Diminazene is a drug that is commonly used in the treatment of canine babesiosis. Most of the pharmacokinetic work on diminazene has been undertaken in healthy individuals, while the influence of disease on diminazene pharmacokinetics has been investigated to a limited degree. Population pharmacokinetics allows for the investigation of factors (covariates) that influence pharmacokinetic parameters. The aim of this study was to provide a descriptive model of the population pharmacokinetics of intramuscularly administered diminazene in dogs naturally infected with Babesia canis. Thirty-nine dogs had 142 plasma samples collected. Another 56 samples from 8 healthy dogs, from a previous study, were added to the data set. Population pharmacokinetics was performed using WinNonMix® (Pharsight, Cary, NC). A one-compartment model was fitted to the data. Health status (presence or absence of babesiosis), packed cell volume (PCV), serum albumin concentrations, mental status (a marker for the severity of illness) and the presence of splenomegaly significantly influenced the population pharmacokinetics model. The PCV lost its significance when these covariates were modelled concurrently, due to its correlation to the health status. In the final model, the volume of distribution (health status and albumin) and K01 (health status) was significantly influenced by covariates. / Dissertation (MMedVet)--University of Pretoria, 2007. / Companion Animal Clinical Studies / MMedVet / Unrestricted

The aim of this thesis was to provide a picture of the trypanosomosis and drug resistance prevalence in Eastern Province of Zambia, to understand the underlying factors of drug resistance (drug use habits), to improve the diagnosis of trypanosomosis in livestock and finally, to improve the diagnosis of isometamidium resistance in T.congolense. After an introductory part where available trypanosomosis and trypanocide resistance diagnostic methods are described and discussed, the body of the thesis is divided in two main sections. In the first section are presented the results of a cross-sectional and a longitudinal epidemiological survey describing the geographical distribution of trypanosomosis cases, of resistant isolates and of cattle treated with isometamidium chloride. The results of the monitoring of unsupervised treatments of cattle with isometamidium by farmers and veterinary assistants with the Isometamidium-ELISA technique are also presented. The second section describes the development of two new diagnostic methods, the first one allowing the diagnosis of trypanosome infections with high sensitivity and specificity through semi-nested polymerase chain reaction and restriction fragment length polymorphism. This is the first report of a pan-trypanosome PCR test (a single PCR test for the diagnosis of all important pathogenic trypanosomes of cattle). The second new method that was developed allows the diagnosis of isometamidium resistant T.congolense strains by PCR-RFLP. This is the first report of a PCR based diagnostic test of trypanocide resistance in T. congolense.

This paper aimed to describe some lab and histological findings from an experimental infection of Trypanosoma (Trypanozoon) evansi Steel, 1885 (Balbiani, 1888) in rats (Rattus novergicus) belonging to the Wistar strain, testing the effectiveness of three medications. These animals were divided in 4 groups of 10 each and treated to three different chemical treatments after the detection of more than eight tripomastigotes for visual side of the blood smears at the light microscope with 1000 increase. Was tested injectable oxytetracycline 10%, benzonidazol per oss and injectable diminazene 7% while one infected and untreated group remained as control. Evaluation of treatment efficacy was performed through daily blood smears stained by Panotico Rápido® for 60 days. The rats were necropsied aiming histological examination. Treatment with diminazene was the most efficient since no parasites having significant difference (p < 0.05) between males and females of that group, which presented survive after the treatment of 14,4 days more than the males. Histological alterations findings were not specific. / Este trabalho objetivou verificar os achados laboratoriais e histológicos da infecção experimental por Trypanosoma (Trypanozoon) evansi (Steel, 1885) Balbiani, 1888, em ratos (Rattus norvegicus) da linhagem Wistar, testando a eficácia de três medicamentos. Foram utilizados 40 ratos, divididos em quatro grupos de 10 cada, sendo cada grupo composto por 5 machos e cinco fêmeas, os quais foram tratados com três quimioterápicos distintos após a detecção de parasitemia superior a oito tripomastigotas por campo visual do esfregaço sangüíneo ao microscópio de luz (1000 vezes). Testou-se oxitetraciclina 10% injetável, benzonidazol comprimidos de 100mg e aceturato de diminazeno 7% injetável comparados com um grupo controle, experimentalmente infectado, mas não tratado. As avaliações foram feitas por contagens diárias da presença de hemoparasitas em esfregaço sangüíneo, corado por Panótico Rápido®, por 60 dias. Os ratos foram necropsiados e avaliados histologicamente à procura de alterações microscópicas dos órgãos afetados. O tratamento feito com aceturato de diminazeno foi o mais eficaz no controle da parasitemia, havendo diferença significativa (p < 0.05) entre machos e fêmeas desse grupo, as quais apresentaram período de sobrevida após o tratamento de 14,4 dias superior aos machos. Histologicamente as alterações encontradas nos órgãos afetados foram inespecíficas.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of this study was to evaluate the utilization of a standard treatment with diminazene aceturate against the infection caused by T. evansi, associated to sodium selenite and vitamin E. In vitro tests showed trypanocidal effect related to the treatment with diminazene aceturate and sodium selenite, but vitamin E had no harmful effect on the trypanosomes. In vivo experiments utilized a total of 72 adult outbreed females rats, separated into 9 groups (A, B, C, D, E, F, G, H and I), 8 animals each. Group A was the uninfected group; groups B to I were infected with 0.2 mL of blood containing 106 trypanosomes. Parasitemia was estimated daily by microscopic examination of blood smears. Group B served as positive control; group C was treated with diminazene aceturate; group D with sodium selenite; group E with vitamin E; group F received an association of diminazene aceturate and sodium selenite; group G received an association of diminazene aceturate and vitamin E; group H received an association of diminazene aceturate, sodium selenite and vitamin E, and group I received an association of sodium selenite and vitamin E. Diminazene aceturate was administrated in a single dose on the 3rd day post infection (PI). Sodium selenite and vitamin E were administered at the 3rd and 23rd day PI. In vivo tests showed increase of longevity in groups treated with diminazene aceturate associated with sodium selenite (groups F and H). No difference was found between groups C and E, thus the vitamin E did not increase the efficacy of treatment against T. evansi when associated to diminazene aceturate. The curative efficacy of treatments was 37.5, 87.7, 37.7 and 75% to the groups C, F, G and H, respectively. Other treatments showed no efficacy. The sodium selenite when combined with chemotherapy may represent an alternative in the treatment of trypanosomosis. / O objetivo deste estudo foi avaliar a utilização de um tratamento padrão contra a infecção causada pelo T. evansi, baseado na utilização do aceturato de diminazeno associado ao selenito de sódio e a vitamina E. Os testes in vitro mostraram um efeito tripanocida relacionados ao tratamento com aceturato de diminazeno e selenito de sódio; contudo a vitamina E não gerou nenhum efeito nocivo sobre o tripanossomas. Experimentos in vivo utilizaram um total de 72 fêmeas adultas de ratos, separados em 9 grupos (A, B, C, D, E, F, G, H e I), com 8 animais cada grupo. O grupo A serviu como grupo não infectado; grupos de B a I foram infectados com 0,2 mL de sangue contendo 106 tripanossomas. A parasitemia foi estimada diariamente por exame microscópico de esfregaços sanguíneo. O grupo B serviu como controle positivo; grupo C, tratado com aceturato de diminazeno; grupo D, com selenito de sódio; grupo E, com vitamina E; grupo F, recebeu uma associação de aceturato de diminazeno e selenito de sódio; grupo G, associação de aceturato de diminazeno e vitamina E; grupo H, associação de aceturato de diminazeno, selenito de sódio e vitamina E; e por fim o grupo I o qual recebeu uma associação de selenito de sódio e vitamina E. O aceturato de diminazeno foi administrado em dose única no 3º dia pós-infecção (PI). Selenito de sódio e vitamina E foram administradas no 3º e 23º dias PI. Os testes in vivo mostraram aumento da longevidade nos grupos tratados com aceturato de diminazeno associado ao selenito de sódio (grupos F e H). Não foi encontrada diferença entre os grupos C e E, portanto, a vitamina E não aumentou a eficácia do tratamento contra T. evansi quando associado ao aceturato de diminazeno. A eficácia curativa dos tratamentos foi de 37.5, 87.7, 37.7 e 75% para os grupos C, F, G e H, respectivamente. Os demais tratamentos não mostraram eficácia. Assim, podemos sugerir que o selenito de sódio, quando combinado com a quimioterapia pode representar uma alternativa no tratamento da tripanossomose.

Bovine trypanosomosis is a serious constraint to livestock development in large parts of Mozambique. In most areas where tsetse flies are present, the disease in livestock is controlled using curative and prophylactic trypanocidal drugs. Those drugs have been used for many years and new drugs are unlikely to become available in the near future. As a result, trypanosomes have developed resistance against the currently available trypanocidal compounds. Drug resistance has been detected in various African countries and is a serious impediment to the control of livestock trypanosomosis. A study was initiated to determine whether drug resistant trypanosome strains are present in Zambézia Province of Mozambique. The aim of this study was to determine the sensitivity of Trypanosoma congolense isolates from Chinde, Nicoadala and Maganja da Costa Districts to diminazene aceturate, isometamidium chloride and homidium chloride. To assess the effect of the farming system and the intensity of drug regimens on the development of drug resistance, trypanosome isolates were collected from cattle from subsistence, semisubsistence and commercial livestock production systems. Drug-use practices in each of the production systems were determined using a questionnaire. The methodology used to assess the level of drugs resistance in the trypanosome isolates was the standardized method described by Eisler et al. (2001). Seven isolates were selected for resistance testing. For each of the seven isolates, five different doses varying between 0.01-20 mg/kg body weight for isometamidium chloride, 0.01-10 mg/kg body weight for homidium chloride and 1-30 mg/kg body weight for diminazene aceturate were used. For each dose rate six mice were treated intraperitoneally with the appropriate quantity of the drug dissolved in 0.2 ml of sterile distilled water 24 hours after the inoculation of the blood containing the trypanosomes. The control mice (six mice per trypanocidal drug) received the same amount of water without the drug. In four of the seven isolates high levels of multiple drug resistance (diminazene aceturate and isometamidium chloride) were detected. One isolate had a low level of multiple (diminazene aceturate and isometamidium chloride) drug resistance. Two isolates were susceptible to both diminazene aceturate and isometamidium chloride. One of those was highly susceptible to isometamidium chloride even at the lowest dose rate. The observed levels of drug resistance could in most cases be correlated to the drug-use practices in the particular livestock production system. The results obtained from homidium chloride treatment are not conclusive, because most the mice cured after receiving 10 mg/kg body weight of the drug. Hence more research is required to establish the homidium threshold in mice. The results of this study should be useful to define the strategy of disease control in places where resistance of trypanocide were been reported. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2005. / Veterinary Tropical Diseases / unrestricted

Les micelles polyioniques ont émergé comme des systèmes prometteurs de relargage de médicaments hydrophiles ioniques. Le but de cette étude était le développement des micelles polyioniques à base de dextrane pour la relargage de médicaments hydrophiles cationiques utilisant une nouvelle famille de copolymères bloc carboxymethyldextran-poly(éthylène glycol) (CMD-PEG). Quatre copolymères CMD-PEG ont été préparés dont deux copolymères identiques en termes de longueurs des blocs de CMD et de PEG mais différent en termes de densité de charges du bloc CMD; et deux autres copolymères dans lesquels les blocs chargés sont les mêmes mais dont les blocs de PEG sont différents. Les propriétés d’encapsulation des micelles CMD-PEG ont été évaluées avec différentes molécules cationiques: le diminazène (DIM), un médicament cationique modèle, le chlorhydrate de minocycline (MH), un analogue semi-synthétique de la tétracycline avec des propriétés neuro-protectives prometteuses et différents antibiotiques aminoglycosidiques. La cytotoxicité des copolymères CMD-PEG a été évaluée sur différentes lignées cellulaires en utilisant le test MTT et le test du Bleu Alamar. La formation de micelles des copolymères de CMD-PEG a été caractérisée par différentes techniques telles que la spectroscopie RMN 1H, la diffusion de la lumière dynamique (DLS) et la titration calorimétrique isotherme (ITC). Le taux de relargage des médicaments et l’activité pharmacologique des micelles contenant des médicaments ont aussi été évalués. Les copolymères CMD-PEG n'ont induit aucune cytotoxicité dans les hépatocytes humains et dans les cellules microgliales murines (N9) après 24 h incubation pour des concentrations allant jusqu’à 15 mg/mL. Les interactions électrostatiques entre les copolymères de CMD-PEG et les différentes drogues cationiques ont amorcé la formation de micelles polyioniques avec un coeur composé du complexe CMD-médicaments cationiques et une couronne composée de PEG. Les propriétés des micelles DIM/CMDPEG ont été fortement dépendantes du degré de carboxyméthylation du bloc CMD. Les micelles de CMD-PEG de degré de carboxyméthylation du bloc CMD ≥ 60 %, ont incorporé jusqu'à 64 % en poids de DIM et ont résisté à la désintégration induite par les sels et ceci jusqu'à 400 mM NaCl. Par contre, les micelles de CMD-PEG de degré de carboxyméthylation ~ 30% avaient une plus faible teneur en médicament (~ 40 % en poids de DIM) et se désagrégeaient à des concentrations en sel inférieures (∼ 100 mM NaCl). Le copolymère de CMD-PEG qui a montré les propriétés micellaires les plus satisfaisantes a été sélectionné comme système de livraison potentiel de chlorhydrate de minocycline (MH) et d’antibiotiques aminoglycosidiques. Les micelles CMD-PEG encapsulantes de MH ou d’aminoglycosides ont une petite taille (< 200 nm de diamètre), une forte capacité de chargement (≥ 50% en poids de médicaments) et une plus longue période de relargage de médicament. Ces micelles furent stables en solution aqueuse pendant un mois; après lyophilisation et en présence d'albumine sérique bovine. De plus, les micelles ont protégé MH contre sa dégradation en solutions aqueuses. Les micelles encapsulant les drogues ont maintenu les activités pharmacologiques de ces dernières. En outre, les micelles MH réduisent l’inflammation induite par les lipopolysaccharides dans les cellules microgliales murines (N9). Les micelles aminoglycosides ont été quant à elles capable de tuer une culture bactérienne test. Toutefois les micelles aminoglycosides/CMDPEG furent instables dans les conditions physiologiques. Les propriétés des micelles ont été considérablement améliorées par des modifications hydrophobiques de CMD-PEG. Ainsi, les micelles aminoglycosides/dodecyl-CMD-PEG ont montré une taille plus petite et une meilleure stabilité aux conditions physiologiques. Les résultats obtenus dans le cadre de cette étude montrent que CMD-PEG copolymères sont des systèmes prometteurs de relargage de médicaments cationiques. / Polyion complex (PIC) micelles have emerged as promising delivery systems of ionic hydrophilic drugs. It was the aim of this study to develop dextran-based PIC micelles for the delivery of hydrophilic cationic drugs using a new family of carboxymethyldextranblock- poly(ethylene glycol) (CMD-PEG) copolymers. Four CMD-PEG copolymers were prepared: (i) two copolymers identical in terms of the length of CMD and PEG blocks, but different in terms of the charge density of the CMD block; and (ii) two copolymers in which the charged block is the same, but the PEG block is of different molecular weight. The micellization of CMD-PEG copolymers and drug delivery aspects of the resulting micelles were evaluated using different cationic drugs: diminazene (DIM), a model cationic drug, minocycline hydrochloride (MH), a semisynthetic tetracycline antibiotic with promising neuroprotective properties and different aminoglycoside antibiotics. The cytotoxicity of CMD-PEG copolymers was evaluated in different cell lines using MTT and Alamar blue assays. CMD-PEG micelles encapsulating different drugs were characterized using different techniques, such as 1H NMR spectroscopy, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC). The pattern of drug release and pharmacological activity of micelles-encapsulated drugs were also evaluated. The CMD-PEG copolymers did not induce cytotoxicity in human hepatocytes and murine microglia (N9) in concentrations as high as 15 mg/mL after incubation for 24 h. Electrostatic interactions between CMD-PEG copolymers and different cationic drugs triggered the formation of PIC micelles with a CMD/drug core and a PEG corona. The properties of DIM/CMD-PEG micelles were strongly dependent on the degree of carboxymethylation of the CMD block. Micelles of CMD-PEG copolymers having degree of carboxymethylation ≥ 60%, incorporated up to 64 wt% DIM, resisted salt-induced disintegration in solutions up to 400 mM NaCl and sustained DIM release under physiological conditions (pH 7.4, 150 mM NaCl). In contrast, micelles of CMD-PEG of degree of carboxymethylation ~ 30% had lower drug content (~ 40 wt% DIM) and disintegrated at lower salt concentration (∼ 100 mM NaCl). The CMD-PEG copolymer that showed the most satisfactory micellar properties, in terms of high drug loading capacity, sustained drug release and micelles stability was selected as a potential delivery system of minocycline hydrochloride (MH) and different aminoglycosides. CMD-PEG micelles encapsulating either MH or aminoglycosides had small size (< 200 nm in diameter), high drug loading capacity (≥ 50 wt% drug) and sustained drug release. These micelles were stable in aqueous solution for up to one month, after freeze drying and in the presence of bovine serum albumin. Furthermore, the micelles protected MH against degradation in aqueous solutions. Micelles-encapsulated drugs maintained their pharmacological activity where MH micelles reduced lipopolysaccharides-induced inflammation in murine microglia (N9) cells. And aminoglycosides micelles were able to kill a test micro-organism (E. coli X-1 blue strain) in culture. Aminoglycosides/CMD-PEG micelles were unstable under physiological conditions. Micelle properties were greatly enhanced by hydrophobic modification of CMD-PEG. Thus, aminoglycosides/dodecyl-CMD-PEG micelles showed smaller size and better stability under physiological conditions. The results obtained in this study show that CMD-PEG copolymers are promising delivery systems for cationic hydrophilic drugs.

Les micelles polyioniques ont émergé comme des systèmes prometteurs de relargage de médicaments hydrophiles ioniques. Le but de cette étude était le développement des micelles polyioniques à base de dextrane pour la relargage de médicaments hydrophiles cationiques utilisant une nouvelle famille de copolymères bloc carboxymethyldextran-poly(éthylène glycol) (CMD-PEG). Quatre copolymères CMD-PEG ont été préparés dont deux copolymères identiques en termes de longueurs des blocs de CMD et de PEG mais différent en termes de densité de charges du bloc CMD; et deux autres copolymères dans lesquels les blocs chargés sont les mêmes mais dont les blocs de PEG sont différents. Les propriétés d’encapsulation des micelles CMD-PEG ont été évaluées avec différentes molécules cationiques: le diminazène (DIM), un médicament cationique modèle, le chlorhydrate de minocycline (MH), un analogue semi-synthétique de la tétracycline avec des propriétés neuro-protectives prometteuses et différents antibiotiques aminoglycosidiques. La cytotoxicité des copolymères CMD-PEG a été évaluée sur différentes lignées cellulaires en utilisant le test MTT et le test du Bleu Alamar. La formation de micelles des copolymères de CMD-PEG a été caractérisée par différentes techniques telles que la spectroscopie RMN 1H, la diffusion de la lumière dynamique (DLS) et la titration calorimétrique isotherme (ITC). Le taux de relargage des médicaments et l’activité pharmacologique des micelles contenant des médicaments ont aussi été évalués. Les copolymères CMD-PEG n'ont induit aucune cytotoxicité dans les hépatocytes humains et dans les cellules microgliales murines (N9) après 24 h incubation pour des concentrations allant jusqu’à 15 mg/mL. Les interactions électrostatiques entre les copolymères de CMD-PEG et les différentes drogues cationiques ont amorcé la formation de micelles polyioniques avec un coeur composé du complexe CMD-médicaments cationiques et une couronne composée de PEG. Les propriétés des micelles DIM/CMDPEG ont été fortement dépendantes du degré de carboxyméthylation du bloc CMD. Les micelles de CMD-PEG de degré de carboxyméthylation du bloc CMD ≥ 60 %, ont incorporé jusqu'à 64 % en poids de DIM et ont résisté à la désintégration induite par les sels et ceci jusqu'à 400 mM NaCl. Par contre, les micelles de CMD-PEG de degré de carboxyméthylation ~ 30% avaient une plus faible teneur en médicament (~ 40 % en poids de DIM) et se désagrégeaient à des concentrations en sel inférieures (∼ 100 mM NaCl). Le copolymère de CMD-PEG qui a montré les propriétés micellaires les plus satisfaisantes a été sélectionné comme système de livraison potentiel de chlorhydrate de minocycline (MH) et d’antibiotiques aminoglycosidiques. Les micelles CMD-PEG encapsulantes de MH ou d’aminoglycosides ont une petite taille (< 200 nm de diamètre), une forte capacité de chargement (≥ 50% en poids de médicaments) et une plus longue période de relargage de médicament. Ces micelles furent stables en solution aqueuse pendant un mois; après lyophilisation et en présence d'albumine sérique bovine. De plus, les micelles ont protégé MH contre sa dégradation en solutions aqueuses. Les micelles encapsulant les drogues ont maintenu les activités pharmacologiques de ces dernières. En outre, les micelles MH réduisent l’inflammation induite par les lipopolysaccharides dans les cellules microgliales murines (N9). Les micelles aminoglycosides ont été quant à elles capable de tuer une culture bactérienne test. Toutefois les micelles aminoglycosides/CMDPEG furent instables dans les conditions physiologiques. Les propriétés des micelles ont été considérablement améliorées par des modifications hydrophobiques de CMD-PEG. Ainsi, les micelles aminoglycosides/dodecyl-CMD-PEG ont montré une taille plus petite et une meilleure stabilité aux conditions physiologiques. Les résultats obtenus dans le cadre de cette étude montrent que CMD-PEG copolymères sont des systèmes prometteurs de relargage de médicaments cationiques. / Polyion complex (PIC) micelles have emerged as promising delivery systems of ionic hydrophilic drugs. It was the aim of this study to develop dextran-based PIC micelles for the delivery of hydrophilic cationic drugs using a new family of carboxymethyldextranblock- poly(ethylene glycol) (CMD-PEG) copolymers. Four CMD-PEG copolymers were prepared: (i) two copolymers identical in terms of the length of CMD and PEG blocks, but different in terms of the charge density of the CMD block; and (ii) two copolymers in which the charged block is the same, but the PEG block is of different molecular weight. The micellization of CMD-PEG copolymers and drug delivery aspects of the resulting micelles were evaluated using different cationic drugs: diminazene (DIM), a model cationic drug, minocycline hydrochloride (MH), a semisynthetic tetracycline antibiotic with promising neuroprotective properties and different aminoglycoside antibiotics. The cytotoxicity of CMD-PEG copolymers was evaluated in different cell lines using MTT and Alamar blue assays. CMD-PEG micelles encapsulating different drugs were characterized using different techniques, such as 1H NMR spectroscopy, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC). The pattern of drug release and pharmacological activity of micelles-encapsulated drugs were also evaluated. The CMD-PEG copolymers did not induce cytotoxicity in human hepatocytes and murine microglia (N9) in concentrations as high as 15 mg/mL after incubation for 24 h. Electrostatic interactions between CMD-PEG copolymers and different cationic drugs triggered the formation of PIC micelles with a CMD/drug core and a PEG corona. The properties of DIM/CMD-PEG micelles were strongly dependent on the degree of carboxymethylation of the CMD block. Micelles of CMD-PEG copolymers having degree of carboxymethylation ≥ 60%, incorporated up to 64 wt% DIM, resisted salt-induced disintegration in solutions up to 400 mM NaCl and sustained DIM release under physiological conditions (pH 7.4, 150 mM NaCl). In contrast, micelles of CMD-PEG of degree of carboxymethylation ~ 30% had lower drug content (~ 40 wt% DIM) and disintegrated at lower salt concentration (∼ 100 mM NaCl). The CMD-PEG copolymer that showed the most satisfactory micellar properties, in terms of high drug loading capacity, sustained drug release and micelles stability was selected as a potential delivery system of minocycline hydrochloride (MH) and different aminoglycosides. CMD-PEG micelles encapsulating either MH or aminoglycosides had small size (< 200 nm in diameter), high drug loading capacity (≥ 50 wt% drug) and sustained drug release. These micelles were stable in aqueous solution for up to one month, after freeze drying and in the presence of bovine serum albumin. Furthermore, the micelles protected MH against degradation in aqueous solutions. Micelles-encapsulated drugs maintained their pharmacological activity where MH micelles reduced lipopolysaccharides-induced inflammation in murine microglia (N9) cells. And aminoglycosides micelles were able to kill a test micro-organism (E. coli X-1 blue strain) in culture. Aminoglycosides/CMD-PEG micelles were unstable under physiological conditions. Micelle properties were greatly enhanced by hydrophobic modification of CMD-PEG. Thus, aminoglycosides/dodecyl-CMD-PEG micelles showed smaller size and better stability under physiological conditions. The results obtained in this study show that CMD-PEG copolymers are promising delivery systems for cationic hydrophilic drugs.

The aim of this thesis was to provide a picture of the trypanosomosis and drug resistance prevalence in Eastern Province of Zambia, to understand the underlying factors of drug resistance (drug use habits), to improve the diagnosis of trypanosomosis in livestock and finally, to improve the diagnosis of isometamidium resistance in T.congolense. After an introductory part where available trypanosomosis and trypanocide resistance diagnostic methods are described and discussed, the body of the thesis is divided in two main sections. In the first section are presented the results of a cross-sectional and a longitudinal epidemiological survey describing the geographical distribution of trypanosomosis cases, of resistant isolates and of cattle treated with isometamidium chloride. The results of the monitoring of unsupervised treatments of cattle with isometamidium by farmers and veterinary assistants with the Isometamidium-ELISA technique are also presented. The second section describes the development of two new diagnostic methods, the first one allowing the diagnosis of trypanosome infections with high sensitivity and specificity through semi-nested polymerase chain reaction and restriction fragment length polymorphism. This is the first report of a pan-trypanosome PCR test (a single PCR test for the diagnosis of all important pathogenic trypanosomes of cattle). The second new method that was developed allows the diagnosis of isometamidium resistant T.congolense strains by PCR-RFLP. This is the first report of a PCR based diagnostic test of trypanocide resistance in T. congolense.<p> / Doctorat en sciences, Spécialisation biologie moléculaire / info:eu-repo/semantics/nonPublished