Evidence of prooxidant and antioxidant action of melatonin on human liver cell line HepG2.

The aim of this study was to evaluate melatonin cytotoxicity by measuring its effects on various cellular targets. Cell viability, intracellular reduced glutathione (GSH) level, and reactive oxygen species (ROS) production were assessed in the human liver cell line (HepG2), after incubation with increasing melatonin concentrations (0.1-10,000 microM). The incubation times tested were 24, 72, and 96 h for cell viability and intracellular GSH level, and 15 and 45 minutes for ROS production. Cellular target evaluations were possible in living cells by means of a new microplate cytofluorimeter. This technology was suitable for the assessment of cell viability, GSH level, and ROS overproduction with, respectively, neutral red, monochlorobimane (mBCl), and 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescent probes. At the lowest melatonin concentrations (0.1-10 microM) and for a relatively short incubation time (24 h), the antioxidant effect of melatonin was revealed by an increased intracellular GSH level, associated to cell viability improvement. In contrast, after longer incubation (96 h), cell viability significantly decreased with these lowest melatonin concentrations (0.1-10 microM). Moreover, high melatonin concentrations (1,000-10,000 microM) induced GSH depletion. This oxidative stress is associated with ROS overproduction from 10 microM after only 15 minutes of incubation. This dual effect is strong evidence that, in vitro, melatonin can be both antioxidant and prooxidant on the human liver cell line, depending on the concentration and incubation time.

Tacrine-induced Reactive Oxygen Species in a Human Liver Cell Line: The Role of Anethole Dithiolethione as a Scavenger.

The mechanisms leading to tacrine (THA) hepatotoxic effects are not yet fully understood. Reactive oxygen species (ROS) overproduction and intracellular reduced glutathione (GSH) depletion are common mechanisms involved in drug toxicity. The aim of this study was to investigate, on the human liver cell line HepG2, whether THA at human blood concentrations induces ROS production stimulation and/or GSH depletion. A possible effect of a free radical scavenger, anethole dithiolethione (ADT), was also assessed. ROS production was measured with a fluorogen probe 2',7'-dichlorofluorescin diacetate (DCFH-DA). Reduced GSH and cell viability were measured with, respectively, monochlorobimane (mBCl) and neutral red probes. Assays were performed directly on living adherent cells in 96-well microplates, and sensitive fluorescent detection used microplate cytofluorimetry with cold light fluorimetry technology. The results showed that THA induced a concentration-dependent increase in ROS production and a decrease in GSH. Furthermore, for THA concentrations between 10 and 100 mum, ADT protected cells from ROS production stimulation and GSH depletion induced by THA. In conclusion, our in vitro study demonstrates that oxidative stress, evidenced by enhanced ROS production and GSH depletion, is a mechanism involved in THA cytotoxicity. Moreover, ADT is effective in preventing THA-induced injury.

The Bamako Initiative in Benin and Guinea: improving the effectiveness of primary health care.

The objective of the health system revitalization undergone in Benin and Guinea since 1986 is to improve the effectiveness of primary health care at the periphery. Second in a series of five, this article presents the results of an analysis of data from the health centres involved in the Bamako Initiative in Benin and Guinea since 1988. Data for the expanded programme of immunization, antenatal care and curative care, form the core of the analysis which confirms the improved effectiveness of primary health care at the peripheral level over a period of six years. The last available national data show a DPT3 immunization coverage of 80% in 1996 in Benin and 73% in 1995 in Guinea. In the Bamako Initiative health centres included in our analysis, the average immunization coverage, as measured by the adequate coverage indicator, increased from 19% to 58% in Benin and from less than 5% to 63% in Guinea between 1989 to 1993. Average antenatal care coverage has increased from 5% in Benin and 3% in Guinea to 43% in Benin and 51% Guinea. Utilization of coverage with curative care has increased from less than 0.05 visit per capita per year to 0.34 in Guinea and from 0.09 visit per capita per year to 0.24 in Benin. Further analysis attempts to uncover the reasons which underlie the different levels of effectiveness obtained in individual health centres. Monitoring and microplanning through a problem-solving approach permit a dynamic process of adaptation of strategies leading to a step by step increase of coverage over time. However, the geographical location of centres represents a constraint in that certain districts in both countries face accessibility problems. Outreach activities are shown to play an especially positive role in Guinea, in improving both immunization and antenatal care coverage.

Local cost sharing in Bamako Initiative systems in Benin and Guinea: assuring the financial viability of primary health care.

The fourth in a series of five, this article presents and analyses data on cost recovery and community cost-sharing, two key aspects of the Bamako Initiative which have been implemented in Benin and Guinea since 1986. The data come from approximately 400 health centres and result from the six-monthly monitoring sessions conducted from 1989 to 1993. Community involvement in the financing of local operating costs in the two national scale programmes is also described. In Benin and Guinea, a user fee system generates the community financed revenue with the aim of covering local operating costs including drugs. Health worker salaries remain the responsibility of the government and donor funding covers vaccine and investment costs. Village health committees manage and control resources and revenue. The community is also involved in decision making, strategy definition and quality control. In Benin in 1993, community financing revenue amounted to about US$0.6 per capita per year and generally covered all local recurrent non salary costs except vaccines and left a surplus. Although total costs and revenues were slightly lower in Guinea for the same period, over-all user fee revenue (around US$0.3 per capita per year) covered local recurrent costs (not including salaries or vaccines). A comparison of costs and revenue between regions and individual health centres revealed important differences in cost recovery ratios. In Benin, some centres recovered more than twice the local costs targeted for community financing. Twenty-five per cent of centres in Guinea did not manage to cover their designated local recurrent costs. The longitudinal analysis showed that the level of cost recovery remained stable over time even as preventive care (and especially EPI) coverage rose significantly. To better understand the most important characteristics affecting cost recovery levels, best performing health centres in terms of cost-recovery levels in 1993 were compared to worst performing centres. This analysis showed that the size of the target population of the health centre is a key determinant of cost-recovery in both countries. In addition, in Guinea the utilization of curative care linked to geographical access and in Benin the average revenue per case linked to the number of deliveries proved to be additional factors of importance. In best performing centres, financial viability improved over time in both countries between 1990 and 1993. Finally, the implications of these conclusions for the planning of health centre revitalization in West Africa are discussed.

[Poliomyelitis in Madagascar (1988-1996): current situation in the World Health eradication program by the year 2000]. / La poliomyélite à Madagascar (1988-1996): situation actuelle dans le cadre du programme mondial d'éradication d'ici l'an 2000.

The number of acute flaccid paralysis (AFP) cases reported to World Health Organization (WHO) decreased from 1988 (48 cases) to 1996 (8 cases), but the real endemic situation of poliomyelitis is unknown. Cases are under or misreported. Very often, notifications are delayed; virological investigations of the etiology could not be performed as well as the environment studies and the immunization ripostes. In 1996, only one AFP case was confirmed by isolation of wild poliovirus. The immunization coverage in children under one by OPV (3 doses) was 73.0% in 1996 from the statistics of the Public Health Services but only 54.7% from randomized studies. The eradication of poliomyelitis by the year 2000 has engaged Madagascar in the disease prevention by improving the immunization coverage within the Expanded Immunization Programme in association with the Organization of National Immunization Days in October and November 1997. Likewise, the Virological Unit of the Pasteur Institute was recognized as the National WHO Reference Centre for Polio.

[Integration of the Expanded Program on Immunization into primary health care: examples of Benin and Guinea]. / Intégration du PEV aux soins de santé primaires: l'exemple du Bénin et de la Guinée.

Since 1986, two West African countries have been delivering immunizations within the framework of reorganized peripheral health systems. This revitalization is based on strategies which are implemented by an increasing number of African countries under the name "Bamako Initiative". It aims at providing universal access to a minimum package of maternal and child health priority interventions starting with immunizations, pre and perinatal care, oral rehydration for diarrhoea, treatment of malaria and acute lower respiratory infections. Within this package, immunization has been given high priority. Several strategies aimed at improving immunization coverage have been implemented: services have been reorganized so that any child or woman making contact with the health system receives immunization if needed. Health information systems have been revised so as to allow for active individual follow up and better management of health centre resources. Health staff have been given training in management and a biannual monitoring/microplanning process at health centre level has been introduced. The goal of monitoring is to enable health personnel to identify the obstacles to attaining optimum coverages with the priority interventions and to select locally appropriate corrective strategies. Health centres have also been provided with a motorcycle allowing for regular outreach activities. To cover the running costs of the services (mainly restocking of drugs, running and maintenance of the cold chain and the motorbike, and staff incentives), financial contribution from local communities have been sought through a fee-for-treatment system. Prices have been set at an affordable level by limiting the number of drugs to a minimal list purchased under generic names by international tendering procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

[Missed opportunities in vaccination. A survey in an urban milieu in Cotonou (Benin)]. / Occasions manquées de vaccination. Enquête en milieu urbain à Cotonou (Bénin).

The authors report the results of a survey on missed opportunities for immunization. The exit interview surveys were carried out at seven clinics in Cotonou (Bénin). Missed opportunities show a level from 15% among children and from 21% among attending women. The authors are insisting about the "daily immunization" for the whole country.