Uniform procedure of (1)H NMR analysis of rat urine and toxicometabonomics Part II: comparison of NMR profiles for classification of hepatotoxicity.

A procedure of nuclear magnetic resonance (NMR) urinalysis using pattern recognition is proposed for early detection of toxicity of investigational compounds in rats. The method is applied to detect toxicity upon administration of 13 toxic reference compounds and one nontoxic control compound (mianserine) in rats. The toxic compounds are expected to induce necrosis (bromobenzene, paracetamol, carbon tetrachloride, iproniazid, isoniazid, thioacetamide), cholestasis (alpha-naphthylisothiocyanate (ANIT), chlorpromazine, ethinylestradiol, methyltestosterone, ibuprofen), or steatosis (phenobarbital, tetracycline). Animals were treated daily for 2 or 4 days except for paracetamol and bromobenzene (1 and 2 days) and carbon tetrachloride (1 day only). Urine was collected 24 h after the first and second treatment. The animals were sacrificed 24 h after the last treatment, and NMR data were compared with liver histopathology as well as blood and urine biochemistry. Pathology and biochemistry showed marked toxicity in the liver at high doses of bromobenzene, paracetamol, carbon tetrachloride, ANIT, and ibuprofen. Thioacetamide and chlorpromazine showed less extensive changes, while the influences of iproniazid, isoniazid, phenobarbital, ethinylestradiol, and tetracycline on the toxic parameters were marginal or for methyltestosterone and mianserine negligible. NMR spectroscopy revealed significant changes upon dosing in 88 NMR biomarker signals preselected with the Procrustus Rotation method on principal component discriminant analysis (PCDA) plots. Further evaluation of the specific changes led to the identification of biomarker patterns for the specific types of liver toxicity. Comparison of our rat NMR PCDA data with histopathological changes reported in humans and/or rats suggests that rat NMR urinalysis can be used to predict hepatotoxicity.     

Oestrogen modulates cardiac ischaemic remodelling through oestrogen receptor-specific mechanisms

Aim: Observational and clinical studies suggest different responses upon sex hormone replacement therapy in ischaemic heart disease. Few studies, however, have examined the impact of oestrogen receptor‐dependent mechanisms on the extent of injury after myocardial infarction (MI). Therefore, we set out to evaluate the effect of oestrogen (E2) replacement on infarct size and remodelling, and the respective role of the oestrogen receptors (ER)α and ‐β in this process, using ERα‐ and ERβ‐deficient mice. Methods: Wild type (WT) (ERα^+/+ and ERβ^+/+), ERα‐deficient (ERα^−/−) and ERβ‐deficient (ERβ^−/−) mice were ovariectomized and subsequently supplemented with E2 or placebo using subcutaneous 60‐day release pellets. MI was induced by left coronary artery ligation. Two weeks following MI, haemodynamic function was assessed and infarct size was determined. Results: There was no significant difference in infarct size between E2‐ or placebo‐treated WT (ERα^+/+ and ERβ^+/+) mice. Surprisingly, E2 treatment did result in smaller infarct sizes in ERα^−/− mice, but increased the infarct size in ERβ^−/− mice. Increase of the left ventricular mass post‐MI was significantly larger in the E2‐treated ERα^−/− animals compared with placebo‐treated animals. E2 treatment also significantly increased post‐MI mortality in ERα^+/+, ERβ^+/+ and ERα^−/− animals, but not in ERβ^−/− mice. Conclusions: Although E2 modulates the infarct size in ERα^−/−, it also appears to be responsible for the higher mortality following MI. ERβ appears to be the receptor involved in the modulating effects of E2 in the infarcted heart.     

Ethical issues surrounding studies with vulnerable populations: a case study of South African street children

Researchers who investigate social and economic determinants of health often interact with vulnerable and marginalized populations. Great care must be taken to conduct research studies involving vulnerable persons in a manner consistent with accepted ethical principles in order to protect participants from exploitation, to build capacity, and to promote wellbeing. Children form a particularly vulnerable group, especially those who do not enjoy the protection of parents or guardians. METHODS: A research project which studied South African Sunnyside's street children was used as a case study to illustrate ethical issues surrounding research with vulnerable populations. DISCUSSION: The participants in the case study lacked the age of majority and were without any legal guardian. The researchers experienced considerable difficulty in obtaining ethical approval to conduct the study. The street children, at first, were not allowed to give informed consent for the study because of their minor age. Ethical principles of autonomy, disclosure, competence and understanding, consent and voluntariness, beneficence and non-maleficence, and justice are described and applied to this case study involving street children in a South African neighbourhood. It is suggested that by working within an ethical framework, the safety of research participants will be assured and the quality of the research will be enhanced.     

Infection of Escherichia coli K-12 by bacteriophage φX-174

By several different biochemical tests, a previously described isolation procedure was shown to produce host-range mutants of φX-174 capable of infecting some strains of Escherichia coli K-12. One of these mutants (φXK-9) has a wide host range which includes E. coli C, B, and Shigella Y6R. By fragment mapping the site of the host-range mutation was shown to be in gene F.