Evidence for the participation of the proteasome and calpain in early phases of muscle cell differentiation

Objectives were to investigate the role of the proteasome and m-calpain to muscle cell differentiation. Accordingly, we investigated the effects of lactacystin, a proteasome inhibitor, and calpain inhibitor-II (CI-II) on L8 muscle cell differentiation and assessed concentrations of proteasomal and calpain subunit mRNAs during differentiation. L8 myoblasts were induced to differentiate by culturing in mitogen-depleted medium. To assess the importance of the proteasome and calpain to differentiation, we examined effects of lactacystin and CI-II on creatine kinase (CK) activity. In the absence of inhibitor, CK activity was detectable within 48 h of mitogen depletion and myotubes were formed. Addition of lactacystin or CI-II to cultures drastically reduced CK activity and prevented formation of myotubes. Hence, proteasome and calpain are both necessary for differentiation. In order to identify which proteasomal subunits were regulated during differentiation, we examined the concentrations of two 20S core subunits (C8 and C9) and three 22S ATPases (MSS1, S4 and TBP1) during differentiation. Concentrations of m-calpain and beta-tubulin mRNAs were also assessed. Differentiation was associated with slight increases (ca. 30%) in concentrations of mRNAs encoding the proteasomal 20S core subunits (C8 and C9) and with large increases (approximately 2-fold) in mRNAs encoding the regulatory subunit ATPases. m-calpain mRNA concentration also increased two-fold following mitogen depletion. beta-Tubulin mRNA concentration remained unchanged early in the differentiation process and thereafter declined. Of interest, changes in proteasomal and m-calpain mRNAs occurred within 6-24 h of mitogen depletion (i.e., at least 24-36 h prior to detectable changes in creatine kinase activity). These results indicate that changes in expression of proteasome and calpains subunits occur early in the differentiation process. These changes may be required for the normal course of differentiation to proceed. Differentiation is associated with larger changes in proteasomal ATPase mRNAs than in 20S core particle mRNAs indicating that either turnover rates of the 22S ATPase subunits are more rapid in differentiating cells than of the 20S core particles or that functions of the regulatory subunits become more important during muscle cell differentiation.     

稠油斜直井有杆泵抽油技术

介绍了我国第一组稠油料直井应用有杆泵抽油的情况,通过游梁式抽油机抽油泵装置满足稠油热采不动管柱注汽和采油的要求。介绍了斜直井稠油热采有杆泵抽油配套工具的性能和特点,对斜直井的主要技术难点──外直井抽油杆扶正器的间距和斜直井抽油机悬点负荷进行了分析和计算,最后总结了斜直井有杆泵抽油方式的特点。     

Pharmacokinetics of a single dose of phenylpropanolamine following oral administration at two different times of the day

Pharmacokinetics of a single oral dose of phenylpropanolamine (CAS 154-41-6) was investigated by administering 50 mg of the drug at 10.00 and 22.00 h to 8 healthy male volunteers in a crossover design with a wash-out period of 10 days. Serum samples were analysed for phenylpropanolamine using high performance liquid chromatography. Pharmacokinetic parameters were calculated using model independent method. A significant (p < 0.05) elevation in Cmax (227.45 versus 181.98 micrograms/l) was observed following the drug administration at 22.00 h as compared to 10.00 h. These variations may be due to circadian changes in gastric pH contributing to the time dependent changes in the absorption of the drug.     

宽带高频放大器SA5204A的原理及应用

介绍宽带高频放大器SA5204A的基于多反馈环路设计的工作原理,结合宽带高频功率放大器的特点,从“S”参数最大/最小限制定义功率增益,分析通常在信号源阻抗或负载阻抗与高频放大器网络匹配情况下的增益特性和影响功耗的基本因素。使用推荐的参数得到很好的频率响应特性和噪声抑制。实验证明,在正常工作状态下,验证其宽带高频放大功能的正确性和实用性。     

Cell cycle control of chorion gene amplification

Over-replication of two clusters of chorion genes in Drosophila ovarian follicle cells is essential for rapid eggshell biosynthesis. The relationship of this amplification to the follicle cell cycles has remained unclear. To investigate the regulation of amplification, we developed a technique to detect amplifying chorion genes in individual follicle cells using BrdU incorporation and FISH. Amplification occurs in two developmental phases. One of the gene clusters begins to amplify periodically during S phases of follicle cell endocycles. Subsequently, after endocycles have ceased, both clusters amplify continuously during the remainder of oogenesis. In contrast to the early phase, late amplification commences synchronously among follicle cells. The pattern of Cyclin E expression mirrors these two phases. We present evidence that Cyclin E is required positively for amplification. We suggest that Cyclin E also acts negatively to inhibit refiring of most origins within a cycle, and that specific factors at chorion origins allow them to escape this negative rereplication control. Our findings suggest that chorion amplification is a model for understanding metazoan replicons and the controls that restrict replication to once per cell cycle.     

Targeted transduction of CD34+ cells by transdominant negative Rev-expressing retrovirus yields partial anti-HIV protection of progeny macrophages

Congenitally acquired HIV infection may be uniquely suited to treatment via genetic engineering of CD34+ hematopoietic stem/progenitor cells. However, current technologies yield only a small percentage of mature cells that carry the inserted genes, and expression is frequently suppressed. Since clinical trials employing these methodologies have been proposed for anti-HIV gene therapy of HIV-infected children, we wished to assess, by in vitro modeling, the expected limits of transduction efficiency, expression, and antiviral activity using currently available methods. We measured retrovirus-mediated transduction in cord blood progenitors and their in vitro-derived progeny macrophages by Mo-MuLV vectors expressing a transdominant negative Rev (RevTD). CFU-GM transduction efficiency ranged from 7 to 85%, with an average of 28%. Semiquantitative DNA PCR demonstrated < or =100 vector sequence copies per 1000 cells in monocyte/macrophage cultures, which were grown without selection to better model in vivo conditions. When challenged with the macrophagetropic HIV-1BaL isolate, cultured macrophages from mock-transduced CFU-GM colonies supported infection in eight of eight experimental cultures, control LXSN-transduced progenitors supported infection in six of eight cultures, while macrophages derived from RevTD-transduced CFU-GM colonies supported infection in four of eight cultures. Although these results support the ability of neo(r) retroviral vectors containing RevTD to inhibit HIV replication, they indicate that further optimization of transduction efficiency and sustained expression will be required for effective anti-HIV protection in vivo.     

Expression of MAGE genes in ocular melanoma during progression from primary to metastatic disease

Tasks which assess children's speaker skills in the referential communication paradigm frequently mark the target item in some way to indicate which picture should be described. It was hypothesized that this procedure would interfere with effective scanning of the visual array (comparison processing) assumed to be necessary for the production of accurate messages. It was also predicted that, when one item was highlighted, more redundant features would be included in messages. An experiment which compared a marked with an unmarked target condition across three age ranges (6, 8, 10 years) found that message accuracy was not affected by highlighting. But significantly more redundant features were reported in the marked condition, indicating that, where redundancy is the focus of interest, a highlighting procedure should be avoided. Two age effects were also found: Message accuracy improved with age, while redundancy reduced with age.     

Quality-of-life changes in patients with thyroid cancer after withdrawal of thyroid hormone therapy

Quality of life (QOL) is an important consideration as patients survive longer with cancer and is an area of increasing interest in patients with thyroid cancer who undergo long-term cancer surveillance. However, there are few disease-specific QOL tools available to evaluate QOL in patients with thyroid cancer. The purposes of this longitudinal, repeated-measures study were to: (1) test a new instrument, the QOL-Thyroid Scale, during thyroid hormone withdrawal; and (2) to evaluate the impact of thyroid hormone withdrawal on patients' perceived changes in quality of life. The sample included 34 subjects (mean age 40 years) undergoing thyroid hormone withdrawal in preparation for scanning procedures. Subjects completed three instruments (demographic data tool, the QOL-Thyroid, and the FACT-G) at four specific time points in relationship to scanning. The results demonstrated that the QOL-Thyroid tool is a reliable and valid measure of QOL. Cronbach's alpha coefficient of r = .78 between QOL-Thyroid and FACT-G indicated good concurrent validity. Second, the impact of thyroid hormone withdrawal on QOL showed significant changes in physical, psychological, and social well-being across the four testing points. The greatest changes occurred between peak hormone withdrawal and thyroxine (T4) therapy. While it is generally known that patients suffer troublesome physical symptoms relating to thyroid hormone withdrawal, the negative psychological, family, and work sequelae are less apparent. In conclusion, the QOL-Thyroid is a reliable and valid measure for use in evaluating patients undergoing scanning procedures and may be used to identify and target teaching and support for high-risk areas in patients lives that are negatively affected by hormone withdrawal.