Serotonergic modulation of spinal ascending activity and sacral reflex activity evoked by pelvic nerve stimulation in cats

Serotonin (5-HT) may be inhibitory to micturition at a spinal level. A potential mechanism of action for serotonergic inhibition of bladder function is a depression of the ascending limb of the supraspinal reflex mediating micturition. Ascending activity evoked by pelvic nerve stimulation was recorded in the thoracic spinal cord of anesthetized cats. For comparison, spinal reflex activity evoked by pelvic nerve stimulation was recorded on the pudendal nerve. The effects of intrathecal administration of serotonergic agents were examined to determine whether spinal and supraspinal responses to bladder afferent activation were modulated by 5-HT. Methysergide (60 nmol), a non-selective serotonergic antagonist, increased ascending activity by 61±7% and depressed spinal reflex activity by 38±6%. Zatosetron (10 nmol), a 5-HT₃ antagonist had a similar effect on both activities (increased by 93±24% and decreased by 77±7%, respectively). The effect on ascending activity of blocking 5-HT₃ receptors was also confirmed with ICS 205930 and MDL 72222. 2-Methyl-5-HT (800 nmol), a 5-HT₃ agonist, depressed ascending activity to 46±9% of control, but enhanced spinal reflex activity by 73±92%. These results demonstrate that stimulation of 5-HT₃ and methysergide-sensitive 5-HT receptors can inhibit ascending activity and facilitate spinal reflex activity elicited by activation of bladder afferents. It is suggested that descending serotonergic pathways may participate in the spinal coordination of urinary continence.     

IUD对子宫收缩的影响观察

本文重点研究妇女正常月经净后七天之内子宫收缩压力和频率,以及频脱器妇女与第一次置器妇女子宫收缩压及其相互间的差别。结果:(1)23例妇女月经净后七天之内子宫收缩压力为2.21～14.14mmHg/次,均值7.66±2.89mmHg/次。10分钟内子宫收缩28～76次,均值4.51±1.14次/分;(2)第一次置器妇女与频脱器妇女其置器前、后子宫收缩压力大小无显著差异(P>0.05)(3)子宫腔内有器子宫收缩压力比子宫腔内无器时大。两组子宫收缩压力t 检验结果(P<0.05)有显著差异:(4)第一次置(取)器前、后当时子宫收缩压力及频率大小皆有显著差异(P<0.05)。置(取)器后子宫收缩压力比置(取)器前大;(5)频脱组在置器前、后当时子宫收缩压力大小有显著差异(P<0.05),与第一次置器组相同;(6)本法测试子宫收缩压力达37～62mmHg/次时,部分受术者即有明显的下腹痛或痛感较强。     

输送链的结构与齿形探讨(三)——修正齿形链传动特性及完善齿形修正设计

本文讨论用“包络一轨迹”法设计的修正齿形链的传动特性,并提出了完善齿形修正设计的方法,基本上实现消除链传动申的“多边形效应”。     

Preparation and characterization of porous beta-tricalcium phosphate/collagen composites with an integrated structure

Porous beta-tricalcium phosphate (TCP)/collagen composites with different beta-TCP/collagen weight ratio were prepared. The influences of the preparation conditions on the microstructure of porous composite and the joint status of beta-TCP particles with collagen fibrils were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The results showed: (1) an acid treatment could effectively disassemble collagen fibrils; (2) in the resulting porous composites, beta-TCP particles homogenously existed on the skeleton of the collagen fibril network and bonded tightly to both the fibrils and themselves. The tight bonding formation could be due to the reaction between Ca ions in the particles and carboxyl groups in collagen polypeptide chains and due to the reprecipitation of partially dissolved beta-TCP during synthesis. The tight bonding between beta-TCP particles and collagen fibrils in the composites demonstrated an integrated structure, which was reproducible when beta-TCP/collagen ratio ranged from 2 to 4. Such integrated structure would make significant contributions in reliably tailoring properties of the porous composites by varying beta-TCP content. In addition, the porous composites had large porosity (approximately 95%) and appropriate pore size (approximately 100 microm), showed no negative impact in cytotoxicity assay and complete bone tissue regeneration after 12 weeks in animal test.     

Alpha-smooth muscle actin as a marker for soft tissue tumours: a comparison with desmin

The immunoreactivity of a range of vascular and non-vascular smooth muscle tumours, rhabdomyosarcomas, and non-myoid lesions has been examined with the use of a monoclonal antibody to smooth muscle-specific actin and the muscle intermediate filament, desmin. In all cases of smooth muscle-derived tumours, the alpha-actin antibody yielded superior results. Staining of the myofibroblasts of fibromatoses was also seen. In contrast to desmin, immunoreactivity was not exhibited by rhabdomyosarcomas. We propose that this monoclonal antibody to alpha-smooth muscle actin is a useful addition to the panel of reagents used for the characterization of soft tissue proliferations and tumours. The technical aspects of the application of this monoclonal antibody to immunohistochemistry are discussed.     

A novel active L1 retrotransposon subfamily in the mouse

Unlike human L1 retrotransposons, the 5' UTR of mouse L1 elements contains tandem repeats of approximately 200 bp in length called monomers. Multiple L1 subfamilies exist in the mouse which are distinguished by their monomer sequences. We previously described a young subfamily, called the T(F) subfamily, which contains approximately 1800 active elements among its 3000 full-length members. Here we characterize a novel subfamily of mouse L1 elements, G(F), which has unique monomer sequence and unusual patterns of monomer organization. A majority of these G(F) elements also have a unique length polymorphism in ORF1. Polymorphism analysis of G(F) elements in various mouse subspecies and laboratory strains revealed that, like T(F), the G(F) subfamily is young and expanding. About 1500 full-length G(F) elements exist in the diploid mouse genome and, based on the results of a cell culture assay, approximately 400 G(F) elements are potentially capable of retrotransposition. We also tested 14 A-type subfamily elements in the assay and estimate that about 900 active A elements may be present in the mouse genome. Thus, it is now known that there are three large active subfamilies of mouse L1s; T(F), A, and G(F), and that in total approximately 3000 full-length elements are potentially capable of active retrotransposition. This number is in great excess to the number of L1 elements thought to be active in the human genome.     

酵母双杂合系统AD端阴离子交换蛋白C-末端表达质粒的构建

利用PCR方法，从阴离子交换蛋白1（AE1）全长cDNA中扩增出约350bp c末端cDNA片段，测序后将其克隆至pGADT7载体上，用醋酸锂法构建好的pADT7-AE1-c末端转染酵母菌HA109，观察其在选择性培养基上的表达情况。结果表明，获得了530bp AE1c－末端cDNA,pGADT7-AE1-c末端对酵母无毒性，不能激活检测基因，可作为酵母双杂合系统中的靶基因。     

The relationship between muscle kinetic parameters and kinematic variables in a complex movement

Summary Kinematic variables of the vertical jump (jumping height, jump phase durations and joint angles) were measured on 39 male physical education students. In addition, kinetic parameters of the hip and knee extensors, and of the plantar flexors (maxima voluntary force and its rate of development) were recorded on the same subjects, in isometric conditions. The results demonstrated significant positive correlations between kinetic parameters of the active muscle groups and jumping height (r=0.217−0.464). The dominant effect on these correlations was due to the knee extensors. Correlations between these parameters and the duration of the jump phases were much weaker. Correlation coefficients between kinetic parameters and limb angles in the lowest body position showed that fast force production in one muscle group was related to a significant decrease in the joint angles of distant body segments. Multiple correlation coefficients between leg extensor parameters and kinematic variables (ranging between 0.256 for the duration of the counter-movement phase and 0.616 for jump height) suggested that kinetic parameters could explain more than a quarter of the variability of this complex human movement. Therefore, the conclusion was drawn that an extended set of measurements of the relevant musculo-skeletal system parameters could predict a considerable amount of the variability of human movement. However, high correlation coefficients between the same kinetic parameters of different muscle groups suggest that not all active muscle groups have to be included in the measurements.     

Muscle-specific expression of the smyd1 gene is controlled by its 5.3-kb promoter and 5'-flanking sequence in zebrafish embryos.

Zebrafish SmyD1 is a SET and MYND domain-containing protein that plays an important role in myofiber maturation and muscle contraction. SmyD1 is required for myofibril organization and sarcomere assembly during myofiber maturation. Whole-mount in situ hybridization revealed that smyd1 mRNAs are specifically expressed in skeletal and cardiac muscles in zebrafish embryos. However, it is unknown if smyd1 is expressed in other striated muscles, such as cranial and fin muscles, and moreover, the regulatory elements required for its muscle-specific expression. We report here the analyses of smyd1 expression using smyd1-gfp transgenic zebrafish. smyd1-gfp transgenic zebrafish were generated using the 5.3-kb smyd1 promoter and its 5'-flanking sequence. GFP expression was found in the skeletal and cardiac muscles of smyd1-gfp transgenic embryos. GFP expression appeared stronger in slow muscles than fast muscles in transgenic zebrafish larvae. In addition, GFP expression was also detected in cranial and fin muscles of smyd1-gfp transgenic zebrafish larvae. In situ hybridization confirmed smyd1 mRNA expression in these tissues, suggesting that the expression of the smyd1-gfp transgene recapitulated that of the endogenous smyd1 gene. Deletion analysis revealed that the 0.5-kb sequence in the proximal promoter of smyd1 was essential for its muscle specificity. Together, these data indicate that smyd1 is specifically expressed in most, if not all, striated muscles, and the muscle specificity is controlled by the 5.3-kb promoter and flanking sequences.