Reciprocal effects of platinum and lead on the water household of poplar cuttings

In order to study the accumulation rates and effects of platinum as influenced by lead, experiments were performed with poplar cuttings in a growth chamber. The heavy metals were added at a final concentration of 34.8 ppb each to nutrient solutions as PtCl₄ and Pb(NO₃)₂. The variants were 1) control; 2) permanent Pt treatment for 6 weeks; 3) pretreatment with Pt plus subsequent treatment with Pb (three weeks each), and 4) heavy metal application in inverse order to variant 3. The experiments revealed that platinum accumulates in the roots of poplar cuttings to a higher degree than lead. It is translocated from the roots to other plant parts to an extremely low degree. Lead is displaced from the roots by subsequent Pt treatment. Insoluble platinum was found to be associated especially on the cell walls of the rhizodermis and exodermis of the root tips. Accumulation of platinum in the roots leads to a gradual depletion of the plants’ water supply. The disturbance of the water household causes a reduction of the transpirational surface, lowered transpiration rates and enhanced root growth. All these alterations are induced as a means of coping water stress. From the results of this experiment, the conclusion can be drawn that, under the chosen experimental conditions, platinum manifests a higher toxicity than lead in plant roots because of its higher accumulation rates.     

Tumorlektinologie —Status und Perspektiven klinischer Anwendung

A detailed knowledge of the mechanisms of molecular recognition is a prerequisite to rationally improved diagnostic and therapeutic procedures in diseases. In addition to sequences of amino acids, carbohydrate structures apparently store biological information that is thought to be relevant for physiologically important processes. Such ligands, namely the carbohydrate part of cellular glycoconjugates, can be recognized by specific endogenous binding proteins like lectins. If their presence can be reliably ascertained and correlated to the clinical course of the disease, e.g. in oncology, lectinology may help to define a yet undisclosed role for this class of proteins in tumor progression and spread.     

Effective synthesis of sulfate metabolites of chlorinated phenols

Chlorophenols are an important class of persistent environmental contaminants and have been implicated in a range of adverse health effects, including cancer. They are readily conjugated and excreted as the corresponding glucuronides and sulfates in the urine of humans and other species. Here we report the synthesis and characterization of a series of ten chlorophenol sulfates by sulfation of the corresponding chlorophenols with 2,2,2-trichloroethyl (TCE) chlorosulfate using N,N-dimethylaminopyridine (DMAP) as base. Deprotection of the chlorophenol diesters with zinc powder/ammonium formate yielded the respective chlorophenol sulfate ammonium salts in good yield. The molecular structure of three TCE-protected chlorophenol sulfate diesters and one chlorophenol sulfate monoester were confirmed by X-ray crystal structure analysis. The chlorophenol sulfates were stable for several months if stored at −20 °C and, thus, are useful for future toxicological, environmental and human biomonitoring studies.