碱性成纤维细胞生长因子促进神经损伤修复的研究进展

碱性成纤维细胞生长因子(basic fibroblast growth factor,b FGF)是成纤维细胞生长因子家族(FGFs)的成员之一。它是哺乳动物和人体中一种非常微量的活性物质,因其具有广泛的生理功能和重要的临床应用价值受到了国内外学者的高度重视。b FGF生物活性的多效性以及神经营养的广谱性,为其从基础走向临床提供了保证。而b FGF如何发挥神经损伤修复作用的功能和机制,仍有待进一步的发现及研究,这也是目前国内外探索和开发b FGF新临床药物的研究热点之一。针对b FGF的生物学特点及其在神经损伤修复中的功能,特别是在中枢神经系统和外周神经系统疾病中的研究进展进行了综述。     

Nucleocytoplasmic Incompatibility in Androgenetic Fish Hybrids Can Be Overcome

Many androgenetic fish hybrids are nonviable due to the disturbed interaction between the foreign nucleus and the cytoplasm. It has been proposed that this incompatibility can be overcome if eggs from interspecific hybrids and sperm from one of the parental species are used for diploid androgenesis. Indeed, the androgenetic progeny obtained as a result of the insemination of the enucleated eggs of goldfish and carp hybrids by the carp spermatozoa proved to be viable and fertile. This approach may be used for reconstitution of the genotypes of rare or disappearing fish species with the help of induced androgenesis, if their native or cryoconserved sperm is available.     

里氏木霉GXC木聚糖酶的研究*

研究了里氏木霉GXC产木聚糖酶的条件和酶学性质。结果表明,适宜产酶碳源为乳糖、甘露糖、棉子糖、木聚糖和麸皮,氮源为牛肉膏和酵母膏;产酶的最适初始pH为4.0,30℃培养60h。对以麸皮为碳源的培养液进行纯化的酶特性研究表明,木聚糖酶的最适反应温度为50℃,pH为5.5,该酶在pH5.0(7.0和40℃以下相对稳定。Fe3+和Mn2+对木聚糖酶有较大的促进作用,Cu～2+、Fe～2+和Ca～2+ 具有抑制作用。     

Detection of human papillomavirus gene sequences in cell lines derived from laryngeal tumors

The role of Human Papillomaviruses (HPV) in laryngeal carcinomas has been studied with conflicting results. To evaluate the etiologic relationship between HPV infection and epithelial malignancy of the larynx we studied five laryngeal carcinoma cell lines obtained from patients undergoing surgery for laryngeal tumors. The paraffin embedded biopsy samples of the original tumor and different passages of the new established cell lines were investigated by PCR with consensus primers specific for HPV DNA. The findings indicate that HPV infection is associated with some larynx carcinomas. The positive association has been enhanced when a method of enrichment of epithelial cells from fresh tumor samples was used. All tumor cells enriched smears were positive for HPV DNA not only by PCR but also by in situ hybridization (ISH). Investigated by PCR, different passages of larynx tumor cell lines maintained expression of HPV DNA. At subsequent passages ISH gives constantly no signals suggesting a minimal amount of viral harbored sequences. In one cell line propagated more than 60 population doublings, the chromosomal frequency distribution shifted from modal number 46 at the 5^th passage to 63 at the 60^th passage. The mechanisms by which persistent HPV infection maintains continuous cell proliferation were discussed.     

A mechanism and an evaluation of surface specific iodination by the chloramine-T procedure.

Both internal and external proteins in vesicular stomatitis virus were labeled when intact virions were iodinated with 50 μm iodide; however, only the surface proteins were labeled when the same procedure was carried out at low iodide concentrations (below 0.5 μm). This result together with similar observations reported earlier with another enveloped virus, Rous-associated virus-61 (RAV-61), suggest that viral envelopes provide a barrier to iodination by chloramine-T at low, but not at high, iodide concentrations. By monitoring the permeability of the RAV-61 envelope to successive iodinations and to iodination in the presence of chaotropic thiocyanate ions, it was shown that the permeability of the viral envelope was not altered at the higher concentrations of iodide. Further results support the hypothesis that iodination mediated by chloramine-T inolves two different iodinating species: (a) a membrane impermeable one, possibly “iodamine-T,” which predominates at low iodide concentrations, and (b) a membrane permeable species, possibly molecular iodine, which predominates at high concentrations of iodide. These results reinforce the proposal that the chloramine-T procedure is a useful method for specifically labeling surface proteins of lipid-enveloped structures.     

Lordosis: Inhibiting effects of progesterone in the female rat

Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented.     

Early Stimulation of Phosphatidylcholine Biosynthesis During Wallerian Degeneration of Rat Sciatic Nerve

Phospholipid metabolism was studied in rat sciatic nerve during Wallerian degeneration induced by crush injury. Portions of crushed sciatic nerve, incubated with labeled substrates, showed significantly higher phosphatidylcholine synthesis than normal nerve, prior to any measurable alterations of phospholipid composition. Maximum synthesis occurred 3 days after crush injury, at which time the metabolism of other phospholipids was unchanged. After a rapid decrease in biosynthetic activity, a second phase of enhanced phosphatidylcholine synthesis occurred, beginning 6 days after crush injury. Increased incorporation of [33P]phosphate, [2-3H]glycerol, and [Me-14C]choline indicated stimulation of de novo synthesis of phosphatidylcholine 3 days after injury. Neither base exchange reactions nor sequential methylation of ethanolamine phospholipids contributed significantly to phosphatidylcholine synthesis. Assay of certain key enzymes under optimal conditions in subcellular fractions of sciatic nerve revealed higher activities of cholinephosphate cytidyltransferase, choline phosphotransferase, and acyl-CoA:lysophosphatidylcholine acyltransferase in injured nerve, while choline kinase activity remained unchanged. This indicates that stimulation of phosphatidylcholine synthesis occurs via the cytidine nucleotide pathway, as well as by increased acylation of lysophosphatidylcholine. Although the cause of stimulated phosphatidylcholine synthesis remains unexplained, it is possible that trace amounts of lysophospholipids or other metabolites produced by injury-enhanced phospholipase activity may be responsible.     

Modification of the C-terminal octapeptide of cholecystokinin with a high-specific-activity iodinated imidoester: preparation, characterization, and binding to isolated pancreatic acinar cells

Proteoglycans were separated by high-performance liquid chromatography (HPLC), using two coupled Aquapore columns containing glycerylpropylsilane groups covalently linked to large-pore (50–100 nm) silica spheres. This two-column HPLC system was effective in separating cartilage proteoglycan aggregates and monomers, without altering their biochemical integrity. This system was also effective in resolving small amounts of isotopically labeled proteoglycans synthesized by cultured mammalian cells. The small sample size, short analysis time, and high reproducibility represent improvements in the study of proteoglycans over conventional soft-gel chromatography.     

The occurrence of the second moult of Ascaris lumbricoides and Ascaris suum

Maung M. 1978. The occurrence of the second moult of Ascaris lumbricoides and Ascaris suum. International Journal for Parasitology 8: 371–378. Eggs of Ascaris lumbricoides and A. suum were cultured at 28°C and observed daily. Larvae were released by pressure, by artificial hatching with CO₂, and by natural hatching after infection of laboratory mice. The early stages of development in the egg were observed to comprise two moults, one occurring immediately after the other. Both moults were initiated within the egg, but the time of completion of the second moult varied considerably, and in some instances was not completed until the larvae reached the liver of experimentally infected animals.