人鼻咽癌细胞基因组中瘤基因Ha－ras－1的Dnase Ⅰ超敏感位点的初步研究

ＤＮａｓｅⅠ超敏感位点的研究能够发现潜在的调控基因转录活化的位点,比较正常人外周血有核细胞,淋巴瘤细胞株Ｐ３ＨＲ１和人鼻咽癌低分化磷癌细胞株ＨＯｎＥ１和ＨＮＥ２中Ｈａ－ｒａｓ－１瘤基因的ＤＮａｓｅⅠ超敏感位点发现,只有ＨＯＮＥ１和ＨＮＥ２细胞基因组中存在一个ＤＮａｓｅⅠ超敏感位点,位于第一个外显子上游０．３７ｋｂ处,上述结果提示正常白细胞和Ｐ３ＨＲ１细胞中Ｈａ－ｒａｓ－１基因处于失活状态,而在鼻咽癌细胞基因组中则处于活化状态,它的活化可能与０．３７ｋｂ处的ＤＮＡ序列有密切的关系。     

玉米根细胞中对钒酸盐敏感的H~＋－泵的研究

用奎吖咽（ｑｕｉｎａｃｒｉｎｅ）作荧光指标剂,测定玉米（ＺｅａｍａｙｓＬ．）根尖微粒体（ＭＩＣ）膜囊泡的Ｈ~＋－泵活性,结果表明１ｍｍｏｌ／ＬＮａＮ_３仅抑制该泵活性约８％,而０．８ｍｍｏｌ／Ｌ钒酸盐（Ｖａｎ）则可抑制其活性达８０％,说明ＭＩＣ制剂中Ｈ~＋－泵活性主要由质膜（ＰＭ）Ｈ~＋－ＡＴＰａｓｅ产生。此泵活性严格需要Ｍｇ~（２＋）,二价阳离子作用大小的顺序为Ｍｇ~（２＋）＞Ｍｎ~（２＋）＞Ｚｎ~（２＋）＞Ｃａ~（２＋）＝０;阴离子作用大小的１顺序为Ｂｒ~－＞Ｃｌ~－＞ＮＯ_３~－＞ＳＯ_４~（２－）,并初步证实当质膜同侧发生电子传递时,没有跨膜Ｈ~＋梯度（△μＨ~＋）生成。     

Effects of estradiol and testosterone on the synthesis,expression and degradation of androgen receptor in human uterine endometrial fibroblasts

The mechanism of known receptor-mediated androgen effects on the endometrial stroma was studied in endometrial fibroblasts derived from human uterus. 17-Estradiol (E) induced the expressions of androgen receptor (AR) mRNA, and predominantly increased the level of testosterone-binding sites (TBS) in uterine endometrial fibroblasts. The effect on the level of dihydrotestosterone-binding sites (DHTBS) was similar but smaller. This result suggests that the AR mRNA expressed might encode TBS, but probably not DHTBS. The TBS level increased by estrogen was down-regulated by testosterone (T) + E, but the AR mRNA expression increased by E was not down-regulated by E + T in the fibroblasts. Although the synthesis rate of AR was slightly increased (p<0.05) by E alone or E + T, the degradation rate of AR was significantly accelerated (p<0.05) by E + T in the fibroblasts. This result suggests that T might stimulate the metabolic rate of TBS, but does not inhibit the synthesis rate of AR mRNA to TBS in endometrial fibroblasts.     

Fate of Parasite and Host Organelle DNA during Cellular Transformation of Red Algae by Their Parasites

The transfer of a nucleus into a cytoplasm of a genetically foreign cell and its subsequent multiplication in the cytoplasm of this cell characterize most parasitic red algal species and their interactions with specific red algal hosts. Nuclei enter the host's cytoplasm upon cell fusion of parasite and host cell; here, they replicate, are spread to contiguous host cells, and ultimately are packaged into spores that reinfect other host thalli. In this study, we examined whether the proplastids and mitochondria that occur in these red algal adelphoparasites are acquired from their host or whether they are unique to the parasite and are brought into the host along with the parasite nucleus. To establish their origins and fates, plastid and mitochondrial restriction fragment length polymorphisms (RFLPs) of parasite cells were compared with those of their host plastid and mitochondrial DNA in three host and parasite pairs. For plastids, no RFLP differences were found between hosts and parasites, supporting an earlier conclusion, based on microscopic studies, that the proplastids of parasites are acquired from their hosts. For mitochondria, characteristic RFLP differences were detected between host and parasite for two of the pairs of species but not for the third. Evidence of the evolutionary difference between hosts and their parasites was shown by RFLP differences between nuclear ribosomal repeat regions.     

Isolation of Propionibacterium acnes from central nervous system infections

Propionibacterium acnes is a common skin colonizer and its involvement in central nervous system (CNS) infections may be related with previous neurosurgical procedures. P. acnes was isolated in pure or mixed cultures from ten patients with CNS infections during a 5-year period. The clinical presentation, treatment and outcome were retrospectively reviewed. Nine out of 11 patients had CNS infections after a neurosurgical procedure. The clinical presentation was: brain abscess (five patients), subdural or epidural empyema (four patients) and shunt meningitis (one patient). Three patients had also secondary meningitis. All patients received antibiotic therapy and all abscesses and empyemas were drained. The patient with shunt meningitis cured without catheter removal. Only one patient with a brain abscess by P. acnes died, but several months thereafter and as a consequence of a Gram-negative superinfection. P. acnes is a pathogen for the CNS and infections must be surgically managed under adequate antibiotic treatment.     

Comparison of arbitrarily primed polymerase chain reaction and ribotyping for subtyping Actinobacillus actinomycetemcomitans

This study investigated the compatibility of arbitrarily primed polymerase chain reaction (AP-PCR) and ribotyping in the characterization of Actinobacillus actinomycetemcomitans , a major pathogen in the mixed anaerobic microflora of human periodontitis. AP-PCR was performed directly on lysed bacterial colonies using a random-sequence 10-base oligonucleotide primer. Ribotyping was carried out by using purified bacterial chromosomal DNA digested with BglI. DNA fragments were separated electrophoretically, blotted onto a nylon membrane and hybridized with the plasmid pKK3535 containing the rRNA operon of Escherichia coli. The two genetic methods were evaluated on isolates from single individuals and from family members. Twelve AP-PCR types and 47 ribotypes were distinguished among 76 A. actinomycetemcomitans isolates of different serotypes. AP-PCR typing and ribotyping gave compatible results in 18 of 20 comparisons. Although AP-PCR detected less genetic heterogeneity in A. actinomycetemcomitans than ribotyping, the rapid and relatively simple AP-PCR technique seems to be sufficiently discriminative to be used in large scale epidemiological studies which preclude the application of the more laborious ribotyping technique.     

Lymphocyte movements and interactions in microgravity

Cell-cell contacts and the formation of aggregates play an important role in the mitogen induced in-vitro activation of lymphocytes. The fact that the formation of cell aggregates is only slightly reduced in microgravity suggests that cells are moving and interacting also in space. Direct evidence was obtained for the first time in an experiment performed on a sounding rocket flight, where the movements and interactions of free-floating, non activated cells could be observed in real time in microgravity. In an experiment performed on the IML-2 mission in July 1994, the movements and interactions of human lymphocytes during activation with the mitogen Con A were studied in real time in microgravity.     

Concept of new tool to simulate human physiological reactions in microgravity

This paper describes a new tool for weightlessness simulation--the Acceleration-Immersion Imitator of Sensation of Microgravity (AIISM), which aims to incorporate the otolithic input, the unloading of proprioceptors, and the fluid shifts that occur in microgravity. The facility is a kind of centrifuge chamber filled with water. The workings of the facility are described as well as the way the chamber simulates microgravity conditions.     

Comparison of voice stress reactivity under psychological stress test and simulated Mir docking manoeuvre

The relation between the results of laboratory tests and results of the interesting professional work is a very difficult one. The same is true for the relation between training and real performance. The pilot controlled MIR-docking manoeuvre is in reality a very seldom but very important one. The training of this manoeuvre is a very special professional work and only for cosmonauts available. But the objective estimation of the performance and the used objective and subjective needs is nevertheless necessary. Even for the subjective "stress"-feelings during task solving it is often impossible to get reliable data without any physiological measurements. The use of electrodes, cables and equipments is hardly limited during real work. Sometimes only the voice is available over more or less quality communication channels. So it is the case during the training and the real pilot controlled MIR-docking manoeuvre. Based on findings in the literature and own experiments analyzing the relation between fundamental voice frequency (F0) and subjective stress feelings we tested the hypothesis that a on-line measurement of F0 can be used for stress evaluation during standardised training sessions of MIR-docking manoeuvres.