Cell-surface events for metallothionein-1 and heme oxygenase-1 regulation by the hemopexin-heme transport system

A model has been developed for the hemopexin receptor-mediated heme transport system based on iron uptake in yeast. Two steps are required: reduction followed by oxidation by a multi-copper-oxidase. Furthermore, in the hemopexin system, the surface redox events have been linked with gene regulation. The impermeable Cu(I) chelator bathocuproinedisulfonate (BCDS) is shown here to abrogate heme oxygenase-1 (HO-1) mRNA induction by heme-hemopexin. A role for Cu(I) in the regulation of HO-1 and MT-1 (Sung et al., 1999) by hemopexin supports the participation of electron transport processes at the cell surface as does competition by the reductase activator, ferric citrate, which inhibits the induction of MT-1 and HO-1 mRNA by heme-hemopexin. There is a key role for the hemopexin receptor because neither ferric citrate nor iron-transferrin alone regulates MT-1 or HO-1. Cell-surface copper is the first molecule to link the concomitant regulation of HO-1 and MT-1 by the hemopexin receptor. In addition, cytochrome b5 and cytochrome b5 reductase are implicated here in the response of cells to heme-hemopexin. Reduction of one or more electron donors of the reductase and oxidation of the electron acceptor, b5 heme, leads to gene regulation, but only when heme-hemopexin is bound to its receptor. Protein kinase cascades, including JNK, are activated by the hemopexin receptor itself upon ligand binding but are modulated by a Cu(I)-dependent process likely to be heme uptake.     

Vinyl polymerization. 120. Mutual copolymerization of p-substituted styrenes through radical mechanism

The radical mutual copolymerization of p-substituted styrenes, such as p-methoxy-, p-chloro-, p-bromo-, p-cyanostyrene, and styrene was carried out with one another at 30°C. in the dark. As initiator, azobisisobutyronitrile was used. The plots of the copolymerization rates against HAMMETT 's σ values showed no linear relationships and the concave curves were obtained therefrom. The relative reactivities of p-substituted styrenes with a definite p-substituted polystyryl radical, which were shown by the reciprocal of monomer reactivity ratio r₁, were plotted against σ values and concave curves were also obtained. The relative reactivities of p-substituted polystyryl radicals with p-substituted styrene were calculated from the ratios r₂ and the propagation rate constants in homopolymerization. the plots of them against σ values gave straight lines with different ρ values, according to the polarity of substituents. These results suggest that polar structures in transition state affected markedly the copolymerization rates. The effect of substituents on resonance stabilization was also quantitatively estimated.     

Essential role of rho kinase in the ca2+ Sensitization of Prostaglandin F2α-Induced Contraction of Rabbit Aortae

Although the prostate gland is a rich source of α1-adreno- (α1-AR) and m1-cholino receptors (m1-AChR), the membrane processes associated with their activation in glandular epithelial cells is poorly understood. We used the whole-cell patch-clamp technique to show that the agonists of the respective receptors, phenylephrine (PHE) and carbachol (CCh), activate cationic membrane currents in lymph node carcinoma of the prostate (LNCaP) human prostate cancer epithelial cells, which are not dependent on the filling status of intracellular IP₃-sensitive Ca²⁺ stores, but directly gated by diacylglycerol (DAG), as evidenced by the ability of its membrane permeable analogue, OAG, to mimic the effects of the agonists. The underlying cationic channels are characterized by the weak field-strength Eisenman IV permeability sequence for monovalent cations ( P _K(25) > P _Cs(4.6) > P _Li(1.4) > P _Na(1.0)), and the following permeability sequence for divalent cations: P _Ca(1.0) > P _Mg(0.74) > P _Ba(0.6) > P _Sr(0.36) > P _Mn(0.3). They are 4.3 times more permeable to Ca²⁺ than Na⁺ and more sensitive to the inhibitor 2-APB than SK&F 96365. RT-PCR analysis shows that DAG-gated members of the transient receptor potential (TRP) channel family, including TRPC1 and TRPC3, are present in LNCaP cells. We conclude that, in prostate cancer epithelial cells, α1-ARs and m1-AChRs are functionally coupled to Ca²⁺-permeable DAG-gated cationic channels, for which TRPC1 and TRPC3 are the most likely candidates.     

Vinyl polymerization. 294. Decomposition of tetramethyltetrazene in the presence of p-substituted benzyl chlorides

A study was made of the polymerization of acrylonitrile in dimethylformamide (DMF) initiated by the binary systems of tetramethyltetrazene (TMT) and p-substituted benzyl chlorides. The polymerization rate increased linearly with the σ-constants of substituents as electron-releasing groups were introduced to the phenyl ring of benzyl chloride. In order to elucidate the initiation mechanism of the polymerization, a kinetic investigation was also undertaken of the decomposition of TMT in the presence of p-substituted benzyl chlorides in DMF. The decomposition rate was first-order in TMT and first-order in p-substituents benzyl chloride. The decomposition rate also increased with the σ constants of substituents as electron-releasing groups were introduced. On the basis of the results, the initiation mechanism for the polymerization was discussed.     

Morphometric comparison of human nerve cells: pyramidal motor system

We compared morphological and morphometric data on various motor neurons in the human pyramidal system using the modified Klüver-Barrera staining method with extremely minimized shrinkage ratio and an image-analyzer. We classified motor neurons in the human pyramidal system into three groups according to the measurement data. This report may be of interest to better understand the process of nerve conduction in the human pyramidal system.