RESUMO
Studies on the role of nutrition in amebiasis in humans and experimental animals are meager. Some reports suggest that malnutrition of the host increases the incidence of infection and potentiates the severity of the disease. Others suggest that malnutrition protects the host against invasion. A few reports indicate that dietary regimens can alleviate symptoms and even eradicate the parasite. Others doubt a correlation between diet and rate of infection or disease manifestations. The problem is complex because the ameba is influenced by its own diet, which in turn depends on the host's diet, the bacterial flora of the gut, and coexisting infections. The host is variously altered by dietary depletions and supplementations, which affect susceptibility and resistance, and by the presence of other disease conditions. Carefully designed and executed studies of infections in humans and experimental animals, combined with studies in vitro of the nutritional requirements and physiology of the parasite, are needed for definition of the influence of host nutrition in amebiasis.
Assuntos
Amebíase/complicações , Distúrbios Nutricionais/complicações , Amebíase/dietoterapia , Amebíase/epidemiologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Criança , Pré-Escolar , Colômbia , Cães , Disenteria Amebiana/complicações , Disenteria Amebiana/epidemiologia , Entamoeba histolytica/patogenicidade , Entamebíase/complicações , Entamebíase/epidemiologia , Eritrócitos/parasitologia , Feminino , Cobaias , Haplorrinos , Humanos , Lactente , Quênia , Abscesso Hepático Amebiano/complicações , Abscesso Hepático Amebiano/epidemiologia , Masculino , Nigéria , Distúrbios Nutricionais/epidemiologia , Ratos , África do Sul , Sri Lanka , Tennessee , TartarugasRESUMO
Eighteen years of technological progress in the field of axenic cultivation of Entamoeba histolytica is reviewed. During this period cumbersome diphasic media gave way to easily prepared clear liquid media. Yields of amebae were increased a thousand fold, and doubling time reduced from 24 to less than 8 hours. Attention is directed to three problems, any one of whose solution will extend the potencial of the axenic cultures. They are 1) to develop a defined medium, 2) to reduce the interval between isolation of the amebae from the host and their establishment in axenic culture, thus lessening the opportunity for selection and/or mutation to occur during a period of high risk, 3) to develop a method whereby the entire life cycle of E. histolytica, and not merely cultivation of the trophic form, can be realized under axenic conditions.
Assuntos
Entamoeba histolytica/crescimento & desenvolvimento , Divisão Celular , Meios de Cultura , Vida Livre de GermesAssuntos
Entamoeba histolytica/metabolismo , Flavoproteínas/metabolismo , Catálise , Transporte de Elétrons , Entamoeba histolytica/análise , Flavinas/metabolismo , Flavoproteínas/antagonistas & inibidores , Humanos , Quelantes de Ferro/farmacologia , NADP/farmacologia , Oxirredução , Compostos de Sulfidrila/farmacologiaRESUMO
The production of cecal lesions with axenically cultivated Entamoeba histolytica in an experimental animal is reported for the first time. Forty-three newborn guinea pigs (one to five days old) were inoculated via laparatomy with 2.5 x 10(5) to 2 x 10(6) strain HM-1-IMSS amebae. Of 23 animals surviving to the 7th postinoculation day all showed cecal lesions at necropsy regardless of the age of the animal when used or the number of amebae received. Ten animals had lesions visible to the unaided eye and 13 had only microscopic lesions. No lesions were noted in other organs of the abdominal or thoracic regiosn. The use of axenically cultivated ameabae in newborn guinea pigs should prove a useful experimental model for the study of amebiasis.
Assuntos
Disenteria Amebiana/parasitologia , Entamoeba histolytica/patogenicidade , Animais , Animais Recém-Nascidos , Ceco/parasitologia , Ceco/patologia , Modelos Animais de Doenças , Disenteria Amebiana/patologia , CobaiasRESUMO
A new technique for growing single Entamoeba trophozoites into colonies in agar has been developed. This method depended upon axenic cultivation and utilized Diamond's new TYI-S-33 medium. The present paper describes several different types of experiment which have utilized the agar technique. a) Cloning. The isolation of clones from agar way easy and successful. Clones of the HM-1 strain did not differ in virulence for newborn hamster liver or in colony morphology or colony forming efficiency. b) Viability measurements. Colony forming efficiency (CFE) was proportional to the number of viable cells in a culture. Pilot studies with the amebacides, metronidazole and emetine, showed that the agar method should be useful in drug testing. Colchicine at high concentration inhibited clonal growth in a non-specific manner. c) E. histolytica HM-1 and E. invadens cells were rapidly killed by exposure to 42 degree C but survived relatively well at 0 degree C. d) Hemolysis. In a preliminary experiment HM-1 colonies did not produce halo's of hemolysis when grown in agar containing sheep red blood cells.