Robert Roos

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Polychlorinated biphenyls (PCBs) are among the most ubiquitously detectable 'persistent organic pollutants'. In contrast to 'dioxinlike' (DL) PCBs, less is known about the molecular mode of action of the larger group of the 'non-dioxinlike' (NDL) PCBs. Owing to the life-long exposure of the human population, a carcinogenic, i.e., tumor-promoting potency of(More)
We demonstrate that the class of languages accepted by deterministic one-counter machines, or DOCAs (a natural subset of the context-free languages), is learnable in polynomial time. Our learning protocol is based upon Angluin's concept of a "minimally adequate teacher" who can answer membership queries about a concept and provide counterexamples to(More)
Visna is a slow virus infection of sheep in which the characteristic pathological change is demyelination in foci of inflammation. The latter is thought to be the result of an immunopathological process directed against cellular and antigenic targets that have been difficult to define because of restricted viral gene expression. A new simultaneous detection(More)
The transformation of rifamycin S into rifamycins B and L was reinvestigated in order to establish more detailed pathways. Our results exclude rifamycin O as a common progenitor in the biosyntheses of rifamycins B and L. Rifamycins B and L are formed from rifamycin S (SV) by different pathways using different C3-precursors for the biosynthesis of their(More)
GOAL To clarify whether disturbances in the autonomic nervous system, reflected in abnormal cardiovascular reflexes, could explain symptoms of impaired heat regulation in patients with intestinal pseudo-obstruction. BACKGROUND Chronic intestinal pseudo-obstruction is a clinical syndrome characterized by diffuse, unspecific gastrointestinal symptoms due to(More)
PCB 180 (2,2',3,4,4',5,5'-heptachlorobiphenyl) is a persistent and accumulating polychlorinated biphenyl abundantly present in food and the environment. In this study, we used highly purified PCB 180 (dioxinlike impurities: 2.7 ng TEQ(WHO)/g PCB 180) in a 28-day toxicity study in young adult Sprague-Dawley rats. Male and female rats were given total doses(More)
PCB 180 is a persistent non-dioxin-like polychlorinated biphenyl (NDL-PCB) abundantly present in food and the environment. Risk characterization of NDL-PCBs is confounded by the presence of highly potent dioxin-like impurities. We used ultrapure PCB 180 to characterize its toxicity profile in a 28-day repeat dose toxicity study in young adult rats extended(More)
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