Biochemical Study on the Critical Period for Treatment of the Mottled Brindled Mouse

Hemizygous mottled brindled mice (Mobr/y mice) were treated by subcutaneous injection of copper and were decapitated on postnatal day 14. Cytochrome c oxidase (COX) activity of the brain mitochondria in the mice given 10 micrograms of copper/g on day 4 or 7 showed significant increases compared with that of untreated Mobr/y animals, and these mice had no neurological symptoms. Mice given 10 micrograms of copper/g on day 12 showed neither increases in COX activity nor clinical improvement. The brain levels of copper, noradrenaline, and dopamine in the mice treated on day 12 were the same as those in animals treated on day 4 or 7. The in vitro activities of dopamine-beta-hydroxylase of the brain were also the same among the treated mice, irrespective of the date of treatment. The results indicate that delays in copper treatment produce irreversible changes in COX activity of the brain and lead to clinical unresponsiveness to treatment.     

Increased Solubility of High-Molecular-Mass Neurofilament Subunit by Suppression of Dephosphorylation: Its Relation to Axonal Transport

Abstract: To investigate the role of phosphorylation in the turnover and transport of neurofilament (NF) proteins in vivo, we studied their solubility properties and axonal transport in the rat sciatic nerve using phosphatase inhibitors to minimize dephosphorylation during preparation. About 20% of the 200-kDa subunit (NF-H) in the axon was soluble in the 1% Triton-containing buffer under the present conditions, whereas this amount was less and more variable in the absence of phosphatase inhibitors. The 68-kDa subunit (NF-L) was exclusively insoluble and not affected by the inhibitors. Such selective solubilization of NF-H by phosphorylation differed significantly from the in vitro phosphorylation with cyclic AMP-dependent protein kinase, which resulted in NF disassembly. The carboxy-terminal phosphorylation state of NF-H probed with the phosphorylation-sensitive antibodies was also not directly related to solubility. The solubility of NF-H did not differ along the nerve. In contrast, the solubility of l -[³⁵S]methionine-labeled, transported NF-H was lowest at the peak of radioactivity. Higher solubility at the leading edge, regardless of its location along the nerve, indicates that NF-H solubility is positively correlated with the rate of NF transport.     

High rate of endoreduplications and chromosomal aberrations in hamster cells treated with sodium nitrite in vitro

As shown by results in this paper, NaNO2 induced endoreduplications and chromosomal aberrations as well as malignant transformation, in hamster cells in vitro, although the carcinogenic action of NaNO2 has not been reported in animals. The mode of action of NaNO2 in mammalian cells requires further investigation.     

Deoxyribonucleoside-3',5'-cyclic silanediyl derivatives: formation and properties

Formation of 3',5'-O-(dialkylsilanediyl)deoxyribonucleosides was studied. Treatment of deoxythymidine in DMF with bifunctional silylating reagent such as di-t-butyldichlorosilane and diisopropyldichlorosilane in the presence of imidazole gave the expected silanediyl derivatives. The structure was confirmed mainly by NMR spectroscopy. The stability of these cyclic silyl derivatives toward hydrolysis is also described.     

Preparation and Properties of Human Kappa-casein-like Fraction

A κ-casein-like fraction was prepared from human whole casein by gel filtration with Sephadex G-150 and Biogel A-150 m. The fraction was calcium-insensitive and its solution became turbid by rennin. In polyacrylamide gel electrophoretic (PAE) analysis, the fraction gave 11~12 bands after reduction with 2-mercaptoethanol. It appeared to exist as a disulfide- bound complex of many components. The occurrence of human para-IC-caseins from the fraction after rennin treatment was confirmed by PAE. When the reduced, alkylated human κ-casein-like fraction was chromatographed by DEAE-cellulose, several fractions were obtained. After rennin treatment, they formed either a para-SCM-κ-casein band moving toward the cathode on PAE pattern or the one which moved toward the anode. These results suggest that two para-κ-caseins were formed from human whole casein or human κ-casein-like fraction by the action of rennin.