Browsing by Author "Thuita, J.K."
Now showing 1 - 6 of 6
- Results Per Page
- Sort Options
Item Chemotherapy of Second Stage Human African Trypanosomiasis: Comparison between the Parenteral Oiamidine OB829 and Its Oral Prodrug OB868 in Vervet Monkeys(2015) Thuita, J.K.; Wolf, K.K.; Murilla, G.A.; Bridges, S.A.; Boykin, W.D.; Mutuku, N.J.; Liu, Q.; Jones, K.S.; Gem, O.C.; Ching, S.; Tidwell, R.; Wang, Z.M.; Pain, M.F.; Brun, R.; Kenya Trypanosomiasis Research Institute; Philippe Büscher, Institute of Tropical Medicine, BELGIUM; Kenya Agricultural Research InstituteHuman African trypanosomiasis (HAT, sleeping sickness) ranks among the most neglected tropical diseases based on limited availability of drugs that are safe and efficacious, particularly against the second stage (central nervous system [CNS]) of infection. In response to this largely unmet need for new treatments, the Consortium for Parasitic Drug Development developed novel parenteral diamidines and corresponding oral prodrugs that have shown cure of a murine model of second stage HAT. As a rationale for selection of one of these compounds for further development, the pharmacokinetics and efficacy of intramuscular (IM) active diamidine 2,5-bis(5-amidino-2-pyridyl)furan (DB829; CPD-0802) and oral prodrug2,5-bis[5-(N-methoxyamidino)-2-pyridyl]furan (DB868) were compared in the vervet monkey model of second stage HAT. Treatment was initiated 28 days post-infection of monkeys with T. b. rhodesiense KETRI 2537. Results showed that IM DB829 at 5 mg/kg/day for 5 consecutive days, 5 mg/kg/day every other day for 5 doses, or 2.5 mg/kg/day for 5 consecutive days cured all monkeys (5/5). Oral DB868 was less successful, with no cures (0/2) at 3 mg/kg/day for 10 days and cure rates of 1/4 at 10 mg/kg/day for 10 days and 20 mg/kg/day for 10 days; in total, only 2/10 monkeys were cured with DB868 dose regimens. The geometric mean plasma Cmax of IM DB829 at 5 mg/kg following the last of 5 doses was 25-fold greater than that after 10 daily oral doses of DB868 at 20 mg/kg. These data suggest that the active diamidine DB829, administered IM, should be considered for further development as a potential new treatmeItem Comparative evaluation of anticoagulatory activity of ethylenediamine tetra-acetic acid (EDTA) and heparin for haematological analysis(2010) Kibugi, J.K.; Muchiri, M.W.; Mbugua, N.; Mwangi, J.N.; Thuita, J.K.; Kenya Trypanosomiasis Research Institute; Kenya Research Institute Trypanosomiasis Research Centre(KARI - TRC), Kenya Socio Economics and Biromantic DivisionSample collection for haematological analysis requires use of anticoagulant, the two commonly used in trypanosomiasis research being ethylenediamine tetra-acetic acid and heparin. Since these are known to have different modes of action (Lewis, 200 I), it is important to ascertain whether they can be used alternatively. Further, Swiss White mouse has been used in research involving disease pathogenesis and trials of new drugs (Kibugu et al., 2009, Thuita et al., 2008). Since handling methods are important for accurate haematological results, appropriate blood sampling and processing techniques need to be employed. The small body size of the mouse is probably a limitation to blood sample collection. The aim of the present study was to evaluate the anticoagulatory efficacy of ethylenediamine tetra-acetic acid and heparin for electronic cell counting, and develop a suitable blood handling procedure for laboratory mice.Item Comparative pathogenicity of Trypanosoma brucei rhodesiense strains in Swiss white mice and Mastomys natalensis rats(Kenya Agricultural Research Institute, 1927) Muchiri, M.W.; Ndung'u, K.; Kibugu, J.K.; Thuita, J.K.; Gitonga, P.K.; Ngae, G.N.; Mdachi, R.E.; Kagira, J.M.; Kenya Agricultural and Livestock Research Organization (KALRO), Biotechnology Research Institute (BioRI), P. O. Box 362, Kikuyu, Кепуа; Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Kenya; Kenya Food Crop Research Institute, P. O. Box 30148, Nairobi, KenyaWe evaluated Mastomys natelensis rat as an animal model for Rhodesian sleeping sickness, Parasitaemia, clinical and pathological characteristics induced by T. b. rhodesiense isolates, KETRI 3439, 3622 and 3637 were compared in Mastomys rats and Swiss white mice. Each isolate was intra-peritonially injected in mice and rat groups (n-12) at 1x 10º trypanosomes/0.2 ml. Pre-patent period (PP) range for KETRI 3439 and KETRI 3622-groups was 3-6 days for mice and 4-5 days for rats while for KETRI 3637-infected mice. and rats was 5-9 and 4-12 days, respectively. Pairwise comparison between PP of mice and rats separately infected with either isolate showed no significant difference (p>0.05). The PP's of KETRI 3637-infected mice were significantly (p>0.01) longer than those infected with KETRI 3439 or KETRI 3622, a trend also observed in rats. The second parasitaemic wave was more prominent in mice. Clinical signs included body weakness, dyspnoea, peri-orbital oedema and extreme emaciation which were more common in rats. Survival time for KETRI 3439 and 3622-infected groups was significantly (p<0.05) longer in mice than rats but similar in KETRI 3637-infected groups. Inflammatory lesions were more severe in rats than mice. All mice and KETRI 3622-infected rats had splenomegaly, organ congestion with rats additionally showing prominent lymphadenopathy. KETRI 3439-infected rats showed hemorrhagic pneumonia, enteritis with moderate splenomegaly and lymphadenopathy. KETRI 3637-infected rats had the most severe lesions characterized by prominent splenomegaly, lymphadenopathy, hepatomegaly, enlarged adrenal glands, organ congestion, generalized oedemas, gastroenteritis, pneumonia and brain congestion. KETRI 3637- infected Mastomys is a suitable model for studying pathophysiology of HAT.Item A device for restraining mice and confining tsetse flies during trypanosome infection transmission experiments(2013) Ndung’u, K.; Kibugu, J.K.; Gitonga, P.K.; Thuita, J.K.; Auma, J.E.; Gitonga, S.K.; Murilla, G.A.Chemical (anaesthesia) and manual techniques are commonly used to restrain mice during vector-mediated parasite transmission experiments in the laboratory. Chemical restraint may interfere with natural fly vector–mouse interactions and therefore potentially affect the outcome of transmission experiments. Conversely, manual restraint is labour-intensive and exposes laboratory animals to excessive restraining-related discomfort. We report development of a mouse restraining device (Infectra®-kit) that allows essential transmission studies to be carried out with minimal human manipulation and without the need for anaesthesia. Infectra®-kit can be used as a single unit for restraining one mouse or as eight-assembled units, thus significantly improving efficiency of a single operator in comparison to manual restraint. The kit was validated by comparing feeding success in tsetse flies fed on mice restrained using Infectra®-kit (Group I) to those manually restrained (Group II). The mean ± SE % feeding success was 75.0 ± 8.2% and 82.1 ± 8.2% for tsetse flies in Groups I and II respectively. Statistical analysis using two sample t-test showed no significant difference between the two groups at p ≤ 0.05, indicating that Infectra®-kit as a restraining device was as good as the conventional manual restraint method. The main benefits of using Infectra®-kit for transmission studies therefore include reduction of man-hours and animal restraining-related discomfort. In addition, the risk of accidental injury to laboratory personnel by either mice or tsetse flies is minimized, which is an important consideration when working with zoonotic parasites.Item A device for restraining mice and confining tsetse-flies during trypanosome infection transmission experiments(2013) Ndung’u, K.; Kibugu, J.K; Gitonga, P. K.; Thuita, J.K. ; Auma, J.E.; Gitonga, S.K.; Gitonga, S. K.; Murilla, G.A; Kenya Agricultural Research Institute (KARI), Kenya. kariukindungu36@yahoo.comChemical (anaesthesia) and manual techniques are commonly used to restrain mice during vector mediated parasite transmission experiments in the laboratory. Chemical restraint may interfere with natural fly vector-mouse interactions and therefore potentially affect the outcome of transmission experiments. Conversely, manual restraint is labour-intensive and exposes laboratory animals to excessive restraining-related discomfort. We report development of a mouse restraining device (Infectra"-kit) that allows essential transmission studies to be carried out with minimal human manipulation and without the need for anaesthesia. Infectra®-kit can be used as a single unit for restraining one mouse or as eight-assembled units, thus significantly improving efficiency of a single operator in comparison to manual restraint. The kit was validated by comparing feeding success in tsetse flies fed on mice restrained using Infectra®-kit (Group I) to those manually restrained (Group II). The mean ± SE % feeding success was 75.0 ± 8.2% and 82.1 ± 8.2% for tsetse flies in Groups I and II respectively. Statistical analysis using two sample I-test showed no significant difference between the two groups at p ~ 0.05, indicating that Infectra®-kit as a restraining device was as good as the conventional manual restraint method. The main benefits of using Infectra®-kit for transmission studies therefore include reduction of man-hours and animal restraining-related discomfort. In addition, the risk of accidental injury to laboratory personnel by either mice or tsetse flies is minimized, which is an important consideration when working with zoonotic parasites.Item Use of TrypTectCIAA T to determine the effectiveness of treatment of Trypanosoma brucei r/lOdesiense infections in vervet monkeys (ChLorocebus aethiops) and man(2010) Karanja, S.M. ; Ngaira, J.M.; Thuita, J.K.; Ngotho, M.; Gichuki, C.W.; ; Kenya Trypanosomiasis Research Institute; Jomo Kenyatta University of Agriculture and Technology (JKUAT), Biochemistry, Kenya, Kenya Agricultural Research Institute, Trypanosomiasis Research Centre (KARI-TRC); UNDP/World Bank/WHOThe vervet monkey (Chlorocebus aethiops) model of sleeping sickness was used to evaluate the effectiveness of TrypTectCIATT in assessing the success of trypanocidal therapy. A retrospective study was therefore conducted on sera collected from monkeys infected with Trypanosoma brucei rhodesiense and treated either curatively with melarsoprol or sub-curatively with diminazene aceturate. In the human survey, 440 sera collected from 96 human patients were tested. These patients were treated with either surname or melarsoprol depending on the stage of the disease. An extra 56 parasitologically positive pre-treatment samples were also tested to aid in determination of the test sensitivity. Results indicated that between 21-28 days post-infection, the test detected trypanosomal antigens in 84.2% (16119) of animal samples that were parasitologically positive by the hematocnt centrifugation technique (RCT). In curatively treated animals, 77, 8% (7/9) exhibited positive reaction up to 9 months post-treatment. One animal was positive for trypanosomal antigens for the entire 12 months while one was a non-reactor from the sub-curatively treated group, 80% (8110) were detected positive for the entire 12 months while, 2 animals were non-reactors.In the human survey, 3 patterns of antigen profiles were observed. In some patients, there was fluctuation of antigen levels throughout the 12 months follow-up period. In others, antigens were detected for the entire 12 months but in decreasing levels. The last group was that of patients with antigens decreasing at different rates to undetectable levels at 12 months post-treatment. The presence of trypanosome positive but antigen negative samples during the study raises a few questions with regards to the sensitivity of the test. It is however evident that the test was able to detect trypanosomal antigens in over 80% of positive monkey and human serum samples. Consequently, TrypTectCIATT may be an important additional tool reduction of the follow-up period and determination of success of chemotherapy in sleeping sickness.
