Sur la stéréospécificité de la ribonucléoside-diphosphate-réductase: préparation de désoxyribonucléosides pyrimidiques deutérés

Methyl 2-deoxy-3,5,6-tri-O-p-nitrobenzoyl- -ribo-hexofuranoside was converted into the glycosyl halide which was then condensed with 2,4-bis(trimethylsilyloxy)-pyrimidine in the presence of mercuric chloride to give, after alkaline methanolysis, 1-(2-deoxy-β- -ribo-hexofuranosyl)uracil, in a yield too low for the reaction to be applied to deuterated compounds. Methyl 2-deoxy- -allofuranoside-2-d was degraded into methyl 2-deoxy- -arabinofuranoside-2-d. Its di-p-nitrobenzoate was converted into the glycosyl halide which was coupled with 2,4-bis(trimethylsilyloxy)-pyrimidine to give, after alkaline hydrolysis, deuterated deoxyuridine. Thiationammonolysis of a mixture of the 3′,5′-di-p-nitrobenzoates of the latter compound and its anomer gave the corresponding deoxycytidines. Comparison of the n.m.r. spectra of these compounds to that of deuterated deoxycytidine, prepared by the enzymic reduction of cytidine 5′-pyrophosphate with the Escherichia coli system in the presence of deuterium oxide confirmed that the substitution of a hydroxyl group by a hydrogen atom proceeds with retention of configuration.     

Changes in retinal aquaporin-9 (AQP9) expression in glaucoma

The eye contains numerous water channel proteins and the roles of AQPs (aquaporins) in the retina are blurred, especially under disease conditions. The purpose of this study was to investigate the expression of AQP9 gene and proteins affected by elevated IOP (intraocular pressure) in a rat model of glaucoma induced by intravitreous injection of hypertonic saline into the episcleral veins. The gene and protein expressions of AQP9 were investigated by real-time PCR and Western blotting. The immunoreactive expression of AQP9, AQP4 and GFAP (glial fibrillary acidic protein) in the optic nerve of rats exposed to experimentally elevated IOP was detected by immunofluorescence microscopy. The mRNA and protein expression levels of AQP9 were up-regulated in the retina of an animal model of glaucoma. The immunoreactivities of the AQP9, AQP4 and GFAP were also detected and increased in the optic nerve region. The expression of AQP9 was up-regulated in this glaucoma model and the immunoreactivities of the AQP4 and GFAP were also detected as co-localizing with AQP9 in the optic nerve region, indicating retina ganglion cells were surrounded by activated astrocytes. This may indicate that the injured neurons may rely on the astrocytes. The alterations of AQP expression may compensate the glaucomatous damage.     

Amino-acids condensations in the preparation of N alpha-9-fluorenylmethyloxycarbonylamino-acids with 9-fluorenylmethylchloroformate

Synthesis of N alpha-9-fluorenylmethyloxycarbonyl (Fmoc) amino-acids by reaction of free amino-acids (glycine and alanine) with 9-fluorenylmethylchloroformate leads to formation of small amounts of Fmoc-dipeptide which are difficult to eliminate by crystallization. The alternative way to prepare Fmoc-amino-acids by reacting the Fmoc-chloride first with sodium azide and then with the free amino-acid eliminates this side reaction, at least for glycine and alanine.     

Étude du mécanisme d'établissement des liaisons glutaraldéhyde-protéines

Commercial aqueous 25 per cent glutaraldehyde solutions contain no stable derivative of this aldehyde, but compounds of variable molecular weight which easily revert to glutaraldehyde. The effect of pH on the reaction of glutaraldehyde with amino acids and on the stability of the products under acid conditions, shows the importance of the structure modification of the dialdehyde which occurs when pH increases, and even leads to precipitation in highly alkaline solutions. This precipitate results from aldol condensation of glutaraldehyde molecules. It contains aldehyd groups conjugated with ethylenic double bonds. Such a structure reacts with amino groups to give an imino bond, stabilized by resonance with the ethylenic bond, and does not undergo Michael-type addition reactions.Therefore, glutaraldehyde does not react with proteins under its free form, but as an unsaturated polymer, which gives imino bonds stabilized by conjugation.     

Solubilisation et caractérisation d'une glycoprotéine : fucosyl-transférase cérébrale

1. A glycoprotein: fucosyl-transferase activity was demonstrated in sheep cerebral cortex, using desialylated fetuin as exogenous acceptor and detergent Trition X 100 for solubilization.

2. Addition of Triton X 100 to the membrane suspension gave first an activation then a solubilization of the cerebral fucosyl-transferase.

3. Hydrophobic chromatography was investigated for purification of the enzyme. Binding was effective using alkyl-agarose chromatographic columns with two or more than two atoms of carbon, but elution was only possible with ethyl and butyl-agarose.

4. Combination of subcellular fractionation and hydrophobic chromatography on ethylagarose led to a 30 fold purification.

5. After ethyl-agarose chromatography, some properties of fucosyl-transferase were studied: the optimal temperature was 25°C. The optimum pH was about neutrality. Light activation was observed with Mn²⁺ concentration below 1 mM.

6. Homogeneity was tested using Ultrogel chromatography, polyacrylamide gel electrophoresis and ultracentrifugation.

7. It was concluded that ethyl-agarose hydrophobic chromatography easily bind a few solubilized proteins (about 20 per cent of the ST supernatant). When elution was performed, these proteins, including fucosyl-transferase, were released from ethyl-agarose columns as a stable aggregate, only dissociated with lower ionic strength.

Ethyl-agarose fraction (eluted with KCl 120 mM) showed homogeneity:

— with Ultrogel AcA 22 chromatography (Mw = 300.000).

— with polyacrylamide gel electrophoresis without S.D.S.

— with the analytical ultracentrifugo giving Mw = 280.000; S₂₀ = 10.

But after dialysis overnight against a buffer without KCl, ultracentrifugation technics showed no homogeneity. Futhermore, SDS gel electrophoresis gave more than four bands.     

Trisomy 9p with an isochromosome of 9p

An 18 1/2-year-old female is described with moderately severe mental retardation, the phenotype of the trisomy 9p syndromy, and an isochromosome for the short arm of a chromosome 9, contained in an unique karyotype, 46,XX,-9,t(7q9q),+ iso 9p.     

Trisomy 9p with an isochromosome of 9p

Summary An improved technique for cultivation of peripheral human lymphocytes is presented. The settling of the blood cells is replaced by a wash in Ficoll to remove the polymorphonucleocytes.     

抗H9亚型流感病毒HA抗血清对小鼠的被动免疫预防和治疗研究

H9亚型流感病毒是引起大流感的潜在威胁.抗血清被动免疫是一种有效的应对流感的方法.采用H9N2禽流感病毒血凝素(hemagglutinin,HA)DNA重组质粒免疫BALB/c小鼠制备抗血清.在致死量同源病毒感染前或后通过尾静脉给小鼠注射不同剂量抗血清,观察小鼠14d内的体重丢失率和死亡率.结果显示,1280血凝抑制单位(hemagglutination Inhibition unit,HIU)抗血清可给小鼠提供至少长达11d的100%预防和1d的80%治疗保护.HA DNA疫苗免疫制备的抗血清可以有效地抵抗同源H9病毒的致死攻击,在H9病毒感染的预防和治疗中发挥作用.     

In search of a 9q13 latent centromere in 9qh polymorphic inversions

In search of a 9q13 latent centromere in 9qh polymorphic inversions: The presence of alphoid sequences in 9q13 has prompted the suggestion that such a region could harbor a latent centromere which under certain circumstances may appear as a neocentromere. We tested this hypothesis by means of FISH with a centromere 9-specific alphoid probe in lymphocyte metaphases from 13 unrelated individuals with a 9qh polymorphic inversion. Since all inverted chromosomes had the alphoid signal onto the primary constriction, it was not possible to identify any neocentromere . We believe, however, that the number of cases was not enough to conclude that all the polymorphic inversions of chromosome 9 are genuine.