Simplification of the polymerase chain reaction for detection of Mycobacterium tuberculosis in the tropics

It has been suggested that the technical complexities, the expense of equipment and consumables, and problems associated with contamination make the polymerase chain reaction (PCR) inappropriate for use in developing countries. These problems were addressed using a novel one-tube nested PCR, small reaction volumes and a 'three room' system for the detection of Mycobacterium tuberculosis. The PCR of sputum samples dried on small filter paper disks was also investigated. Using this strategy 5 smear-positive and 15 smear-negative specimens were correctly identified by PCR. This method of sample collection has the advantage that samples can be sent by post and stored in a minimum of space, and remain viable for PCR for at least 4 years after collection. These and future modifications to the PCR protocol will make the assay more suitable for use in the tropics.

Technological disasters--towards a preventive strategy: a review

Technological or man-made disasters are a growth industry. Widely publicized industrial disasters like those in Bhopal and Chernobyl are only the tip of the iceberg of human and environmental risk from technological development. Other less well publicized disasters, including the contamination of food, water and air, have affected millions of people. The 'slow' technological disasters - like air pollution, pesticides, radiation, lead, asbestos and other industrial hazards - also compromise human intellectual, behavioural and physical development. Although it can be argued that there are hazards attached to virtually every industrial activity and that it is almost impossible to remove completely the risk of technological disasters, it is possible to reduce this risk by decentralizing or deconcentrating knowledge on technological processes. Global recommendations may provide a framework for priority action, but they are obviously not applicable everywhere with the same intensity. A measurement-based approach is described that is beginning to have an effect in several developing countries.

Trypanosoma cruzi infection in the Mexican state of Guerrero: a seroepidemiological (ELISA) survey of 20 communities

The enzyme linked immunosorbent assay (ELISA) was used to analyse 4372 blood samples from residents of 978 households in 20 representative communities in the Mexican state of Guerrero. Seventy-five individuals had very high titres of antibodies against Trypanosoma cruzi. Samples with intermediate optical density values, despite overlapping values with several control positives on a single-well test, did not sustain their positivity at high dilutions. 'Intermediate positives' had a different distribution among the 20 communities to samples sustaining reactivity at high dilutions, indicating possible cross-reactivity with another infectious agent. The finding of seropositive children under the age of 10 years in the Costa Chica, Acapulco and the Tierra Caliente regions, with family clustering of putative cases, indicates that recent transmission must be considered. Very few people interviewed in the 20 communities knew the triatomine bug could transmit a disease.

Pretranslational and posttranslational regulation of the EGF receptor during the prereplicative phase of liver regeneration

We studied the regulation of the epidermal growth factor receptor mRNA and the number of epidermal growth factor binding sites in subcellular compartments involved in the biosynthesis and endocytosis of the epidermal growth factor receptor during the prereplicative phase of liver regeneration. The epidermal growth factor receptor mRNA, quantified by solution hybridization, decreased after partial hepatectomy, with a nadir of about 35% 18 hr after hepatectomy. An even stronger decrease in the number of epidermal growth factor binding sites after partial hepatectomy was observed in a Golgi-enriched low-density membrane fraction, reflecting available newly synthesized epidermal growth factor receptors. It is suggested that this decrease in newly synthesized available epidermal growth factor receptors is caused primarily, but not entirely, by decreased epidermal growth factor receptor mRNA levels and the additional down-regulation of epidermal growth factor binding sites may involve posttranslational mechanisms such as intracellular occupation by transforming growth factor-alpha. The observation that the number of specific epidermal growth factor binding sites after partial hepatectomy was only moderately reduced in prelysosomal endosomes and in lysosomes, compared with the newly synthesized receptors, may indicate that a pool of receptors targeted for lysosomes exists and these receptors are regulated in a different manner than the receptor pool targeted for the cell surface. Furthermore, at least two separable endocytic subcompartments are involved in the transport of the epidermal growth factor/epidermal growth factor receptor complex in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Biosurfactant yields and nutrient consumption of Pseudomonas fluorescens 378 studied in a microcomputer controlled multifermentation system

Production of biosurfactant AP-6 and consumption of carbon (succinic acid) and nitrogen (ammonium ions) by Pseudomonas fluorescens 378 were studied under different growth conditions. The study was performed in a microcomputer controlled multibatch fermentation system which enabled simultaneous running of 10 fermentors. The fermentors were mantled glass vessels, temperature controlled by circulated water, and mixing was arranged by magnetic stirrers. They were connected to the computer system (pH measurement and control) via signal conditioning cards. The microcomputer had a 128 kbytes RAM, two 800-kbyte floppy disc drives, a graphic terminal, and expansion cards. Biosurfactant production was independent of the carbon-to-nitrogen ratio and the phosphorus content in the medium. Omitting the Fe(III) supplement to the medium increased the product yield by 120%. Changes in oxygen transfer rate and pH in the iron deficient cultures did not have any effect on the product yield. Iron deficiency increased the cell consumption of carbon source. Consumption of carbon source in relation to nitrogen uptake (carbon/nitrogen quotient) increased with increasing quotient in the growth medium. The uptake of carbon and nitrogen changed in the intervals of 1.2-1.5 g/g biomass and 0.09-0.16 g/g biomass, respectively. The consumption of carbon increased from 1.5 g/g biomass to 2.0 g/g biomass when the medium concentration of phosphorus was decreased from 0.18 to 0.027 g/L.

Tuberculosis and social stratification in South Africa

Tuberculosis (TB) continues to be a barometer of poverty, determined by racial classification, in both town and countryside in the Republic of South Africa. Despite the fact that whites with the disease stand a greater chance of being diagnosed than their black counterparts, because they have very much better access to health care, the risks of TB for people classified by the state as black and colored are 27 and 16 times, respectively, the risk for whites. Black gold miners, the nutritional elite of the workforce, have also experienced an increase in TB rates. Tuberculosis accounts for 50 percent of all black compensation cases and some 2.5 percent of white cases. The risks of TB have increased over recent years among colored and blacks. Rates of tuberculous meningitis have also increased over the past decade, and show the dramatically worse health care available to people classified as black and colored. Although about 60,000 new TB cases are reported in the country each year, there have been cutbacks in the resources available for TB control and treatment.

[Epidemiologic monitoring and decentralized planification: the use of sentinel sites in Guerrero]

With the current decentralization of health care in the Mexican state of Guerrero, there is need for detailed but inexpensive information for the planning of health services. A cyclical process of measurement is proposed using sentinel sites, characterized as places of concentration of measurement resources, which are not special intervention areas or health facilities. The sites in Guerrero were selected to be representative of the health conditions in the state. During the first two years, study cycles were carried out regarding acute respiratory infections and diarrhoeas in infants, the risk factors associated with these afflictions and the attention paid to them within the community. Later cycles focussed on the importance of scorpion stings and Chagas' disease, the impact of measles vaccination and the prevalence of tuberculosis. Three types of community-based data are considered in each cycle, to optimize their use in planning (impact, coverage and costs) which, in summary formats, facilitate rapid analysis and presentation.

The state, class and the allocation of health resources in southern Africa

In Africa the literature specifically linking the state, class and the allocation of health resources is sparse, and the evidential base for health research is inadequate and difficult to interpret. This paper looks at some of the ways in which state, class and health may be related in southern Africa. The region provides useful comparisons because of the starkness of the relationships between class and race and disease patterns and health care in much of the sub-continent; the different types of state and class structure within southern Africa; and the changes in ideology and to some extent health practice which came with the political independence of some of its component parts. Using both historical and contemporary data, it pinpoints the importance of analysing the specific and changing form of the state in the different countries of the region, in order to understand the social determinants of disease and the allocation of health resources, and looks at the significance of class, race, ethnicity and gender in the incidence of health and the state's response. It highlights the specific colonial legacies, continuing imperial linkages and location of countries in the international division of labour which inhibit changes in health care. Within the region, the migrant labour system and South Africa's aggressive policies of destabilisation create particular problems for weak states and for individuals within them attempting to implement more progressive health care programmes. The paper also argues that the ideological role played by health care has to be understood, and shows the diverse uses to which it is put across the region. The paper concludes that while the position of the state in the international and regional economy, its specific form and the nature of its class relations are predictors in some sense of health and health care, a variety of micro-level political and social decisions and mediations have also to be taken into account. While most of the countries of the region are in some sense part of the 'periphery', and a product of colonialism, these labels are insufficient to explain the differences between them in terms of disease patterns and health care systems. The specificities of internal social dynamics, local class ethnic and gender struggles and political conflicts are also crucial.

Exposure and response to methyl isocyanate: results of a community based survey in Bhopal

In the two weeks immediately after the Bhopal disaster a community based survey was carried out in a series of eight exposed and two non-exposed clusters of households. The primary concern was the effect of the gas (subsequently identified as methyl isocyanate) on the eyes of the victims but data were also sought on respiratory status and the first symptoms of the exposure. No case of blindness was encountered that could be attributed to the gas. The most frequent symptoms reported were burning of the eyes, coughing, watering of the eyes, and vomiting. Among these, the frequency of cough most closely followed the rate of death in the different clusters. Although much rarer overall, the frequency of reported diarrhoea appeared to bear a stronger relation to death rates. Reports of photophobia and the clinical finding of superficial interpalpebral erosion of the cornea were more frequent where the death rates were lower. This clinical and epidemiological picture is consistent with different effects of the gas at different doses (as estimated from distance from the factory).

Apartheid and health in the 1980s

The last 5 years have seen dramatic developments in South Africa, with wide-based internal political struggles and international pressure forcing the government into a well publicized if temporary series of reforms. Yet this has not been paralleled by any substantial improvement in the health conditions of the majority of the population. Apart from improvements in black infant mortality in some urban areas, the health gap remains, a material expression of the social inequality that is part of the definition of apartheid. Black children continue to die from preventible afflictions at about 10 times the rate of their white counterparts. Maternal deaths among women classified as black, coloured or Asian continue to occur, mostly due to septic abortions. At national level, blacks are nearly 30 times more at risk of being diagnosed to have tuberculosis than whites, with some age groups being at still worse risk. Black children under the age of 4 years in Cape Town in 1984 were 205 times more likely to have tuberculosis than their white counterparts. The last 5 years has also seen a revival of rhetoric echoing the international support for primary health care in the 1970s, but health care processes have not been modified to cope with the continuing racial stratification of disease and access to health care. A move towards privatization of the health services has only benefited a few.

Controlled trial of respiratory health worker visiting patients with chronic respiratory disability

Seventy five patients with chronic respiratory disability were randomised to a group visited by a respiratory health worker (42) or control group (33). The first group was visited monthly by a respiratory nurse, who gave education and support. The effect of the intervention was assessed in terms of quality of life (by questionnaires), the number and duration of admissions to hospital, and the number of deaths. The questionnaires on quality of life showed no changes in either group during the study, but nearly all of the group visited by a respiratory health worker said that they valued the visits and wished them to continue. Their knowledge about their condition also improved compared with that of the controls. The duration of stay in hospital for respiratory reasons in the group visited by a respiratory health worker was longer than that of control patients. This was explained by their being scored as more ill than the controls on admission. Fewer patients died in the group visited by a respiratory health worker than in the control group (p = 0.11). The patients in the group visited by respiratory health workers may have survived longer because they sought help rather than dying at home. If confirmed this could have implications for the cost of their care.