Characterization of sorption of endosulfan isomers and chlorpyrifos on container walls using mixed solvent systems.

The reliability of sorption data for organic contaminants with low water solubility has generated great concern because of the variability in the literature of the soil-water partition coefficient (K(OC)) values for these compounds. In particular, sorption on container walls in aqueous systems when measuring the sorption coefficient, K(D) (used to calculate K(OC) values), for strongly hydrophobic compounds (SHOCs) is a potential source for discrepancies in the K(OC) values. In this study, we eliminated sorption on container walls when measuring sorption of three halogenated compounds (alpha-endosulfan, beta-endosulfan, and chlorpyrifos) using mixed solvents. Various mixtures of methanol and water were used. Sorption experiments were designed using polytetrafluoroethylene (Teflon)-lined centrifuge tubes and a high-performance liquid chromatography (HPLC) syringe. Solution sample analysis was performed using HPLC equipped with a UV diode array detector and C-18 column at a wavelength of 214 nm, with acetonitrile/water (80:20, v/v) as the mobile phase. The solvophobic model was used to calculate the percent recovery (% R(M)) in water of the test compounds. Our results show that there is considerable sorption on container walls for the three chemicals at volume fractions of methanol (f(c) < 0.4). The data show that, in aqueous systems, percent recoveries for alpha-endosulfan, beta-endosulfan, and chlorpyrifos are 48, 45, and 61, respectively. Thus, to generate reliable sorption data for alpha-endosulfan, beta-endosulfan, and chlorpyrifos and other SHOCs, experiments may be conducted using Teflon-lined centrifuge tubes and HPLC syringes at volume fractions of methanol (f(c) >or= 0.5).

Malaria - The obstetrician's dilemma: malaria in pregnancy: treatment problems

Malaria in pregnancy is a common parasitic infection in Uganda and East Africa in general. The severity of infection depends on the patients immune status; and is worse in the primigravidae and the non-immune migrating to endemic areas. It may produce intrauterine growth retardation or complications in the mother such as cerebral malaria; acute pulmonary oedema; renal failure and in some cases is responsible for several autoimmune phenomena. A number of drugs have been used as the mainstay of treatment but the picture has become complicated by the emergence of resistant strains. Some drugs such as the sulphonamides and trimethoprim which would be useful in overcoming this resistance are unsuitable for use especially in late pregnancy because of adverse effects on the newborn. Newer drugs such as halofantrine and artemisinin (and other ginghaosu derivatives) have been tested and found to be effective against chloroquine resistant malaria. They have unfortunately been found to have either embryotoxic or gonadotoxic effects in laboratory animals. Ethical problems limit the ability of researchers to assess these adverse effects in clinical practice in obstetrics; thus presenting the obstetricians with a clinical dilemma in resistant forms of the disease. (This was a paper presented at the Uganda Medical Association; Lake View Hotel; Mbarara)

Malaria - The obstetrician's dilemma: malaria in pregnancy: treatment problems

Malaria in pregnancy is a common parasitic infection in Uganda and East Africa in general. The severity of infection depends on the patients immune status; and is worse in the primigravidae and the non-immune migrating to endemic areas. It may produce intrauterine growth retardation or complications in the mother such as cerebral malaria; acute pulmonary oedema; renal failure and in some cases is responsible for several autoimmune phenomena. A number of drugs have been used as the mainstay of treatment but the picture has become complicated by the emergence of resistant strains. Some drugs such as the sulphonamides and trimethoprim which would be useful in overcoming this resistance are unsuitable for use especially in late pregnancy because of adverse effects on the newborn. Newer drugs such as halofantrine and artemisinin (and other ginghaosu derivatives) have been tested and found to be effective against chloroquin resistant malaria. They have unfortunately been found to have either embryotoxic or gonadotoxic effects in laboratory animals. Ethical problems limit the ability of researchers to assess these adverse effects in clinical practice in obstetrics; thus presenting the obstetricians with a clinical dilemma in resistant forms of the disease