Does usnic acid affect microtubules in human cancer cells? / O ácido úsnico pode afetar microtúbulos em células cancerosas humanas?

Usnic acid, a lichen metabolite, is known to exert antimitotic and antiproliferative activities against normal and malignant human cells. Many chemotherapy agents exert their activities by blocking cell cycle progression, inducing cell death through apoptosis. Microtubules, protein structure involved in the segregation of chromosomes during mitosis, serve as chemotherapeutical targets due to their key role in cellular division as well as apoptosis. The aim of this work was to investigate whether usnic acid affects the formation and/or stabilisation of microtubules by visualising microtubules and determining mitotic indices after treatment. The breast cancer cell line MCF7 and the lung cancer cell line H1299 were treated with usnic acid 29 µM for 24 hours and two positive controls: vincristine (which prevents the formation of microtubules) or taxol (which stabilizes microtubules). Treatment of MCF7 and H1299 cells with usnic acid did not result in any morphological changes in microtubules or increase in the mitotic index. These results suggest that the antineoplastic activity of usnic acid is not related to alterations in the formation and/or stabilisation of microtubules.

O ácido úsnico, um metabólito de liquens, é conhecido por sua atividade antimitótica e antiproliferativa em células humanas normais e malignas. Muitos quimioterápicos exercem suas atividades bloqueando a progressão do ciclo celular e induzindo morte celular por apoptose. Os microtúbulos, estruturas protéicas envolvidas na segregação dos cromossomos durante a mitose, servem como alvo quimioterapêutico devido ao seu importante papel tanto na divisão celular quanto nos mecanismos de morte celular por apoptose. O objetivo deste trabalho foi investigar se o ácido úsnico afeta a formação e/ou estabilização dos microtúbulos, a partir da visualização de microtúbulos e determinação de índices mitóticos após o tratamento. Células de câncer de mama MCF7 e de câncer de pulmão H1299 foram tratadas por 24 horas com 29 µM de ácido úsnico e dois controles positivos: vincristina (que impede a formação de microtúbulos) e taxol (que estabiliza microtúbulos). O tratamento das células MCF7 e H1299 com o ácido úsnico não resultou em aumento do índice mitótico. Os resultados sugerem que a atividade antineoplásica do ácido úsnico não está relacionada a alterações na formação e/ou estabilização de microtúbulos.

Relationship between feeding practices and weanling diarrhoea in northeast Thailand.

Diarrhoea is a major public health problem in Thailand. During November 1998-January 1999, a cross-sectional survey and a nested qualitative study were conducted to understand the relationship between feeding practices and weanling diarrhoea, and to describe the related local beliefs and practices in a subdistrict of northeast Thailand. A cluster-sampling method was used for selecting 156 weanlings aged 3-24 months. A structured interview was conducted with the main caregivers of these weanlings. The questionnaire used for the interview included items about feeding practices and diarrhoea-history of the weanlings in 2 months prior to the interview. Seven focus-group discussions with an opportunistic sample of the caregivers were held in the villages. A series of vignettes and unstructured questions were used for eliciting the local beliefs about weanling diarrhoea and its causes. Thirty-six (23%) of the 156 weanlings had diarrhoea in 2 months prior to the interview. The factors that were significantly related to reported weanling diarrhoea included consumption of unboiled water by weanlings (OR = 10, p = 0.03), not covering perishable foods (OR = 3, p = 0.02), and washing feeding utensils of weanlings without dishwashing detergent (OR = 3.1, p = 0.02), 'Su' and 'tongsia'--two common local terms--were used for describing different types of weanling diarrhoea. Many caregivers considered 'su' a natural occurrence in a child's development. The results suggest that some poor feeding practices may contribute to the higher risk of weanling diarrhoea in northeast Thailand. Some local beliefs about weanling diarrhoea may mask the true causes, and mislead messages about its prevention.

Tarifaçäo social no consumo residencial de água / Social tariffs in residential consumption of water

Examina as limitaçöes e os efeitos da adoçäo de uma estrutura tarifária por uma empresa prestadora de serviços de utilidade pública que utiliza um sistema de subsídios cruzados para financiar uma tarifa mais baixa cobrada aos usuários pobres. Exercícios de simulaçäo tarifária säo feitos usando-se tarifas diferenciadas segundo a classificaçäo social dos consumidores, sendo medidos os efeitos que o subsídio provoca em termos da quantidade demandada, das receitas geradas e do seu impacto sobre o nível de bem-estar dos usuários. Mostra como este tipo de estrutura tarifária pode ser convertida naquela na qual as tarifas säo estabelecidas para blocos de quantidades consumidas do serviço. Utiliza estas duas diferentes estruturas tarifárias para mostrar como a estrutura classificatória do usuário é mais eficiente que a outra do ponto de vista de restringir o acesso ao subsídio àqueles que efetivamente necessitam dele.

Schistosomiasis control measures for small irrigation schemes in Zimbabwe : results from three years of monitoring at Mushandike Irrigation Scheme

A pilot study was initiated in 1984 on the 600 ha Mushandike Irrigation Project near Masvingo; Zimbabwe; with the objective of developing and field-testing practical guidelines to reduce the risk of schistosomiasis transmission for use by those involved in planning; designing; constructing and operating small-holder irrigation projects in Zimbabwe. Schistosomisasis is a parasitic disease which is particularly pravalent on irrigation land because of high levels of human contact with water and because colonisation by the aquatic snails; which act as its intermediate hosts; is generally favoured by the equatic enviornments created within irrigation and drainage systems. A number of important phases of the project are complete. These include formulating criteria for schistosomiasis control; implementing these criteria with the design and construction processes; establishing regular monitoring of the human and snail populations and introducing micro-computer assisted irrigation scheduling to reduce the likelihood of smail colonisation in parts of the system. Interim results form the monitoring exercise are now available which enable comparisons to be drawn between different zones of the project and with irrigated land nearby on which control measures have not been introduced. These results indicate that a combination of concrete lining; irrigation scheduling and using innovative control structures on the infield works has had a major impact on the snail hosts. Some disease transmission is; however; occuring in the pilot areas. This is apparently associated with some unsuitable village lacations; inadequate access to safe domestic water supplies and enhanced flows in some natural drainage channels; This report reviews the monitoring to date and discusses what further studies are needed to establish the effectiveness of the control measures