Polyploidy and binuclearity are characteristics of the mammalian liver. Increasing polyploidisation occurs with age and after administration of various drugs and chemicals. This study was designed to examine the function of ploidy by addressing several questions: (1) Does the increase in size of polyploid hepatocytes have any physiological function by altering surface receptor expression such as intercellular adhesion molecule-1 (ICAM-1, CD54) or IFNgammaR? and (2) Do polyploid cells respond differently to inflammatory cytokines such as interferon gamma (IFNgamma)? We have developed a method to accurately measure the volume of live isolated hepatocytes using confocal microscopy and image analysis. Using flow cytometry, we have shown that the expression of ICAM-1 increases with increasing DNA content and IFNgammaR is not detectable on isolated mouse hepatocytes. Diploid (2n), tetraploid (4n) and octoploid (8n) hepatocytes were found to be equally susceptible to IFNgamma-induced apoptosis in vitro. Although the function of polyploidy remains unanswered, we have described some of the characteristics of polyploidy in isolated hepatocytes and in vitro.

The coordinating environments provided by the 1-(5,6-dimethylbenzimidazolyl)-3-benzimidazolyl-2-thiapropane (1), 1-(5,6-dimethylbenzimidazolyl)-3-benzimidazolyl-2-oxapropane (2), 1-(N-methyl)benzimidazolyl-3-benzimidazolyl-2-oxapropane (3), and 1,7-bis(benzimidazol-2-yl)-2,6-dithiaheptane (4) ligands for a series of soft-to-borderline metal ions have been demonstrated by crystallographic structure determination in the solid state, supplemented by multinuclear NMR studies in solution. Structures of [Zn(3)(H2O)(MeCN)](ClO4)2 ([C19H21N5O2Zn](ClO4)2, monoclinic, space group P21/c, a = 10.3247(11) Å, b = 11.0320(12) Å, c = 20.761(2) Å, β = 96.465(3)°, V = 2349.7(4) Å3, Z = 4), [Zn(1)Cl2]·CH3OH ([C18H18Cl2N4SZn]·CH4O, triclinic, space group P1̄, a = 9.0917(9) Å, b = 9.9186(10) Å, c = 12.2079(12) Å, α = 99.710(3)°, β = 94.252(2), γ = 95.598(3)°, V = 1075.3(2) Å3, Z = 2), [Hg(1)Br2]·CH3OH ([C18H18Br2HgN4S]·CH4O, triclinic, space group P1̄, a = 9.1956(12) Å, b = 9.9775(13) Å, c = 12.462(2) Å, α = 99.239(3), β = 97.676(3)°, γ = 94.036(3)°, V = 1113.4(3) Å3, Z = 2), [Cd(1)Cl2] ([C18H18CdCl2N4S], monoclinic, space group P21/n, a = 14.5219(11) Å, b = 8.5315(7) Å, c = 15.6182(12) Å, β = 92.063(2)°, V = 1933.7(3) Å3, Z = 4), and [Ag(4)](NO3) ([C19H20AgN4S](NO3), monoclinic, space group C2/c, a = 13.7339(3) Å, b = 17.2710(1) Å, c = 9.8866(2) Å, β = 115.399(1)°, V = 2118.4(1) Å3, Z = 4) have been determined. Ligand 3 provided the expected N2O donor set to Zn(II) forming part of a pseudo-trigonal bipyramidal coordinating environment, tentatively extrapolated to the Zn(II), Cd(II), and Hg(II) complexes of ligand 2 from 1H NMR studies. The thioether-bridged ligands (1 and 4) displayed a strikingly different coordination mode; in none of these structures was the thioether found to be coordinated to the central metal ion, resulting in pseudotetrahedral structures for the Zn(II) and Hg(II) complexes of ligand 1, a bis(chloro)-bridged dimeric five-coordinate complex of Cd(II) with ligand 1, and a near-linear coordination mode for the Ag(I) complex of ligand 4. No significant distinction in geometric parameters around the metal ions could be observed resulting from the introduction of asymmetry and a change of pK a within the bis(benzimidazole) ligands. Using 199Hg NMR spectroscopy, it was demonstrated that the thioether of ligand 1 did not coordinate in solutions of the 1:1 HgBr2 complex; negligible shifts of the signals corresponding to the aliphatic bridging protons in the 1H NMR spectra of ligand 1 when coordinated to Zn(II), Cd(II), and Hg(II) also suggested a noncoordinating behavior. Exchanges occurring in mixtures of HgBr2 and ligand 1 were examined using 199Hg, 13C, and 1H NMR. It is considered that there is little or no exchange occurring in a region of excess mercury on the 199Hg NMR time scale, and in a region of excess ligand 1 the 1/1 complex predominates.

the TSC1-TSC2 mutation ratio in our group of patients differs significantly from the 1:1 ratio previously predicted on the basis of linkage studies. There is an obvious paradox between the observed frequency of TSC1 mutations in familial cases and sporadic cases. An interestingly mild phenotype, observed in one of our TSC1 mutation carriers, led to the elaboration of a model that provides a plausible explanation for this paradox. We propose the presence of a very mildly affected patient group with TSC1-related disease who are not regularly detected by clinical diagnosis.

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