Working Paper 51 - Competition and Regulation in Infrastructure

La réforme réglementaire de l'infrastructure africaine s'est accélérée depuis 1995, pas nécessairement à cause de la gestion publique éclairée de la part des gouvernements africains, bien qu'une telle interprétation puisse être soutenue dans certains milieux, mais surtout à cause de l'écart non justifié du revenu par habitant par rapport à celui des autres régions en développement qui ne peut plus être ignoré par les institutions multilatérales et autres bailleurs de fonds, et de la nécessité de développer les marchés pour les produits des pays industrialisés. Ce n'est donc pas par hasard que la région accorde maintenant plus -tutelle ne l'a fait par le passé, une attention particulière à l'annulation de la dette, au renforcement des capacités, et autres projets de développement humain. Même le FMI a annoncé l'adoption d'une nouvelle approche à ses prescriptions de restructuration économique qui, jusqu'à ce jour, sont restées constantes. Par ailleurs, les progrès technologiques ont permis aux pays développés d'adopter une nouvelle approche à la canalisation des ressources vers l'Afrique à un rythme différent de celui que l'on a connu par le passé.En dépit de la relance de l'activité économique sur le continent, les IFD opérant dans la région sont encore à un stade expérimental et sont fortement concentrées dans quelques pays seulement. II est clair que, tels que perçus par les investisseurs privés, les avantages potentiels de l'investissement dans les pays africains sont encore insignifiants par rapport aux risques. En effet, à l'exception de quelques projets de construction-exploitation-transfert dans les secteurs de l'électricité et de l'eau, l'investissement et, par conséquent, la concurrence, porte essentiellement sur les segments contestables des marchés dans quelques pays. Ainsi, du point de vue de l'investisseur privé, la réforme réglementaire dans la fourniture des services d'infrastructure dans la région a encore beaucoup de chemin à faire, et ce qui a été fait à ce jour, reste encore à prouver. D'autre part, les gouvernements de la plupart des pays africains sont aussi prudents en ce qui concerne l'ouverture du secteur à la participation privée, de peur d'être envahis par les investisseurs étrangers en quête de rendements à court terme. En conséquence, le processus de réforme a été largement fondé sur la suppression des monopoles dans le secteur des télécommunications et l'octroi de concessions dans d'autres; la participation des employés et collectivités locales constituant de ce fait un facteur important du processus.Mais, malgré les positions conflictuelles apparentes de l'investisseur privé et du gouvernement, la baisse de la barrière intrinsèque à la participation privée est inévitable, en termes équitables. Les nouvelles techniques réglementaires conçues pour s'adapter aux progrès technologiques du secteur servent aussi à offrir aux deux parties la possibilité d'adopter une approche gradualiste au processus de réforme. Et avec l'expansion, également inévitable, de la zone de confort, il est fort possible que le gouvernement et l'investisseur privé arrivent à cohabiter dans un cadre de coopération et de respect mutuels, dans l'intérêt de tous les participants.

In-vitro toxoplasmacidal activity of cationic electron carriers

Exposing murine macrophages infected th the protozoan parasite Toxoplasma gondii to micromolar concentrations of some cationic electron carriers (dyes), resulted in complete killing of the intracellular parasites at concentrations at which these compounds did not seem toxic for the macrophages. The 50% inhibitory concentrations (with 95% confidence limits) were calculated as 0·26 (0·18-0·37), 1·35 (1-2·25), 0·45 (0·13-1·50), and 1·52 (0·91-2·53) μM for crystal violet, phenazine methosulphate, methylene blue and brilliant cresyl blue, respectively. The effects of these electron carriers did not appear to be the result of an enhancement of the natural antitoxoplasmic activity of the macrophages. None of the tested compounds was active against extracellular Tox. gondii as measured by ability to reinfect murine macrophages; thus, these dyes seem to act primarily on actively metabolizing, intracellular, Tox. gondii. Our data also suggest that the killing effect of the electron carriers was not related to the generation of reactive oxygen intermediates as judged by the inability of scavengers of these intermediates to block the activity against intracellular Tox. gondii. Further studies with related redox compounds would have an interesting chemotherapeutic perspective for treating toxoplasma infection

Activity of roxithromycin against Toxoplasma gondii in murine models

Investigations into the activity of roxithromycin against murine toxoplasma infections are reviewed. Roxithromycin is an active drug against murine toxoplasmosis after intraperitoneal challenge with the RH strain of Toxoplasma gondii. Roxithromycin protected 100% of mice after five daily doses of 540 mg per kg administered by gavage. The cure rate after treatment of peritoneal infections seemed to be related to the length of the therapy. Roxithromycin also decreased the number of toxoplasma cysts, after intracerebral infection with the C56 strain and showed synergistic activity when combined with gamma interferon. Thus, roxithromycin could be a worthwhile alternative to current therapy against toxoplasma infections. Clinical studies on its activity and safety, especially in pregnancy, are warrante

Activity of spiramycin against Toxoplasma gondii in vitro, in experimental infections and in human infection

The in-vitro, experimental and clinical activities of spiramycin against Toxoplasma gondii have been reviewed. In mammalian cells infected by T. gondii as in various experimental models, spiramycin definitively exerts an inhibitory antitoxoplasmic effect which, clinically, seems useful for preventing congenital toxoplasma infection during pregnancy or for reducing the inflammation in toxoplasmic chorioretinitis. However, spiramycin does not kill the parasite efficiently, and cannot be recommended for eradicating the most severe forms of toxoplasmosi

Analysis of Pregnancy and Other Factors on Detection of Human Papilloma Virus (HPV) Infection Using Weighted Estimating Equations for Follow-Up Data

Generalised estimating equations have been well established to draw inference for the marginal mean from follow-up data. Many studies suffer from missing data that may result in biased parameter estimates if the data are not missing completely at random. Robins and coworkers proposed to use weighted estimating equations (WEE) in estimating the mean structure if drop-out occurs missing at random. We illustrate the differences between the WEE and the commonly applied available case analysis in a simulation study. We apply the WEE and re-analyse data on pregnancy and HPV infection. We estimate the response probabilities and demonstrate that the data are not missing completely at random. Upon use of the WEE, we are able to show that pregnant women have an increased odds for an HPV infection compared with study subjects after delivery (p = 0.027). We conclude that the WEE are useful in analysing follow-up data with drop-outs

Carcinogen metabolism, cigarette smoking, and breast cancer risk: a Bayes model averaging approach

BACKGROUND: Standard logistic regression with or without stepwise selection has the disadvantage of not incorporating model uncertainty and the dependency of estimates on the underlying model into the final inference. We explore the use of a Bayes Model Averaging approach as an alternative to analyze the influence of genetic variants, environmental effects and their interactions on disease. METHODS: Logistic regression with and without stepwise selection and Bayes Model Averaging were applied to a population-based case-control study exploring the association of genetic variants in tobacco smoke-related carcinogen pathways with breast cancer. RESULTS: Both regression and Bayes Model Averaging highlighted a significant effect of NAT1*10 on breast cancer, while regression analysis also suggested a significant effect for packyears and for the interaction of packyears and NAT2. CONCLUSIONS: Bayes Model Averaging allows incorporation of model uncertainty, helps reduce dimensionality and avoids the problem of multiple comparisons. It can be used to incorporate biological information, such as pathway data, into the analysis. As with all Bayesian analysis methods, careful consideration must be given to prior specification

Effects of ampicillin, ceftriaxone, chloramphenicol, pefloxacin and trimethoprim-sulphamethoxazole on Salmonella typhi within human monocyte-derived macrophages

The killing effect of various antimicrobial agents used in the therapy of Salmonella typhi infection was tested against Salm. typhi strain Ty2 after phagocytosis by human monocyte-derived macrophages. The macrophages, cultured in 96-well microtitre plates, were infected for 1 h at 37°C by opsonized Salm. typhi Ty2 at a bacteria-cell ratio of 9:1. When added to the infected macrophage monolayers, at one and ten times the MIC, ampicillin, ceftriaxone and pefloxacin appeared to be highly bactericidal (< 0.25 logl0 cfu/well after 20 h, against 4 log10 cfu/well in antibiotic-free controls). Trimethoprim-sulphamethoxazole was bactericidal at ten times the MIC, but not at the MIC. Chloramphenicol was mostly bacteriostatic at the concentrations tested. As a control, gentamicin (10mg/l) did not exhibit any significant antibacterial effect, indicating that most or all the bacteria recovered from lyied cells were intracellular. Other controls for phagocytosis were also performed with heat-killed Candida albicans. Our results seem to correlate with the known clinical effect of some antimicrobials in human Salm. typhi infection. The in-vitro assay described here may be useful for assessing the activity of antimicrobial agents against Salm. typhi infectio

SULT1A1 genotype, active and passive smoking, and breast cancer risk by age 50 years in a German case–control study

INTRODUCTION: Sulfotransferase 1A1 (encoded by SULT1A1) is involved in the metabolism of procarcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons, both of which are present in tobacco smoke. We recently reported a differential effect of N-acetyltransferase (NAT) 2 genotype on the association between active and passive smoking and breast cancer. Additional investigation of a common SULT1A1 genetic polymorphism associated with reduced enzyme activity and stability might therefore provide deeper insight into the modification of breast cancer susceptibility. METHODS: We conducted a population-based case–control study in Germany. A total of 419 patients who had developed breast cancer by age 50 years and 884 age-matched control individuals, for whom risk factor information and detailed smoking history were available, were included in the analysis. Genotyping was performed using a fluorescence-based melting curve analysis method. Multivariate logistic regression analysis was used to estimate breast cancer risk associated with the SULT1A1 Arg(213)His polymorphism alone and in combination with NAT2 genotype in relation to smoking. RESULTS: The overall risk for breast cancer in women who were carriers of at least one SULT1A1*2 allele was not significantly different from that for women with the SULT1A1*1/*1 genotype (adjusted odds ratio 0.83, 95% confidence interval 0.66–1.06). Risk for breast cancer with respect to several smoking variables did not differ substantially between carriers of the *2 allele and noncarriers. However, among NAT2 fast acetylators, the odds ratio associated with passive smoking only (3.23, 95% confidence interval 1.05–9.92) was elevated in homozygous carriers of the SULT1A1*1 allele but not in carriers of the SULT1A1*2 allele (odds ratio 1.28, 95% confidence interval 0.50–3.31). CONCLUSION: We found no evidence that the SULT1A1 genotype in itself modifies breast cancer risk associated with smoking in women up to age 50 years. In combination with NAT2 fast acetylator status, however, the SULT1A1*1/*1 genotype might increase breast cancer risk in women exposed to tobacco smoke

Activity of A-56268 (TE-031), a new macrolide, against Toxoplasma gondii in mice

The activity of A-56268 (TE-031), a new macrolide, was tested in a murine model of acute toxoplasmosis. All control animals died in 8 ± 1 days, while all mice treated with nine daily doses of A-56268 at 300 mg/kg, administered by gavage, survived. Moreover, 41.6% of the surviving mice were free from cerebral infection with Toxoplasma gondii, as assessed by brain subpassage. A-56268 is active against T. gondii in vivo, but further studies are needed to determine its usefulness in the treatment of human toxoplasmosi

First Extraction of Kaon Partonic Distribution Functions from Drell-Yan and J/ψJ/\psi Production Data

We present an analysis to extract kaon parton distribution functions (PDFs) for the first time using meson-induced Drell-Yan and quarkonium production data. Starting from the statistical model first developed for determining the partonic structure of spin-1/2 nucleon and later applied to the spin-0 pion, we have extended this approach to perform a global fit to existing kaon-induced Drell-Yan and $J/\psi$ production data. These data are well described by the statistical model, allowing a first extraction of the kaon PDFs. We find that both the Drell-Yan and the $J/\psi$ data favor a harder valence distribution for strange quark than for up quark in kaon. The kaon gluon distribution is further constrained by the $J/\psi$ production data. In particular, the momentum fraction carried by gluons is found to be similar for pion and kaon.Comment: 6 pages, 3 figures. arXiv admin note: text overlap with arXiv:2202.1254