In order to develop new composite materials between reactive metals and polymers, it is proposed to place organic monomers at the metal/polymer phase boundary, which can be coupled by covalent/idc bonds to reactive centres of tbe metal substrate and later by covalent bonds to the polymer itself. As a Arst step, the model system iron/+ decanethiol (ndecylmercaptan, C,,H,,SH) has been investigated by AES and XPS. It is shown that the mercaptan binds to metallic clean iron surfaces through the sulphur atom, probably by cleavage of the S-H bond. The S 2p3,, peak has a binding energy of 162.4 f 0.2 eV. Anodic polarization and ageing in the laboratory atmosphere do not oxidize these chemisorbed molecules; the oxidation reactions of the substrate are suppressed too. After cyclovoltammetry (-1.0 V , , < U < + 0.6 VSH& better oriented chemisorbed molecules are packed more densely on top of the surface.

Cytarabine is intracellularly activated and correlations have been established between the pharmacokinetic behaviour of active metabolites and their antileukemic effect. Recently, a good response to high-dose treatment of leukemias has additionally been attributed to a so-called low deamination phenotype of cytarabine inactivation. Consequently, these findings would support plasma level monitoring of cytarabine and its metabolite uracil arabinoside in high-dose cytarabine regimens. This pharmacokinetic study presents data attempting to reevaluate these observations. Thirty-seven patients were treated by 3-h high-dose cytarabine infusions (9 patients 1000 mg/m2, 28 patients 3000 mg/m2) as part of their treatment for acute leukemia. Serial blood samples during and post infusion were analysed for cytarabine (araC) and its deamination product uracil arabinoside (araU) using HPLC with UV-detection. Considerable interindividual variation was observed in end-infusion plasma concentrations of araC (1000 mg/m2: 2.1-fold, 3000 mg/m2: 5.5-fold) and araU (1000 mg/m2: 2.7-fold, 3000 mg/m2: 2.9-fold). The median ratio of end infusion concentrations araU/araC (on a molar basis) was 5.6 (S.D. 3.0), extreme ratio values were 2 and 14. No differences of the araU/araC ratio were found between the two dosages used. Minimum plasma araC concentrations at the end of infusion were 10.5 micromol/l and 22.0 micromol/l at a dose of 1000 and 3000 mg/m2, respectively. In our European study population a "fast" deamination phenotype of cytarabine (araU/araC ratio > 14) was not be observed.

Iron surfaces, chemically modified by n‐decanethiol (n‐DMc), have been investigated in order to get a better understanding of the corrosion protection of reactive metals by organic coatings, as investigations of the phase boundary substrate/organic coating are possible only if just monolayers of an organic monomere are adsorbed onto the metal. Electron spectroscopic (XPS, AES) and electrochemical analyses (cyclovoltammetry, rotating ring‐disc‐electrode) have shown that a stable bond between iron and n‐DMc and a well defined orientation of the organic molecules towards the surface are only observed, if the thiol is adsorbed at an oxid free substrate. In this case the oxidation of the thiol by air to disulfide, sulfenate, and sulfonate is highly inhibited. Similar results are obtained regarding the electrode reactions like metal dissolution/passivation, and H+‐reduction in an Ar‐purged borate buffer (pH = 8.5). Only oxygen can be reduced on the modified surface with high rates, the kinetics being completely different from the one on clean iron surfaces. It is proposed, that as part of the O2‐reduction the thiol is transformed into disulfide, which then catalyses the oxygen reduction but still inhibits the rate of metal dissolution and H+‐reduction. After prolonged O2‐reduction the disulfide is oxidized to sulfonate, which then desorbs from the metal surface.