Metabolism of tetrahydrobiopterin: Its relevance in monoaminergic neurons and neurological disorders

(6R)‐L‐erythro‐5,6,7,8‐tetrahydrobiopterin (BH4) is an essential cofactor for aromatic amino acid hydroxylases, such as phenylalanine hydroxylase (PAH), tyrosine hydroxylase (TH), tryptophan hydroxylase, and nitric oxide synthase, which catalyze physiologically important reactions in mammals. The biosynthesis and metabolism of BH4 is usually studied mostly in the liver and only slightly in the brain, as the BH4 level in the liver is relatively high because BH4 is required for the reaction of PAH. We found that GTP (guanosine triphosphate) cyclohydrolase I, an enzyme for the biosynthesis of BH4, is a causative gene for DOPA (3,4‐dihydroxyphenylalanine)‐responsive dystonia (also called Segawa's disease), and that partial deficiency of BH4 leads to the dysfunction of the nigrostriatal dopaminergic neurons without hyperphenylalaninemia. We analyzed BH4‐deficient mice that were produced by disruption of a BH4‐synthesizing gene by a gene‐knockout technique. We found that the protein amount of TH was highly dependent on the amount of BH4, especially in nerve terminals. Our research suggests that BH4 metabolism in the brain should be different from that in the liver, and that altered metabolism of BH4 should lead to neuropsychiatric disorders including Parkinson's disease. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 378–385; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20166     

Development of heterodyne detection of dynamic light scattering enhanced by the Talbot effect for the size measurement of nanoparticles.

A new type of dynamic light scattering method for the size measurement of nanoparticles was developed using a transmission grating. A sample cell was located behind the grating, and light was incident from the grating side. The scattered light by a solution with nanopariticles was mixed with diffracted light by the grating, and the mixed signal was detected; namely, the diffracted light was used as reference light for heterodyne detection. It was confirmed that the S/N ratio of the autocorrelation curve was 26-times improved by heterodyne detection. Furthermore, the S/N ratio was improved by setting the sample cell at the sample grating distance where the electromagnetic field is maximum due to the Talbot effect. Size measurements for several kinds of nanoparticles were demonstrated by this new method.     

Determination of carbon in copper by photon activation analysis

Determination of carbon in copper has been studied by photon activation analysis using 30 MeV bremsstrahlung. Chemical separation of carbon as CO₂ was performed by the combustion method in a high flow rate of oxygen stream. It has been demonstrated that the trace amount of carbon in copper can be determined accurately and precisely, and that the detection limit is 0.02 g.     

Dimensional stability of regenerated cellulose film in relation to orientations of crystalline and noncrystalline phases

The dimensional stability of regenerated cellulose film on swelling with water is discussed in relation to the biaxial orientation of the two kinds of structural units, cellulose II crystallites and noncrystalline chain segments, and their anisotropic swelling (anisotropic absorption of water). Considerable dimensional stability in the plane of the film but enormous instability of thickness on swelling in water of some commercial cellophanes is qualitatively interpreted in terms of the planar orientation of crystal (101) planes along the film surface and the orientation of the noncrystalline chain segments parallel to the film surface. The dimensional changes on swelling from the completely dry state to 10% moisture regain were further interpreted quantitatively in terms of the degrees of biaxial orientation of the two kinds of structural units and their degrees of anisotropic swelling by modifying the Hermans monophase model for crystalline and noncrystalline biphase structures. The following degrees of anisotropic swelling of the structural units were thus obtained: q_{c, [101]} = 0.40%, q_{c, [101 ]} = ?0.33%, and q_a = 2.42%.     

Electrolytic determination of nanomolar concentrations of silver in solution with a piezoelectric quartz crystal

Silver in solution is determined in situ by the frequency change of a piezoelectric quartz crystal on electrodeposition on the electrode of the crystal. The electrolyte solution flows through a cell containing the platinum-plated electrode (cathode) of the quartz crystal, a coiled platinum-wire anode and a silver—silver(I) chloride reference electrode, and is electrolyzed at —0.2 V vs. $\text{Ag}\text{AgCl}$. The frequency change is proportional to the silver concentration in the range 10^-5–5 × 10^-7 M after electrodeposition for 5 min, and in the range 10^-8–10^-9 M by recycling 20 ml of the solution over the electrodes for 3 h.     

Measurement of the g-factor of the 0.57 ms 7+ state in202Tl

The spin rotation of the 0.57 ms 7⁺state in²⁰²Tl has been observed by use of a pulsed magnetic field and the g-factor was determined to be 0.128 ± 0.006. The isomeric state was excited via the ²⁰⁴Hg(p, 3n)²⁰²Tl reaction with a 28 MeV pulsed beam of 1.2 ms interval. From the results, the main configuration of the 7⁺ state in²⁰²Tl is interpreted as ().     

Application of modified normal pulse polarography and its differential mode to alkaline-earth metal ions in acid solutions

The simultaneous determination of alkaline-earth metal ions in acid solution was studied by modified normal pulse polarography. Well-defined waves were recorded for calcium, strontium and barium, but no limiting current was found for magnesium, because of its very negative reduction potential. The differential mode of this method gives peak-type polarograms and is useful for the simultaneous determination of species for which the half-wave potentials lie close together. The interference of dissolved oxygen was eliminated by the use of tetramethylammonium chloride as a supporting electrolyte.     

The binding energy of the deeply bound 0g92 hole coupled to active protons in the same shell

The binding energy of the $\text{0}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ hole state observed in neutron pick-up reactions is calculated in the framework of the shell model. Isospin symmetry and coupling between the hole and active protons in the same shell are taken into account.