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- Nakao, Naoyuki, et al.
(författare)
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Overexpressing Cu/Zn superoxide dismutase enhances survival of transplanted neurons in a rat model of Parkinson's disease
- 1995
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Ingår i: Nature Medicine. - 1078-8956. ; 1:3, s. 31-226
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Tidskriftsartikel (refereegranskat)abstract
- A high survival rate of grafted dopamine neurons is crucial for reversing neurological deficits following brain tissue transplantation in Parkinson's disease. For unknown reasons the survival rate of transplanted dopamine neurons is only around 10% in experimental animals. The hypothesis that oxidative stress causes the loss of transplanted neurons was tested by grafting neurons from transgenic mice that overexpress Cu/Zn superoxide dismutase. Compared with the survival of those taken from non-transgenic littermates, the survival was 4 times higher for the transgenic dopamine neurons with a concomitant more extensive functional recovery. The results provide direct support for the free radical hypothesis of dopaminergic neuron death in brain tissue grafting.
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- Sugiura, K., et al.
(författare)
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The importance of magnetic coupling through atoms with large spin densities - Structure and magnetic properties of meso-tetrakis-(4'-tert-butylphenyl)porphinatomanganese(III) hexacyanobutadienide, Mn(III)TtBuPP (+) C-4(CN)(6) (.-)
- 1997
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Ingår i: Chemistry-a European Journal. ; 3:1, s. 138-142
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Tidskriftsartikel (refereegranskat)abstract
- [Mn(III)TtBuPP](+)[C-4(CN)(6)](.-) . [(MnTrBuPP)-Tr-III = meso-tetrakis(4'-tert-butylphenyl)porphinatomanganese(III)] has been prepared and structurally and magnetically characterized. The uniform, linear-chain (1-D) coordination polymer comprises alternating cations and anions. The bond lengths in planar ion [C-4(CN)(6)](.-) are 1.377(10) (CC-CC), 1.418(7) (C-CCC), 1.414 (C-CN), 1.457 (C-CNMn), 1.150 (C=N), and 1.134 Angstrom (C=NMn). The Mn-N-C angle is 172.3 (4)degrees, and the intrachain Mn ... Mn separation is 10.655 Angstrom. Each [C-4(CN)(6)](.-) unit is bonded to two Mn-III atoms through the interior nitrogen atoms in a times-mu(2)-N-sigma manner with N-Mn bond lengths of 2.353 Angstrom. The (CN) absorptions are at 2217 (w,br) and 2190 (m) cm(-1). Above 50 K the magnetic susceptibility of [Mn(III)TtBuPP](+)[C-4(CN)(6)](.-) can be fitted to the Curie-Weiss expression, chi proportional to 1/(T - theta), with an effective theta of -13 K. This is consistent with weak antiferromagnetic coupling, which is in contrast to the effective theta of + 67 K for the uniform chain [(MnOEP)-O-III](+)[C-4(CN)(6)](.-) [OEP = octaethylporphinato]. Here, the [C-4(CN)(6)](.-) units are bonded to the Mn-III centers through endo CN nitrogen atoms in a similar trans-mu(2) manner. Density functional theory MO calculations reveal that the spin density of the CN nitrogen atom bound to [Mn-III- TtBuPP](+) (0.019 mu(B) Angstrom(-3)) is significantly lower than that of the N atom bound to [(MnOEP)-O-III]+ (0.102 mu(B) Angstrom(-3)). This is consistent with the reduced spin coupling observed for [Mn(III)TtBuPP](+)[C-4(CN)(6)](.-) with respect to [(MnOEP)-O-III](+)[C-4(CN)(6)](.-), as evidenced by the lower theta value. The different orientations of the [C-4(CN)(6)](.-) units-almost perpendicular (84.72 degrees) for [Mn(III)TtBuPP](+)[C-4(CN)(6)](.-) and substantially tilted (32.1 degrees) for [(MnOEP)-O-III](+)[C-4(CN)(6)](.-)-may also contribute to the poorer overlap and weaker spin coupling. Hence, binding between sites with large spin densities is needed to stabilize strong ferromagnetic coupling.
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