The chromatin structure of rat hepatocytes fixed in situ was investigated in thin sections selectively stained for DNA with the Feulgen-like osmium-ammine reaction. Visualization of the chromatin structure was facilitated by the dispersal that occurred in the chromatin of regenerating rat hepatocytes at 24 h after partial hepatectomy. Our results show that repeating subunits were present both i...

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Synopsis The structure of a cisplatin-modified DNA dodecamer duplex containing a 1,2-cis-{Pt(NH 3) 2 } 2+-d(GpG) cross-link has been determined at 1.77-Å resolution. Improved electron density reveals new features not seen in the originally published 2.6 Å structure. Abstract We...

Mixed amine/ammine motifs are important features in newer generation platinum anticancer agents, including the Pt(IV) prodrug satraplatin. One synthetic route that can be used to access platinum molecules with such structures exploits the trans effect during NH3-mediated cleavage of iodo-bridged platinum(II) dimers of the form [Pt(Am)I(μ-I)]2, where Am is an amine. A clear picture of the nature...

Platinum(IV) compounds like oxoplatin (cis, cis, trans-diammine-dichlorido-dihydroxido-platinum(IV)) show increased stability and therefore can be applied orally. In a panel of 38 human cancer cell lines this drug induced S-phase arrest and cell death with IC(50) values 2.5-fold higher than cisplatin. Oxoplatin may be converted to cisplatin by intracellular reducing agents, however, exposure to...

The dependence of the reaction entropies, ASo,, for simple M(III/II) redox couples (M = Ru, Fe, Os, Cr) upon the nature of the ligands and the solvent is examined with a view toward correlating ASo, with simple physical parameters. For couples containing ammine, ethylenediamine, polypyridine, cyclopentadiene, or pseudohalide ligands, ASo, in a given solvent is found to correlate well with (Zo: ...

An adaptation of the Feulgen procedure to visualise DNA at the ultrastructural level, using osmium ammine instead of Schiff reagent, was applied to ultrathin sections of rabbit epididymal spermatozoa, known to display increasing chromatin compaction as they progress through the epididymis. In contrast with the somatic cell nuclei of the epididymal epithelium, which display classical staining, t...

Various Pt(IV) diazides have been investigated over the years as light-activatable prodrugs that interfere with cell proliferation, accumulate in cancer cells and cause cell death. The potencies of the complexes vary depending on the substituted amines (pyridine=piperidine>ammine) as well as the coordination geometry (trans diazide>cis). Light-activated Pt(IV) diazides tend to be less specific ...

Practical chemistry courses at universities very frequently propose the synthesis and characterization of [Co(CO3)(NH3)4]NO3, but this goal is never achieved since students only obtain the hemihydrated form. The anhydrous form can be prepared, however, and its structure is presented here. Similar to the hemihydrate form, the anhydrous phase contains the Co(III) ion in an octahedral O2N4 coordin...

In several recent studies we have observed that stepwise encapsulation of simple redox partners by weakly interacting molecular hosts can exert substantial kinetic and/or energetic effects upon thermal (self exchange) and/or optical (intervalence) electron transfer (ET) reactions.1-3 The previous studies featured encapsulation via either hydrogen bonding (ammine ruthenium guests with crown ethe...