H. Van Genderen

The Induction of Renal Tumours by Feeding of Basic Lead Acetate to Rats

ImagesFigs. 6-7Figs. 3-5

Morphological effects of the flavone isovitexin in a non-glycosylating genotype ofSilene pratensis (Caryophyllaceae)

Genetic studies have shown that the unglycosylated flavone isovitexin causes an aberrant petal morphology inSilene pratensis. Scanning electron micrographs show that the individuals with free isovitexin have abnormal upper epidermal cells.

The Production of Skin Tumours in Mice by Oral Treatment with Urethane, Isopropyl-N-phenyl Carbamate or Isopropyl-N-chlorophenyl carbamate in Combination with Skin Painting with Croton Oil and Tween 60

The Production of Skin Tumours in Mice by Oral Treatment with Urethane, Isopropyl-N-phenyl Carbamate or Isopropyl-N-chlorophenyl carbamate in Combination with Skin Painting with Croton Oil and Tween 60

Hexachlorobutadiene residues in aquatic fauna from surface water fed by the river rhine

Hexachlorobutadiene (HCBD) was identified as a component of the residue mixture of chlorinated hydrocarbons in fish from inland waters fed by the Rhine, particularly in the Ketelmeer. The residue level in fish is related to the fat content; no bioaccumulation in the food chain to higher trophic levels was observed. HCBD concentrations in the water of the Ketelmeer appeared to be three orders of magnitude lower than those found in aquatic animals.

Über die chronische Verträglichkeit von Annattofarbstoff

ZusammenfassungEs wurden toxikologische Untersuchungen mit zwei verschiedenen fettlöslichen Annatto-Präparaten durchgeführt, welche vorwiegend für die Färbung von Margarine benutzt werden, und einem wasserlöslichen Annatto-Präparat für die Käsefärbung.In akuten Versuchen mit Ratten, semichronischen Fütterungsversuchen mit Ratten und Schweinen und in chronischen Versuchen über die ganze Lebensdauer und mehrere Generationen mit Ratten, konnte keine schädigende Wirkung dieser Präparate in der gegebenen Dosierung festgestellt werden. Zwischen Dosierung und den in Margarine und Käse benutzten Mengen besteht eine genügend große Sicherheitsspanne. In chronischen Fütterungs- und subcutanen Injektionsversuchen bei Ratten und Mäusen erwiesen sich diese Präparate als nicht carcinogen.

Toxicology of the herbicide dichlobenil (2,6-dichlorobenzonitrile) and its main metabolites

A review of the toxicology of dichlobenil presents the results of acute tests in rats, mice and rabbits, short-term tests in rats, pigs and rabbits, long-term and reproduction studies in rats and a test for teratogenicity in mice. The compound is more toxic on acute administration to rabbits than to rats, but this difference in sensitivity is not apparent in short-term tests. A single lethal dose in the rabbit produces liver necrosis, but enzyme studies seem to indicate that sublethal doses cause little or no liver damage. The formation of phenolic metabolites has been demonstrated in both rats and rabbits. Various criteria show that these substituted phenols are active uncouplers of oxidative phosphorylation. The possible connexion between the liver necrosis found in the rabbit and the uncoupling action of the metabolites of dichlobenil is discussed.

Triterpenes and alkanes in developing variegated and albino leaves of Ilex aquifolium L. (Aquifoliaceae).

Abstract The alkane contents and composition of Ilex aquifolium cuticular wax layers are similar in green and albino leaf parts of the same age. This in contrast to the triterpene content of the cuticle which is low in albino leaves and leaf parts. The most abundant alkanes found on mature leaves are C29H60 and C31H62 and C33H68. The triterpenes present in the epicuticular wax and/or cuticle are α-amyrin, β-amyrin, uvaol, erythrodiol, ursolaldehyde, oleanolaldehyde, ursolic acid, oleanolic acid and finally two esters identified as: urs-12-en-28-oic acid methylester and ursa-2,12-dien-28-oic acid methylester. The latter substance was found especially in albino leaves and leaf parts.

Long chain pentyl- and hexyl-esters and other lipoids in leaf wax of Ilexaquifolium L. (Aquifoliaceae)

Abstract The lipoid-fraction of the surface-wax of young leaves of Ilex aquifolium, mainly consists of alkanes and esters of long-chain fatty acids. One series of pentyl-esters, and two series of hexyl-esters were found. Since the esters disappear as the leaves grow mature, they can be regarded as leaf expansion markers. It seems possible that the alkanes are synthesized from these fatty acid-esters, as they replace them in older leaves.

Globular, crystal- and clew-like structures in the epidermis cells of mutants ofSilene pratensis unable to glycosylate isovitexin

SummaryEpidermis cells ofSilene pratensis mutants unable to glycosylate isovitexin show a variety of internal and structural aberrations. In cells of mutants able to glycosylate isovitexin, the flavone-glycoside containing vacuole appears to occupy the whole cell. In cells of mutants unable to glycosylate isovitexin either globular, or crystal-like, or clew-like structures are present. These inclusions consist for the largest part of isovitexin. The nucleus has often moved to the sidewalls and is frequently degenerated. The shape os the cells, especially those with a clew-like structure, is often bladder-like swollen.

Risks from Combined Exposures to Different Chemicals

Publisher Summary This chapter discusses the risks from combined exposures to different chemicals. The problem of mixtures of different chemicals in the environment is particularly important in surface water as the aquatic organisms are exposed to the joint action of the mixture. The chapter discusses a study for this problem in a series of experiments of fish. In the case of complex mixtures as in polluted surface water, the occasional occurrence of pairs of compounds with interaction (resulting in potentiation or antagonism) is not very important. What remains in the first place is simple similar action for compounds with the same site of action, as when more than one organophosphate is present. In the case of simple similar action, it is most convenient to refer to a fixed standard response level for both the single compounds and the mixture. In this case it was the LC50 for fish. In the second place, there is the independent action for mixtures of differently acting compounds, as for example with a mixture of dieldrin, parathion, and fluoroacetic acid. In the case of independent action of compounds in a mixture, two extreme possibilities may be distinguished. In the first possibility, the same fishes, which are more sensitive to one of the compounds, are also more sensitive to all the other compounds. If the sensitivity for the different compounds is random among the fishes, or rather if there is no correlation (r=O), than each component will contribute to the total toxicity of the mixture in accordance with its own probability of killing at its given concentration and toxicity. The probability of surviving the mixture can be calculated as the product of the probabilities of survival for each component.