Knowledge of the potential dangers of exposure to radioactive substances and the insti tution of proper safety precautions have helped to reduce accidental exposures to radioactive substances. However, the carcinogenic hazard from them has by no means been eliminated, and, in spite of the exercise of reasonable care and the use of improved technics, accidents in the laboratory and indust ry may...

1. The pectic substances of apple have been extracted and separated into a pure pectinic acid and a neutral arabinan-galactan complex by precipitation of the acidic component with ethanol and with cetylpyridinium chloride. 2. The composition of the fractions has been determined. The pectinic acid contained galacturonic acid, arabinose, galactose, rhamnose, xylose and several trace sugars. 3. Tr...

Four separate examples have been discussed with the object of showing, first, how the concept of toxic amblyopia is an irrelevant one for modern ophthalmic research. This is the more true since one large category of the classical toxic amblyopias is not toxic at all and further adds to the confusion. It is suggested that rigorous criteria for the causative role of a particular substance in toxi...

Growth substances are compounds of a hormonalnature which, although present in the plant in extremely low concentrations, govern the life of the plant. 1\-1:uch regarding these substances is still obscure. Until recently it was thought that the chemical structure of all c~mpounds with growth substance activity (both natural and synthetic) conformed to two essential requirements, but the members...

The level of cellular differentiation of human oral, sulcular, and junctional epithelium was compared by immunohistochemical analysis of cell membrane-associated blood group-specific carbohydrates. Identification of the blood group A-specific carbohydrate and its two immediate precursor substances, type 2 chain H and N-acetyllactosamine. was accomplished by an indirect immunofluorescence techni...

Perfluoroalkyl substances (PFASs) are widely utilized manmade chemicals. Their properties have made them highly appreciated in a variety of industrial and consumer product applications, including fire-fighting foams, hydraulic fluids, as well as in cookware and food contact papers. However, some of the PFASs are highly persistent in the environment and their toxicological profiles are of concer...

Vitamin K comprises a group of substances, which are widespread in nature and are an essential co-factor in humans in the synthesis of several proteins that play a role in haemostasis and others that may be important in calcium homeostasis. The K vitamins all contain the 2-methyl-1,4-naphthoquinone (menadione) moiety, and the various naturally occurring forms differ in the alkyl substituent at ...