan parasites of the blood and cause debilitating disease and death in man and domestic animals. Trypanosoma Congolense is causing severe problems in the animal industry in tropical Africa. Trypanosomes escape the host's immune defenses because of the remarkable features of antigenic variation and immunosuppression (Mansfield, 1990; Sileghem et al., 1994). In response to Trypanosomal infection, the host's immune system produces different types of antibodies and cytokines (Mansfield, 1990; Sileghem et al., 1994). Different breeds of cattle in Africa have different susceptibilities to trypanosomes. N'dama cattle * Corresponding author. Tel.: (306) 966-7215; fax: (306) 966-7244. 0304-4017/97/$17.00 Copyright © 1997 Elsevier Science B.V. All rights reserved. PH S0304-401 7(96)01 156-9
Narimantas Cenas - One of the best experts on this subject based on the ideXlab platform.
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mechanism of reduction of quinones by Trypanosoma Congolense trypanothione reductase
Biochemistry, 1994Co-Authors: David Arscott, Narimantas Cenas, Charles H. Williams, John S BlanchardAbstract:A number of quinones were analyzed as substrates for trypanothione reductase from Trypanosoma Congolense, an enzyme responsible for the protection of trypanosomes against oxidative stress. Using NADPH as substrate, the maximal rate of the steady-state reaction at pH 7.5 was between 24 and 1.6 s -1 for 11 quinone substrates. The biomolecular steady-state rate constants for quinone reduction, V/K m , ranged from 240 to 1.9×10 5 M -1 s -1 , and their logarithms exhibited a hyperbolic dependence on the one-electron-reduction potentials of the quinone substrate. The addition of NADP + stimulated these rates, with V/K m values increasing with an increasing NADP + /NADPH ratio
Andrew J. Nok - One of the best experts on this subject based on the ideXlab platform.
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Testicular and epididymal pathology in Yankasa rams experimentally infected with Trypanosoma Congolense
Asian Pacific Journal of Tropical Disease, 2014Co-Authors: Oluyinka O. Okubanjo, Victor O. Sekoni, Ologunja J. Ajanusi, Andrew J. Nok, A. A. AdeyeyeAbstract:Objective To investigate the pathological effect of experimental Trypanosoma Congolense (T. Congolense) infection on the testes and epididymis of Yankasa rams.
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A bloodstream Trypanosoma Congolense sialidase could be involved in anemia during experimental trypanosomiasis.
Journal of biochemistry, 2003Co-Authors: Andrew J. Nok, Emmanuel Oluwadare BalogunAbstract:The release of Sialic acid (SA) into the serum by Trypanosoma Congolense infected BalbC mice was investigated. A progressive increase in the level of serum SA corresponding to anemia and parasitemia was observed. At maximum parasitemia, the level of total SA from the red blood cells (RBC) dropped by about 45%. Solved polynomials revealed an association between free serum SA and RBC-SA. Positive roots of quadratics were used to predict complete cleavage of RBC-SA on day 7.01 and maximum accumulation of free serum SA on day 6.6. A steady rise in the level of serum sialidase (SD) activity and a low packed cell volume (PCV) with an increase in parasitemia were observed. Mice infused with galactose, methyl-beta-gal, lactose, mannose, or L-arabinose and challenged by intraperitoneal inoculation with Trypanosoma Congolense neither developed anemia nor secreted free SA above the control level even though there was detectable SD activity. Bloodstream Trypanosoma Congolense parasites were isolated using DEAE cellulose from heparinized blood of experimentally infected BalbC mice. The parasites were lysed with 0.2% Triton-CF 54 to release membrane bound SD. The activity of the SD was proportional to the number of parasites. The enzyme was partially purified on Q-Sepharose and Fetuin agarose columns successively. The final active fraction from the latter column was used as the partially purified SD. The enzyme had an optimum pH of 6 and was maximally active at 37 degrees C with a requirement for the divalent ions Ca(2+) and Mg(2+). The enzyme was highly specific for NeuAc5alpha2,3 lac and Methylumbelliferyl-Neu5Ac (4-MU-Neu5Ac) with K(M) values of 0.34 and 0.025 mM, respectively. It was inhibited competitively by 2,3-didehydroneuraminic acid (Neu5Ac2en) and para-nitro-phenyloxamic acid (pNPO) with inhibition binding constants K(i) of 65 and 215 micro M, respectively. In deviation from the procyclic Trypanosomal SD, it lacked trans-sialidase (TS) activity. The possible role of a secreted bloodstream Trypanosoma Congolense SD and the development of anemia in the pathogensesis of trypanosomiasis are discussed.
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Azaanthraquinone inhibits respiration and in vitro growth of long slender bloodstream forms of Trypanosoma Congolense.
Cell biochemistry and function, 2002Co-Authors: Andrew J. NokAbstract:An ethanolic extract of Mitracarpus scaber was found to possess in vitro and in vivo trypanocidal activity against Trypanosoma Congolense. At a dosage of 50 mg kg−1 day−1 in normal saline for 5 days, the extract cured Balbc mice infected with T. Congolense without any relapse. The isolated active component benz(g)isoquinoline 5,10 dione (Azaanthraquinone) (AQ) purified from the extract was found to inhibit glucose-dependent cellular respiration and glycerol-3-phosphate-dependent mitochondrial O2 assimilation of the long bloodstream forms of Trypanosoma Congolense. On account of the pattern of inhibition, the target could be the mitochondrial electron transport system composed of glyceraldehyde 3-phosphate dehydrogenase (G3PDH). The azaanthraquinone specifically inhibited the reduced coenzyme Q1-dependent O2 uptake of the mitochondria with respect to ubiquinone. The susceptible site could be due to ubiquinone redox system which links the two enzyme activities. Copyright © 2002 John Wiley & Sons, Ltd.
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Phospholipase A2 from Trypanosoma Congolense: Characterization and haematological properties
Cell biochemistry and function, 1993Co-Authors: Andrew J. Nok, A. N. Esievo, Sani Ibrahim, Agwu I. Ukoha, Christopher O. IkediobiAbstract:Phospholipase A2 was isolated from Trypanosoma Congolense and purified to electrophoretic homogeneity. The enzyme appeared to exist in a dimeric form with subunit molecular weights of 16,500 and 18,000. It had a pH optimum of 6.8. Kinetic analysis with different substrates, showed that the enzyme had exceptional specificity for 1,2,dimyristoyl-sn-phosphatidylcholine and 1,2,dioleoyl-sn-phosphatidylcholine with Km values of 1.85 x 10(-3) M and 2.12 x 10(-3) M respectively. The Arrhenius plot was linear with an activation energy of 5.8 kcal mol-1. Inhibition studies with parahydroxy-mercuribenzoate and tributyl-tin-oxide were positive thus implicating a thiol group at the catalytic site of the enzyme. The enzyme was stable to heat treatment and possessed haemolytic and anticoagulating properties.
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Modulation of the calcium pump of the kidney and testes of rats infected with Trypanosoma Congolense.
Journal of comparative pathology, 1992Co-Authors: Andrew J. Nok, K.a.n. Esievo, M.o. Ajibike, I.i. Achoba, K. Tekdek, C.e. Gimba, James Adagadzu Kagbu, Iliya S. NdamsAbstract:The activity of the CaMgATPase (Ca-pump) of the kidney and testes of Wistar rats infected with Trypanosoma Congolense was studied during the course of infection. The activity of the enzyme in both organs was found to decrease with increase in parasitaemia. The transition temperature (Tc) decreased and activation energy (Ea) of the enzyme increased with increase in parasitaemia. The relevance of the Ca-pump in the pathogenesis of trypanosomiasis is discussed.
Jude E. Uzonna - One of the best experts on this subject based on the ideXlab platform.
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Diminazene Aceturate (Berenil) Modulates the Host Cellular and Inflammatory Responses to Trypanosoma Congolense Infection
2016Co-Authors: Shiby Kuriakose, Helen M. Muleme, Chukwunonso Onyilagha, Rani Singh, Ping Jia, Jude E. UzonnaAbstract:Background: Trypanosoma Congolense are extracellular and intravascular blood parasites that cause debilitating acute or chronic disease in cattle and other domestic animals. Diminazene aceturate (Berenil) has been widely used as a chemotherapeutic agent for trypanosomiasis in livestock since 1955. As in livestock, treatment of infected highly susceptible BALB/c mice with Berenil leads to rapid control of parasitemia and survival from an otherwise lethal infection. The molecular and biochemical mechanisms of action of Berenil are still not very well defined and its effect on the host immune system has remained relatively unstudied. Here, we investigated whether Berenil has, in addition to its trypanolytic effect, a modulatory effect on the host immune response to Trypanosoma Congolense. Methodology/Principal Findings: BALB/c and C57BL/6 mice were infected intraperitoneally with T. Congolense, treated with Berenil and the expression of CD25 and FoxP3 on splenic cells was assessed directly ex vivo. In addition, serum levels and spontaneous and LPS-induced production of pro-inflammatory cytokines by splenic and hepatic CD11b+ cells were determined by ELISA. Berenil treatment significantly reduced the percentages of CD25+ cells, a concomitant reduction in the percentage of regulatory (CD4+Foxp3+) T cells and a striking reduction in serum levels of disease exacerbating pro-inflammatory cytokines including IL-6, IL-12, TNF and IFN-c. Furthermore, Berenil treatment significantly suppressed spontaneous and LPS-induced production of inflammatory cytokines by splenic and liver macrophages and significantl
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Diminazene aceturate (Berenil) modulates the host cellular and inflammatory responses to Trypanosoma Congolense infection.
PLOS ONE, 2012Co-Authors: Shiby Kuriakose, Helen M. Muleme, Chukwunonso Onyilagha, Rani Singh, Ping Jia, Jude E. UzonnaAbstract:Background Trypanosoma Congolense are extracellular and intravascular blood parasites that cause debilitating acute or chronic disease in cattle and other domestic animals. Diminazene aceturate (Berenil) has been widely used as a chemotherapeutic agent for trypanosomiasis in livestock since 1955. As in livestock, treatment of infected highly susceptible BALB/c mice with Berenil leads to rapid control of parasitemia and survival from an otherwise lethal infection. The molecular and biochemical mechanisms of action of Berenil are still not very well defined and its effect on the host immune system has remained relatively unstudied. Here, we investigated whether Berenil has, in addition to its trypanolytic effect, a modulatory effect on the host immune response to Trypanosoma Congolense.
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regulatory t cells enhance susceptibility to experimental Trypanosoma Congolense infection independent of mouse genetic background
PLOS Neglected Tropical Diseases, 2012Co-Authors: Ifeoma Okwor, Shiby Kuriakose, Chukwunonso Onyilagha, Ping Jia, Zhirong Mou, Jude E. UzonnaAbstract:Background BALB/c mice are highly susceptible while C57BL/6 are relatively resistant to experimental Trypanosoma Congolense infection. Although regulatory T cells (Tregs) have been shown to regulate the pathogenesis of experimental T. Congolense infection, their exact role remains controversial. We wished to determine whether Tregs contribute to distinct phenotypic outcomes in BALB/c and C57BL/6 mice and if so how they operate with respect to control of parasitemia and production of disease-exacerbating proinflammatory cytokines.
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Susceptibility and resistance to Trypanosoma Congolense infections.
Microbes and infection, 2000Co-Authors: Henry Tabel, Radhey S. Kaushik, Jude E. UzonnaAbstract:Abstract We have put emphasis on recent findings in experimental Trypanosoma Congolense infections in highly susceptible BALB/c and relatively resistant C57Bl/6 mice. Based on various analyses, it has been shown that a major difference in resistance to T. Congolense infections is expressed early in infection at the macrophage level. A novel plastic-adherent Thy1.2 + suppressor lymphocyte, which in absolute synergy with a Thy 1.2 – cell exerts its suppression via interleukin-10 and interferon-γ opens up an exciting new field of research.
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Effect of different cytokines on the growth of Trypanosoma Congolense cultured under axenic conditions
Veterinary parasitology, 1997Co-Authors: Radhey S. Kaushik, Jude E. Uzonna, Henry TabelAbstract:Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Sask. S7N 5B4, Canada Received 7 June 1996; accepted 22 November 1996 Abstract We previously reported that susceptible BALB/c mice had high amounts of interleukin-4 (IL-4) and interleukin-10 (IL-10) in their plasma after infection with Trypanosoma Congolense and the levels of these cytokines decreased dramatically after berenil treatment. These observations instigated us to speculate that these cytokines might be directly affecting the growth of these parasites. Previously, it was reported that interferon gamma (IFN-y) had a growth stimulatory effect on T. brucei brucei in vitro. Although recombinant murine IL-4, IL-10 and IFN-3, used in this study were biologically active, none of these cytokines had any growth stimulatory or inhibitory effect on T. Congolense in vitro. Keywords: Trypanosoma Congolense; Cytokines; Growth; Axenic conditions 1. Introduction African trypanosomes are protozoan parasites of the blood and cause debilitating disease and death in man and domestic animals. Trypanosoma Congolense is causing severe problems in the animal industry in tropical Africa. Trypanosomes escape the host's immune defenses because of the remarkable features of antigenic variation and immunosuppression (Mansfield, 1990; Sileghem et al., 1994). In response to Trypanosomal infection, the host's immune system produces different types of antibodies and cytokines (Mansfield, 1990; Sileghem et al., 1994). Different breeds of cattle in Africa have different susceptibilities to trypanosomes. N'dama cattle * Corresponding author. Tel.: (306) 966-7215; fax: (306) 966-7244. 0304-4017/97/$17.00 Copyright © 1997 Elsevier Science B.V. All rights reserved. PH S0304-401 7(96)01 156-9
David Arscott - One of the best experts on this subject based on the ideXlab platform.
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mechanism of reduction of quinones by Trypanosoma Congolense trypanothione reductase
Biochemistry, 1994Co-Authors: David Arscott, Narimantas Cenas, Charles H. Williams, John S BlanchardAbstract:A number of quinones were analyzed as substrates for trypanothione reductase from Trypanosoma Congolense, an enzyme responsible for the protection of trypanosomes against oxidative stress. Using NADPH as substrate, the maximal rate of the steady-state reaction at pH 7.5 was between 24 and 1.6 s -1 for 11 quinone substrates. The biomolecular steady-state rate constants for quinone reduction, V/K m , ranged from 240 to 1.9×10 5 M -1 s -1 , and their logarithms exhibited a hyperbolic dependence on the one-electron-reduction potentials of the quinone substrate. The addition of NADP + stimulated these rates, with V/K m values increasing with an increasing NADP + /NADPH ratio
