Mapping HA-tagged protein at the surface of living cells by atomic force microscopy.

Single-molecule force spectroscopy using atomic force microscopy (AFM) is more and more used to detect and map receptors, enzymes, adhesins, or any other molecules at the surface of living cells. To be specific, this technique requires antibodies or ligands covalently attached to the AFM tip that can specifically interact with the protein of interest. Unfortunately, specific antibodies are usually lacking (low affinity and specificity) or are expensive to produce (monoclonal antibodies). An alternative strategy is to tag the protein of interest with a peptide that can be recognized with high specificity and affinity with commercially available antibodies. In this context, we chose to work with the human influenza hemagglutinin (HA) tag (YPYDVPDYA) and labeled two proteins: covalently linked cell wall protein 12 (Ccw12) involved in cell wall remodeling in the yeast Saccharomyces cerevisiae and the ß2-adrenergic receptor (ß2-AR), a G protein-coupled receptor (GPCR) in higher eukaryotes. We first described the interaction between HA antibodies, immobilized on AFM tips, and HA epitopes, immobilized on epoxy glass slides. Using our system, we then investigated the distribution of Ccw12 proteins over the cell surface of the yeast S. cerevisiae. We were able to find the tagged protein on the surface of mating yeasts, at the tip of the mating projections. Finally, we could unfold multimers of ß2-AR from the membrane of living transfected chinese hamster ovary cells. This result is in agreement with GPCR oligomerization in living cell membranes and opens the door to the study of the influence of GPCR ligands on the oligomerization process.

Nanoscale structural mapping as a measure of maturation in the murine frontal cortex.

Atomic force microscopy (AFM) is emerging as an innovative tool to phenotype the brain. This study demonstrates the utility of AFM to determine nanomechanical and nanostructural features of the murine dorsolateral frontal cortex from weaning to adulthood. We found an increase in tissue stiffness of the primary somatosensory cortex with age, along with an increased cortical mechanical heterogeneity. To characterize the features potentially responsible for this heterogeneity, we applied AFM scan mode to directly image the topography of thin sections of the primary somatosensory cortical layers II/III, IV and V/VI. Topographical mapping of the cortical layers at successive ages showed progressive smoothing of the surface. Topographical images were also compared with histochemically derived morphological information, which demonstrated the deposition of perineuronal nets, important extracellular components and markers of maturity. Our work demonstrates that high-resolution AFM images can be used to determine the nanostructural properties of cortical maturation, well beyond embryonic and postnatal development. Furthermore, it may offer a new method for brain phenotyping and screening to uncover topographical changes in early stages of neurodegenerative diseases.

Standard-risk medulloblastoma treated by adjuvant chemotherapy followed by reduced-dose craniospinal radiation therapy: a French Society of Pediatric Oncology Study.

OBJECTIVE: The primary objective of this study was to decrease the late effects of prophylactic radiation without reducing survival in standard-risk childhood medulloblastoma. PATIENTS AND METHODS: Inclusion criteria were as follows: children between the ages of 3 and 18 years with total or subtotal tumor resection, no metastasis, and negative postoperative lumbar puncture CSF cytology. Two courses of eight drugs in 1 day followed by two courses of etoposide plus carboplatin (500 and 800 mg/m(2) per course, respectively) were administered after surgery. Radiation therapy had to begin 90 days after surgery. Delivered doses were 55 Gy to the posterior fossa and 25 Gy to the brain and spinal canal. RESULTS: Between November 1991 and June 1998, 136 patients (median age, 8 years; median follow-up, 6.5 years) were included. The overall survival rate and 5-year recurrence-free survival rate were 73.8% +/- 7.6% and 64.8% +/- 8.1%, respectively. Radiologic review showed that 4% of patients were wrongly included. Review of radiotherapy technical files demonstrated a correlation between the presence of a major protocol deviation and treatment failure. The 5-year recurrence-free survival rate of patients included in this study with all optimal quality controls of histology, radiology, and radiotherapy was 71.8% +/- 10.5%. In terms of sequelae, 31% of patients required growth hormone replacement therapy and 25% required special schooling. CONCLUSION: Reduced-dose craniospinal radiation therapy can be proposed in standard-risk medulloblastoma provided staging and radiation therapy are performed under optimal conditions.

Treatment of high risk medulloblastomas in children above the age of 3 years: a SFOP study.

AIM: Improvement of EFS of children older than 3 years with high risk medulloblastoma. METHODS: Between 1993 and 1999, 115 patients (3-18 years, mean 8 years) with high risk medulloblastoma were included. After surgery treatment consisted of chemotherapy ('8in1' and etoposide/carboplatin) before and after craniospinal radiotherapy. RESULTS: Patients were staged using Chang-criteria (PF residue only, M1 and M2/M3) by local investigator as well as by central review panel (82.4% concordance). Chemotherapy was well tolerated without major delays in radiotherapy. With a mean follow up of 81 months (9-119), 5-year EFS was 49.8% and OS 60.1%. In detail according to subgroups EFS was 68.8% for PF residue only, 58.8% for M1 disease and 43.1% for M2/M3. CONCLUSION: M1 patients are legitimate high risk patients. Survival rates are still very low for high risk medulloblastoma patients and future trials should therefore focus on more intensive (chemotherapy/radiotherapy) treatment.

Analysis of Arrestin Recruitment to Chemokine Receptors by Bioluminescence Resonance Energy Transfer.

Chemokine receptors recruit the multifunctional scaffolding protein beta arrestin in response to binding of their chemokine ligands. Given that arrestin recruitment represents a signaling axis that is in part independent from G-protein signaling, it has become a hallmark of G protein-coupled receptor functional selectivity. Therefore, quantification of arrestin recruitment has become a requirement for the delineation of chemokine and drug candidate activity along different signaling axes. Bioluminescence resonance energy transfer (BRET) techniques provide methodology for such quantification that can reveal differences between nonredundant chemokines binding the same receptor, and that can be upscaled for high-throughput testing. We here provide protocols for the careful setup of BRET-based arrestin recruitment assays, and examples for the application of such systems in dose-response or time-course experiments. Suggestions are given for troubleshooting, optimizing test systems, and the interpretation of results obtained with BRET-based assays, which indeed yield an intricate blend of quantitative and qualitative information.

The protective effects of zinc in experimental gentamicin induced acute renal failure in rats.

This study investigates the effects of zinc in acute kidney injury induced by gentamicin (Ge). We used Wistar male rats distributed in 4 groups of 12 animals each, treated intraperitoneally as follows: Group I (Control) treated with distilled water; Group II (Ge) with experimental induced acute renal failure with Ge; Group III (Ge + Zn) administration of ZnCl2 in animals with experimental induced renal failure with Ge, Group IV (Zn) treated with ZnCl2 as positive control. We measured serum levels of urea, creatinine, total antioxidant status, superoxide dismutase, glutathione peroxidase and urinary proteins before the nephrotoxicity induction (baseline) and 3, 7 and 10 days after Ge administration. The renal histopathological analysis was also done. The results showed an increase of urea and creatinine values in Ge + Zn group after 7 days compared to baseline, but less accentuated than those in Ge group. Zn supplementation was associated with an increase of the total antioxidant status in Ge + Zn group compared to Ge group (P < 0.01). It was also revealed a significant reduction of proteinuria in Ge + Zn group compared to Ge group (P < 0.001). The histopathological investigation highlighted the tubular necrosis affecting more than 90% of proximal tubules in Ge group. In Ge + Zn group it was observed a milder degree of tubular necrosis (influencing less than 25% of proximal tubules), a moderate inflammation and the presence of tubular regeneration. In conclusion, Zn administration proved a to have a protective role in experimental gentamicin-induced acute renal failure.

Costs and outcomes of liver transplantation in adults: a prospective, 1-year, follow-up study. GRETHECO study group.

BACKGROUND: Orthotopic liver transplantation (OLT) is widely used to treat patients with end-stage liver disease. However, data on the cost of the procedure are fragmentary. We evaluated the costs, as calculated from resource use, and outcomes of OLT in adults, from registration on the transplant waiting list to the end of the 1st-year of follow-up after the transplant. METHODS: Two parallel cohort studies were conducted from 1994 to 95. All patients ages 18 years and older, on the waiting list (n=33) according to national criteria or having undergone transplants (n=38) were followed for 1 year or until either the transplant (waiting list cohort) or death (waiting list and transplantation cohorts). RESULTS: Eighty percent of the patients undergoing transplants were alive after 1 year, and no patient died while on the waiting list. However, the estimated cost of the procedure was high: more than 55,000 pound silver for the 1st year after OLT, to be added to 5,500 pound silver for evaluation and further costs motivated by the planned transplant during an average 6.5 months on the waiting list. Age over 40 and a baseline Child-Pugh score of 10 and over were predictive of high costs. The proportion of costs associated with immunosuppressive therapy and rejection were very high. CONCLUSIONS: This medical and economic cohort study suggests that OLT is still expensive; the study identifies sources of extra cost that could be limited either by improved selection of patients or, in the future, by technological advances in immunosuppressive therapy that help avoid medical complications. It also suggests the situation is precarious, with outcomes and costs being very sensitive to variation in graft availability.

Homologous regulation of the alpha2C-adrenoceptor subtype in human hepatocarcinoma, HepG2.

1. Previous studies of the regulation of the alpha2C-adrenoceptor in OK and in transfected cells have led to discrepant conclusions. In the present work, we examined the homologous regulation of the human alpha2C-adrenoceptor in the hepatocarcinoma cell-line, HepG2; a model which expresses this subtype spontaneously. 2. Short-period treatment of the cells with UK14304 provoked neither a diminution of the potency of the alpha2-agonist to inhibit forskolin-induced cyclic AMP-accumulation nor a change in the degree of receptor coupling to G-proteins. 3. Long-period exposure to UK14304 resulted in a large reduction of [3H]MK912 binding sites (55% decrease). The action of UK14304 was dose-dependent (EC50 = 190 +/- 45 nM), rapid (t1/2 = 4.2 h) and reversible. Receptor down-regulation was also observed with clonidine or (-)adrenaline (38 and 36% decrease, respectively) and was blocked by the addition of alpha2-antagonists. 4. Conversely to that observed with alpha2-agonists, treatment of the cells with RX821002 or yohimbine alone, but not with phentolamine, promoted a significant increase of the receptor expression. 5. The observed alterations of receptor density are not the reflection of changes at the alpha2C4 mRNA level. Estimation of the receptor protein turnover and measurement of its half-life demonstrated that down-regulation by alpha2-agonists and up-regulation by alpha2-antagonists, with inverse-agonist efficacy, are respectively the consequence of increased and decreased rate of receptor degradation. 6. In conclusion, our data show that alpha2C-adrenoceptor does not undergo desensitization but is down-regulated in HepG2. The lack of desensitization agrees with previous results obtained in cells transfected with the alpha2C4 gene, but not with observations made in OK cells. Inversely, down-regulation fits with results obtained in OK but not in transfected cells. The reasons for these discrepancies are discussed. Our results also demonstrated that certain alpha2-antagonists behave as inverse agonist on the HepG2 model and thus provide for the first time evidence of inverse efficacy of antagonists on a cellular model expressing physiological level of a wild-type alpha2-adrenoceptor.

Contrasted diffusion and the use of CT scanner equipment in France.

During the last 4 years, there has been a rapid catching-up in the distribution level of CT-scanners in France. In a survey of CT-scanner utilization, data from all machines operating in the PACA Region in 1986, showed that the mean activity was 6,080 examinations per machine. The co-existence of both private and public medicine led to different use of materiel (5,500 to 5,800 exams per machine in the public versus 8,600 in the private sector and a higher productivity in the profit-making establishments. This difference was not explained by procedural variations in carrying out the technique, which appeared to be similar and standardized everywhere, but probably reflected patient selection (80% of ambulatory patients in the private sector, 25 to 50% in PTH).

Cost-effectiveness of HIV screening of pregnant women in hospitals of the Paris area. The Paris-Tours study group of antenatal transmission of HIV, Group '9 maternites'.

In the context of an epidemiologic multicentric study about perinatal transmission of HIV, screening was systematically proposed to all pregnant women attending nine maternities clinics of the Paris region (n = 7600, between August 1987 and July 1988) at their first prenatal visit. Among them, 2145 had already been tested and 45 were known to be HIV positive. So, 5660 tests were performed during the first 6 months (period 1), and 17 pregnant women were discovered to be positive. The total cost of screening has been estimated between FF. 720,000 and 775,000, resulting in a mean cost per pregnant woman found to be HIV positive of about FF. 42,000 to 45,000. A similar calculation over the following 5 months (period 2) gave a mean cost of between FF. 165,000 and 178,000. Since the women, before being screened, had to answer a short questionnaire about risk factors; cost and effectiveness of a selective screening strategy could be simulated. The preference of systematic screening to selective screening enabled the discovery of two HIV positive cases in each period, the marginal cost, i.e., cost per extra pregnant woman found to be HIV positive was thus FF. 303,320 to 327,540 for period 1, and FF. 572,240 to 619,000 for period 2. Although these figures seem high, an estimation of the cost-effectiveness does not allow us to conclude whether it is in society's interest to devote the funds necessary to move away from selective screening towards systematic screening.(ABSTRACT TRUNCATED AT 250 WORDS)

Social perception of AIDS in the general public: a French study.

The paper presents the results of the first national survey about social perception of AIDS in a representative sample of the French general public (which was carried out in June 1987). A large majority of the French public (73.1% of respondents) support mandatory screening for HIV, and a significant part (21.9% of respondents) even favours isolation of AIDS patients. Results show the relations between false beliefs on transmission of AIDS by casual contact and willingness to agree with measures that carry a great danger of stigmatization for AIDS patients and HIV carriers; but strong correlations between support of coercive measures for prevention of AIDS and similar opinions on other controversial issues suggest that, for a fraction of the public, attitudes about AIDS are rather determined by a priori ideological and ethical values than by risk perception of the disease per se. Results also suggest that any ambiguity in scientific information about AIDS may increase social pressure, even among the most educated part of the population, for unnecessary measures. Tentative conclusions for public policy on prevention and information about AIDS are drawn.

Cost-effectiveness of monolayers and human papillomavirus testing compared to that of conventional Papanicolaou smears for cervical cancer screening: protocol of the study of the French Society of Clinical Cytology.

The French Society of Clinical Cytology is conducting a study to compare the cost-effectiveness of monolayers and human papillomavirus (HPV) testing with that of conventional Papanicolaou (Pap) smears for cervical cancer screening. The protocol of this study is presented. It includes 3,000 women who will be evaluated by the three methods (conventional Pap smears, or monolayers with or without HPV testing) and by the reference method: colposcopy followed, in cases with abnormalities, by cervical biopsy. Efficacy or performance of the methods will be compared on the basis of sensitivity. Cost comparisons and cost-effectiveness modeling will be based on the costs associated with methods themselves and also the costs of "false positives." This will require specific collection of data concerning the costs of the three methods, as these costs have not previously been accurately documented. Patient recruiting and data collection started in September 1999 and will be complete in June 2000. The first results are expected to be available in spring 2001.

[Cost-effectiveness analysis of the treatment of chronic hepatitis C]. / Analyse coût-efficacité du traitement de l'hépatite chronique C.

OBJECTIVES: Chronic active hepatitis C is an important public health issue because of its prevalence, evolution, and overall cost. Treatment by recombinant alpha-interferon is both expensive and exacting and its effectiveness is limited. We report the results of a cost-effectiveness analysis of alpha-interferon treatment in patients with chronic active hepatitis C. METHODS: Direct medical costs of caring for patients with chronic active hepatitis C and its complications, based on treatment or no treatment, were assessed with retrospective data collected from the files of 137 hospital patients. Seventy-seven patients were treated with alpha-interferon between 1988 and 1994. The overall costs of caring for chronic active hepatitis C patients, without treatment or with alpha-interferon treatment (3 millions units three times a week) for 6 months (strategy A), 12 months (strategy B), or 12 months but discontinuing treatment when there was no response (strategy C), was reported and compared to the respective effectiveness of each. RESULTS: With an actualization rate of 5%, the real overall cost of caring for a chronic active hepatitis C patient was 143290 FF. Considering the contraindication rate (15%), the treatment acceptance (85%), the response rate to treatment (50%), and the prolonged response rate (25 to 30%), treating patients with strategy A induced a real overall cost of caring to 140731 FF to avoid 0.11 cases of cirrhosis, to 150277 FF to avoid 0.13 cases of cirrhosis with strategy B, and to 136947 FF to avoid 0.13 cases of cirrhosis with strategy C. CONCLUSION: Alpha-interferon treatment in patients with chronic active hepatitis C provides a long-term saving compared to cases which receive no treatment. Strategy C was the most cost-effective, inducing the reduction of both the number of cases of cirrhosis and the cost of care.

[Model for evaluation of occupational mortality related to asbestos (the case of the asbestos industry in France between 1950 and 1980)]. / Un modèle d'évaluation de la mortalité professionnelle liée à l'amiante (Le cas de l'industrie de l'amiante en France entre 1950 et 1980).

This article presents an evaluation model of the mortality attributed to asbestos occupational exposure. French workers exposed at least ten years between 1950 and 1979 constitute the population studied. Exposure-risk relations are used to estimate mortality from lung cancer, mesothelioma, or asbestosis, and the associated reduction of life expectancy among 76 groups (about 18,500 workers) defined by their level of asbestos exposure. The most important results are presented and discussed as are the main hypotheses regarding historical exposure parameters.

[Methodologic contribution to determining maximum occupational exposure levels for asbestos. Exposure-risk relation and economic criteria]. / Contribution méthodologique à la détermination de valeurs limites d'exposition professionnelle à l'amiante. Relation exposition-risque et critères économiques.

It is not easy to set exposure limits for industrial carcinogens when only biological and epidemiological criteria are used. Hence, criteria should also include relevant social and economical considerations. This paper, using asbestos exposure as an example, explains how the economic aspects of prevention may be taken into account. The methodology includes three stages: use of the exposure-risk models in order to estimate the residual health effects associated with asbestos, according to various exposure limits, evaluation of costs of preventive measures required by these exposure limits, discussion of the exposure limits--a synthesis of the two preceding stages.

[Economic evaluation of interventions in public health: potentials and limitations]. / L'évaluation économique des interventions en santé publique: principes et limites.

One of the main principles of economic evaluation refers to the scarcity of resources. So, choices must and will be made concerning the commitment of these resources to one use instead another. Economic evaluation can assume different methodological forms regarding the kind and complexity of programme to be assessed and the issue of outcome valuation, but each analytic technique compares the resources consumed by different relevant alternatives with the health improvements and other consequences arising from them. From a pragmatic point of view, four types of economic evaluation can be distinguished associated with different measurement and valuation of consequences: cost-minimization, cost-effectiveness, cost-utility and cost-benefit analysis. A first step of economic appraisal is definition and description of each competing alternative. Then, there are difficulties associated with measurement and valuation of both costs and effectiveness of alternatives. The assessment of public health interventions poses some special problems in terms of time profiles of cost and consequences. Most of the costs of a health programme incurred in the present while benefits will come later in the future. Therefore, cost and consequences must be discounted to reflect the existence of time preference. The last important point concerns the assessment of health consequences. Ideally, evaluation of efficacy takes the form of a well controlled randomized trial designed for this purpose. But, in many situations, this approach is not relevant, appropriate or feasible and efficacy appraisal must be developed on the basis of available data and "realistic" assumptions. So, every evaluation will contain some degree of uncertainty or imprecision and a sensibility analysis must be performed in order to test sensitivity of the results to alternative assumptions and uncertainty.

[Economic analysis of neonatal screening for drepanocytosis in metropolitan France]. / Analyse économique du dépistage néonatal de la drépanocytose en France métropolitaine.

There is indisputable evidence that mortality and morbidity can be significantly reduced by programmes that screen newborns for sickle cell disease. But in the French epidemiological context, national decision regarding generalization of local screening programmes to all newborns must take into account economic considerations as at-risk populations represent, in most geographic areas, a few percent of the total population. Targeted screening can be considered but raises ethical and practical issues. In order to compare alternative screening strategies, a cost-effectiveness analysis has been performed. The analysis is based on a screening programme of newborns conducted in the south-eastern suburb of Paris. Strategies have been defined in terms of laboratory procedures (isoelectrofocalisation, electrophoresis on citrate agar, high pressure liquid chromatography, BIORAD technique,...) and methods for blood collection (dried paper, micro-tube). An evaluation of all the necessary costs have been performed for each strategy in the biochemistry laboratory in charge of the neonatal programme. Costs have been estimated from detailed observation of physical quantities of capital and labour involved in each case. Evolution of unit and marginal costs according to the level of annual production has been assessed. Effectiveness has been measured in terms of number of sickle cell cases detected. Screening of at-risk babies in Paris region would permit detection of 80 to 215 babies each year at a unit cost per case found varying from 1 to 2,800 US$ (according to hypothesis of prevalence). When compared with other programmes of prevention, results of selected screening of newborns in whole metropolitan France suggest that this action might be discussed by public health authorities.

[Prevention of occupational carcinogens: perspectives opened by the evaluation of risks and preventive actions]. / La prévention des cancérogènes professionnels: les perspectives ouvertes par l'évaluation des risques et des actions de prévention.

The first part of the review deals with the present situation in terms of prevention against potential carcinogenic substances in France. A significant effort should be devoted to the measurement of contaminants--not only carcinogenic substances--in the workplace. This is a prerequisite for setting a data base in terms of potential occupational risk. Moreover gaps exist also as far as the definition of the technical means aimed at the reduction of risk is concerned. These conclusions put into light the importance of the contribution that "industrial hygienists" would bring in France. In the second part of the review, the methodological content of the risk assessment and risk management procedures is described and illustrated. Risk assessment of carcinogens deals: with the identification of potential carcinogens through epidemiology, animal bio-assays and short term tests; with the quantitative estimation of the magnitude of the potential carcinogenic risk among the exposed workers. It appears necessary to carry out systematic surveys of the number of workers exposed to the carcinogenic substances. The risk assessment procedure is applied to 5 substances BCME, MOCA, Acrylonitrile, Chromium, Nickel and some compounds of these metals. The number of potential excess cancers related to a unit lifelong exposure to Nickel compounds is estimated. This requires exposure-response models which are critically analysed. Risk management is devoted to the choice of primary health care policies. The methodology of risk management consists of: identifying various control policies; quantitative estimation of their efficiency--indicators of the efficiency are discussed--and of their cost; choice among these policies with the help of a cost-effectiveness analysis when necessary. The procedure is illustrated in the case of Acrylonitrile control in a facility.

[Evaluation of the policies for detection of pulmonary tuberculosis in France]. / Contribution à l'évaluation de la politique de dépistage de la tuberculose pulmonaire en France.

A survey of 984 cases of pulmonary tuberculosis was carried out to assist French public health authorities in determining policies for pulmonary tuberculosis detection. The adjusted sample was representative of the totality of pulmonary tuberculosis cases reported. The survey made it possible to define the economic and socio-demographic characteristics (age, nationality, lack of social security coverage, living conditions) which, when combined, represent high-risk attributes with regard to pulmonary tuberculosis. Nonetheless, over half the subjects studied presented no risk factors. Systematic X-ray screening of an undifferentiated population permits detection of about 23% of reported cases; among them, 26 or 50% (depending on the definition of contagiousness chosen) were contagious. In 1982, 9 million systematic X-ray screenings were performed and about 13,100 cases of pulmonary tuberculosis reported. When extrapolated to these 1982 figures, our survey conclusions point to an effectiveness rate for systematic X-ray screening of 33.7 per 100,000 for the overall tuberculosis population, and between 8.9 and 17.4 per 100,000 for contagious cases. On the other hand, high-risk groups (female immigrants, the aged, etc.) do not seem to be particularly well covered by systematic X-ray screening. Thus, maintaining such a program no longer appears justified either in terms of the overall tuberculosis population or that of high-risk subgroups.

[Evaluation of the cost-effectiveness of school screening for hereditary hemoglobin abnormalities: prospective study in Bouches-du-Rhône. School screening for hemoglobinopathies]. / Evaluation coût-efficacité du dépistage scolaire des anomalies héréditaires de l'hémoglobine: une étude prospective dans les Bouches-du-Rhône. Dépistage scolaire des hémoglobinoses.

Screening in schools for heterozygote carriers of haemoglobinopathies traits has been carried out experimentally in southeast France ("Bouches du Rhône", the Marseille region) since 1977. The study compares, in cost-effectiveness terms, the screening strategy now followed with 27 alternative strategies in all the pupils (14-16 years). Although the frequency of heterozygote carriers in this school population as a whole is only 7.9% carriers for beta-thalassaemia gene and 2.5% carriers for HbS, prospective costs per diagnosis still seem reasonable: from 1544 to 4997 French francs (1987) depending on the strategy, and 2099 to 7380 francs if beta-thalassaemia alone is screened. In comparison with the current screening strategy, cost-effectiveness ratios could be improved by using haemoglobin electrophoresis as a preselection test, or a blood count if beta-thalassaemia alone is screened. Further improvement of cost-effectiveness ratios could be obtained by limiting screening to ethnic groups most "at risk"; but such strategies raise ethical and acceptability issues.