Imperial Chemical Industries

About: Imperial Chemical Industries is a based out in . It is known for research contribution in the topics: Alkyl & Catalysis. The organization has 8189 authors who have published 7809 publications receiving 190252 citations. The organization is also known as: Imperial Chemical Industries Ltd.

The unique role of rodents in the detection of possible human carcinogens and mutagens.

Abstract: Some of the probable reasons underlying the observation that not all chemicals shown to be genotoxic in vitro are capable of eliciting tumours in rodents or humans are discussed using appropriate examples. It is suggested that a substantial proportion of the resources currently available for conducting rodent carcinogenicity bioassays should be employed in the short-term evaluation in vivo of some of the many hundreds of chemicals recently defined as genotoxic in vitro, rather than in the protracted evaluation of a few chemicals, often of unknown activity in vitro, for carcinogenicity. A decision tree approach to the evaluation of chemicals for human mutagenic/carcinogenic potential is presented which is at variance with the construction and philosophy of many of the current legislative guidelines. The immediate need for the adoption of one of the available short-term in vivo liver assays, and/or the development of a short-term in vivo rodent assay capable of concomitantly monitoring different genetic end-points in a range of organs or tissues is emphasized.

The Assimilation of Nitrogen from Ammonium Salts and Nitrate by Fungi

Abstract: SUMMARY 1. The assimilation of inorganic nitrogen by Scopulariopsis brevicaulis and some physiologically similar species has been studied. Their failure to assimilate completely from ammonium sulphate has been shown to be due to the fall in pH of the medium induced by the initial uptake of ammonia. 2. Complete assimilation of ammonia takes place in the presence of the neutral salts of each of thirteen organic acids investigated. The organic acids act prima rily through their buffering effect which prevents or slows down the fall in pH. They are not specifically required for ammonia assimilation by these fungi and can be effectively replaced by certain inorganic buffers. 3. The influence of several external factors on the rate of assimilation of ammo nia, nitrate, and nitrite has been studied in S. brevicaulis. In corresponding condi tions the mycelium assimilates ammonia more rapidly than .nitrate over a wide range of conditions. 4. Ammonia, even in very low concentration, completely suppresses nitrate assimilation when both sources of nitrogen are present together. Nitrite, how ever, is assimilated simultaneously with ammonia. It is therefore concluded that ammonia blocks the reduction of nitrate to nitrite by the fungus. 5. The suppression of nitrate assimilation in the presence of ammonia is com mon to many mould fungi besides S. brevicaulis, and is believed to have adaptive significance in natural habitats. 6. The nitrate-reducing and assimilating system is formed, even when S. brevi caulis is grown in complete absence of nitrate (ammonia medium with organic acid). It comes into action rapidly when the inhibiting effect of ammonia is removed. Similarly, nitrate-grown mycelium is capable of assimilating ammonia at maximal rate without any adaptive lag.

Young Scientists Award Lecture 1981: The Identification of an Accumulation System for Diamines and Polyamines Into the Lung and Its Relevance to Paraquat Toxicity

Abstract: The energy dependent accumulation of the herbicide paraquat into the lung is known to be a major factor responsible for the selective toxicity of paraquat to this organ. The studies reported in this paper were designed to examine the hypothesis that the transport process responsible for the accumulation of paraquat is present to accumulate endogenous substrates from the plasma.