A possible role of initial cell death due to mechanical stretch in the regulation of subsequent cell proliferation in experimental vein grafts

 The proliferation of vascular cells contributes to the formation of neointima and hypertrophy of the blood vessel wall. Here we show that mechanical stretch possibly regulates the proliferation of vascular cells via the mediation of cell death in a rat vein graft model. The wall of vein grafts is subject to a suddenly increased mechanical stretch due to exposure to arterial blood pressure. Such a stretch induces rapid cell death with a reduction in cell density by ∼60% within the first day after surgery. The initial cell death was followed by an increase in the percentage of proliferating cells, as shown by a BrdU incorporation assay (1.55 ± 1.27%, 8.48 ± 2.27%, 11.93 ± 2.36%, 6.36 ± 1.77%, and 5.60 ± 1.46% at days 1, 5, 10, 20, and 30, respectively). When mechanical stretch was reduced by restraining the vein graft using a polytetrafluoroethylene sheath, the percentage of proliferating cells reduced significantly (0.76 ± 0.76%, 1.70 ± 0.46%, 1.29 ± 0.56%, 0.99 ± 0.83%, and 0.47±0.52% at days 1, 5, 10, 20, and 30, respectively). A further reduction in cell density, induced by local administration of a cell death inducer ceramide to experimental vein grafts (without sheath), enhanced subsequent cell proliferation. In contrast, a prevention of cell death, induced by local administration of a cell death inhibitor tetrapeptide-aldehyde DEVD-CHO to experimental vein grafts (without sheath), significantly reduced subsequent cell proliferation. These results suggest that mechanical stretch induces cell death, which possibly mediates subsequent cell proliferation in the present model. Received: 9 September 2001 / Accepted: 19 November 2001     

Several morphologic changes in the blood vessels of the rabbit medulla oblongata arising under the influence successive exposure to gravitational overloading and hypokinesia]

Morphological changes in blood vessels of the rabbit medulla oblongata were studied after successive effects of maximum-bearing gravitational overloadings of 10 units applied at different directions and hypokinesia of various duration. Blood system of 35 rabbits was injected with Gerota's mass, cleared horizontal sections of the medulla oblongata 120 mkm thick were stained with hematoxylin--eosin and after Van Gieson. The experiments demonstrated various, quantitative and qualitative, changes in the vessel structure of the medulla oblongata, prevalence of one of the factors applied--in one combination and successive application; total resulting effect of overloading and hypokinesia--in the other combination; peculiar morphological changes unusual to any of the two factors--in the third combination. It was also demonstrated that readaptation for 12 weeks resulted in a significant restoration of the blood vessel structure in the rabbit brains preliminarily subjected to a successive effect of hypokinesia for 4 weeks and overloading in cranio-caudal directions.     

Mechanisms of vascular adaptation to long-term orthostatic gravitational loading

Frequent symptoms and serious complaints related to orthostatic intolerance are among the important reasons for investigating the long-term control mechanisms of blood vessels especially those of veins. Previously we studied perfused and superfused saphenous vein segments from rats maintained in head-up tilt position for two weeks. It was found that passive lumen capacity and acute pressure induced myogenic response of these vessels increased substantially without measurable change in wall thickness. Sympathetic component of the smooth muscle cell membrane potential determined in vivo was also significantly enhanced in this vein, but no such change was seen in the saphenous artery and in the brachial vessels. In a separate study, rarefaction of microvessels was found in the hind limb oxydative muscles after two-week tilting, while muscular water content was unaltered. These results suggest that long-term gravitational loading may induce adaptive rearrangement of the blood vessel functions. The aim of the present study was to quantitate and compare the density of nerve fiber terminals as well as their synaptic vesicle population in the wall of saphenous vein and artery from tilted rats to those obtained from rats which were maintained in horizontal, control position. It was hypothetized that adaptation of blood vessels to long-term gravitational loading might include also a morphological restructuring of the vascular adrenergic innervation.     

Transverse Vein Differentiation Associated with Gas Space Formation--Fate of the Middle Cell Layer in Leaf Sheath Development of Rice

In monocotyledons, the leaf vascular network consists of a hierarchicalsequence of vertical vascular bundles and numerous transverseveins that interconnect adjacent vertical veins. In the leafsheath of these species, especially grasses, lysigenous gascavities (gas spaces) are developed into intervascular spacesand provide a gas conducting system to non-aerial parts underflooded conditions. The spatial relationship between gas spaceformation and transverse vein differentiation was investigatedusing the leaf sheath of rice (Oryza sativa L.). Histochemicalobservation showed that patterns of differentiation of the transversevein are distinct from those of vertical vascular bundles. Onthe other hand, gas spaces are formed through the processesof cell death (collapse). Both events are initiated at a specificcell position in the middle layers of the leaf sheath, fromwhich the vascular system of the leaf is derived; this indicatesthat differentiation of transverse veins is associated withgas space formation. The cell-to-cell movement of fluoresceinisothiocyanate-conjugated dextran injected into middle layercells coincided with the area where cell collapse occurred,indicating a close relationship between the middle and adaxialcell layers, but not abaxial cell layers. A uniform cell numberbetween each transverse vein in the leaf sheath suggested theinvolvement of spatial regulation in transverse vein formationregardless of clonal history at the later stage of leaf veincanalization. Copyright 2000 Annals of Botany Company Cell collapse, leaf development, middle cell layer, microinjection, Oryza sativa L., rice, programmed cell death.     

MORPHOLOGY AND FINE STRUCTURE OF FISCHERELLA AMBIGUA1

Fischerella ambigua is a branching blue-green alga, the filamentous nature of which is maintained almost entirely by sheath material. Cell division in this organism most closely resembles the septal division found in most unicellular organisms. In all filamentous blue-green algae previously examined with the electron microscope, cell division has resulted from the imagination of the plasma membrane and inner wall layer only; both the middle wall and the outer wall layers remain continuous throughout the length of the filament. In Fischerella, by contrast, the plasma membrane and the inner wall layer invaginate to produce initially 2 cells. However, the middle wall layer, outer wall layer, and sheath also invaginate to separate the daughter cells. The sheath alone remains continuous throughout the length of the filament.     

Virilizing adrenal cancer and bail-out nephrectomy

We report a rare case of virilizing adrenal cancer with tumorous invasion of the left renal vein in which a retroperitoneal adrenalectomy with bail-out nephrectomy was performed. A tumor thrombus infiltrated the wall of the left adrenal vein and extended into the left renal vein. Initially, a kidney sparing procedure with partial tangential excision of the involved renal vein wall was performed. After positive vein margins were confirmed with intraoperative histology, the indication for nephrectomy was made. To the authors' awareness, this is the first report of a virilizing adrenal cancer with a tumor thrombus infiltration of the renal vein and surgical tendency for kidney preservation.     

Postsurgical changes of the opening angle of canine autogenous vein graft.

The opening angles of 30 canine autogenous vein grafts were measured to determine the postsurgical change of residual strain in the vein graft. Canine femoral veins were grafted to femoral arteries in the end-to-end anastomosis fashion. When harvested, the vein grafts were cut into short segments and the segments were cut open radially. The opened-up configurations were taken as the zero-stress states of the vessels. Opening angle, defined as the angle between the two lines from the middle point to the tips of the inner wall, was used to describe the zero-stress states. Results show that the opening angles (mean +/- SD) are 63.0 +/- 30.6 deg for normal femoral veins, and -0.4 +/- 4.6, 6.1 +/- 19.4, 25.4 +/- 20.1, and 47.8 +/- 11.4 deg for vein grafts at 1 day, 1 week, 4 and 12 weeks postsurgery, respectively. The postsurgical changes in opening angle reveal nonuniform transmural tissue remodeling in the vascular wall. The relations between the changes in opening angle and the changes in the morphology of the vein grafts are discussed. Intimal hyperplasia is correlated to the opening angle and is suggested to be the main factor for the postsurgical increase in opening angle. The longitudinal strain in the vein graft is found to decrease postsurgically.     

甘蔗叶不同部位ATP酶活性细胞化学定位

甘蔗叶片,叶鞘和肥厚带韧皮部 ATP 酶活性定位于筛管、伴胞的质膜、内质网和某些伴胞细胞基质、小囊泡和发育成熟的液泡上;叶片韧皮部薄壁细胞、厚壁细胞和厚壁通道细胞质膜及小囊泡中亦显示有 ATP 水解产物;维管束鞘细咆与厚壁细胞或厚壁通道细胞所构成的细胞间隙上也存在有 ATP 酶活性反应产物沉淀。甘蔗叶片大、中、小三种维管束,从小维管束到大维管束,面向细胞间隙的细胞表面上的 ATP 酶活性逐渐增强,而维管束鞘细胞质膜上的 ATP 酶活性则趋于减弱;同一维管束内则以韧皮部细胞的 ATP 酶活性最强。维管束鞘细胞与叶肉细胞之间存在很多的胞间连丝,并表现出高的 ATP 酶活性。讨论了 ATP 酶活性的分布状态与叶肉细胞的光合产物向韧皮部运输的关系。     

超氧化物歧化酶和Bcl-2在实验性精索静脉曲张大鼠睾丸中的变化

目的:建立大鼠实验性精索静脉曲张(experimental varicocele EV)的模式,测量睾丸中超氧化物歧化酶(superoxide dismutaseSOD)活性和Bcl-2的表达。方法:将40只雄性青春期Wistar大鼠随机分为EV8周组和12周组(各12只)和相应的假手术对照组2组(各8只),通过部分结扎左肾静脉建立大鼠EV模型,分别于术后8周、12周处死动物,测左侧精索静脉直径,用比色法测SOD 活力,免疫组化法测Bcl-2的表达。结果:成功建立了EV型,与相应的对照组相比左侧精索静脉直径明显增大(P<0.01)。光学显微镜下观察睾丸组织,发现大鼠睾丸生精上皮退变,曲细精管萎缩,间质水肿和精子发育阻滞。EV组双侧睾丸的SOD活性显著低于相应的对照组(P<0.01),左侧睾丸比右侧睾丸更低,但无明显统计学意义(P>0.05)。EV组双侧睾丸间质细胞中Bcl-2的染色指数与相应的对照组相比均显著降低(P<0.01),左侧睾丸染色指数比右侧睾丸下降更明显(P<0.01),EV12周组与 EV8周组相比,EV12周组染色指数更低(P<0.05)。SOD活性与Bcl-2的染色指数在0.01水平有显著相...     

Remodeling of the rat saphenous vein network in response to long-term gravitational load

Our main objective was to test whether chronic orthostatic body position induces network changes in the saphenous vein superficial tributary system of the rat. Fourteen male Sprague-Dawley rats were kept in tilted tube cages (45-degree head-up position) for two weeks to induce chronic gravitational load to their leg veins. Ten animals housed in normal cages and four animals kept in horizontally positioned tube cages served as controls. The whole superficial network of the left saphenous vein was microprepared surgically under anesthesia, superfused with saline and observed under a videomicroscope, while normal flow and pressure were maintained in the lumen. Branching angles, lengths of venous segments and their diameters were measured offline from digitized images using special image-analyzing software. Several branching angles at the popliteal confluence were significantly reduced by 12.5-15.8 %. The in vivo diameter of the main branch (936+/-34 vs. 805+/-44 microm) and of one of the popliteal tributaries (776+/-38 vs. 635+/-36 microm) increased (p<0.05), comparing vessels from tilted animals with those from normal controls. Maintaining the animals in horizontal tube cages did not induce the above alterations. The increased diameters and reduced branching angles of the saphenous vein network observed are adaptive responses of the venous network to a long-term gravitational load.     

Correlation between the distribution of lignin and pectin and distribution of sorbed metal ions (lead and zinc) on coir (Cocos nucifera L.)

Plant fibres are capacious for sorption of metal ions, and can be used in water cleaning. Knowledge about the sorption will help in selection of the fibre and optimisation of its chemical modification, if any. The aim of this paper is to investigate the connection, if any, between the distribution of lignin and pectin and the loading of Pb and Zn on coir (mesocarp fibres from Cocos nucifera L.). The coir consisted mainly of xylem and a fibre sheath. The lignin was evenly distributed in the cell walls of the fibre sheath, but in the xylem, there was no detectable content in the compound middle lamella, and a smaller content of lignin in the secondary walls than in the walls of the fibre sheath. The only detectable content of pectin in the fibre sheath walls was in the middle lamella, cell corners and extracellular matrix, while in the xylem, the pectin was almost evenly distributed in the wall, with a higher concentration in the middle lamella and cell corners. All cell walls facing the lacuna had a high content of pectin. The metal ions were mainly loaded on the xylem and cell walls facing the lacuna, maybe with an additional trend to be loaded on the large fibres. Lead was distributed on and across the whole secondary wall. Zinc was loaded on the secondary walls, but there was no information about the distribution across the wall. If there is a simple correlation between the loading of metal ions and the distribution of lignin or pectin, these investigations point at no correlation with lignin and a positive correlation with pectin. It has to be stressed that these conclusions are made on limited material and are therefore preliminary in nature.     

Kidney-targeted naked DNA transfer by retrograde injection into the renal vein in mice

We recently developed a novel kidney-targeted gene transfer technique in rats, using the retrograde renal vein injection of naked plasmid DNA. Many animal disease models are created in mice by transgenic or knockout technologies. However, it is much harder to perform renal vein injection in mice than in rats because they have a thin and short vein. Here we transferred the mouse interleukin (IL)-10 gene into mice by retrograde renal vein injection, using an IL-10 and immunoglobulin fusion protein (IL-10/Fc) (96-kDa) expression plasmid, pCAGGS-IL10/Fc. We observed a dose-response relationship between serum IL-10 levels and the amount of injected DNA. The serum IL-10 levels peaked at day 1 and then were sustained for at least 2 weeks. These results demonstrate that the kidney-targeted naked plasmid DNA transfer of mice by retrograde renal vein injection can be achieved, and the kidney serves as a depot organ for the production of large proteins.     

Demonstration of bacterial antigen in macrophages in experimental pyelonephritis

The immunomorphological characteristics of interstitial macrophages with PAS-positive granules were studied in experimental Escherichia coli pyelonephritis in rats, using an anti-E. coli antibody. Immunohistochemical, immunoelectron microscopical, as well as light- and electron microscopical findings were compared at twelve time points between 2 days and 13 weeks after infection. Macrophages with PAS-positive granules were present in the inflammatory infiltrates from the 7th day. The granules were phagolysosomes, filled predominantly with myelin figures. The myelin figures originated mainly from the constituents of the bacterial wall and reacted with the anti-E. coli antibody even 13 weeks after infection. The storage of bacterial residues with preserved antigenic structures for several weeks after infection indicates disturbed phagolysosomal elimination of the bacterial substances in the PAS-positive macrophages. In the formation of macrophages with PAS-positive granules, lysosomal overloading with large amounts of bacteria and cell debris is assumed, leading to consumption of the lysosomal enzymes, consequent incomplete breakdown and retention of the bacterial residues.     

Modification of glass channel walls for separation of biological particles by gravitational field-flow fractionation

In the gravitational field-flow fractionation of complex samples, various interaction and adsorption phenomena can occur in separation channels that influence fractionation and complicate the explanation of resulting fractograms. To overcome these problems, the glass surface was modified to create charge-free, non-adsorbing hydrophilic media for the mild treatment of hydrophilic biological particles. The modification was carried out in two steps: (1) by a simple lacquering of the glass surface with polystyrene diluted in toluene and (2) subsequent adsorption of a detergent layer on polystyrene. Essential suppression of ionic interactions between soluble low-molecular-mass compounds and the channel wall and decreased adsorption effects were demonstrated in separations of blood samples by gravitational field-flow fractionation.     

Morphology of the wall of some main arteries normally and in limited motor activity]

Effects of different periods of hypokinesia upon the structure of the main arteries wall and the microcirculatory bed of the aorta adventitia were studied in rabbits by histological methods. It was shown that hypokinesia lasting more than 4 weeks resulted in the atrophy of the medical sheath and dystrophy of the elastic framework in the wall of main arteries. In the microcirculatory bed of the aorta adventitia there occurred blood stagnation, the integrity of the microvessels wall (mainly capillaries, postcapillaries and venules) was broken. The degree of the above morphological changes depends on duration of hypokinesia.     

Growth initiation in the geotropic response of the wheat node

Summary The geotropic response in stems of Triticum aestivum occurs at the leaf sheath bases. Growth is initiated in the lower halves of these organs after orientation into the horizontal position. Lateral transport of growth hormone is not involved in the development of curvature. Continuous stimulation is necessary to maintain the response.Growth can be initiated in small pieces of tissue excised from the leaf sheath base but this is entirely dependent upon the precise orientation of the tissue in the gravitational field. Growth occurs only when the segment is orientated horizontally with the outer epidermis facing downwards. IAA is able to initiate growth in nongeo-induced tissue segments of the leaf sheath base but this effect appears to differ from the geo-induced growth.IAA-Indole-3-acetic acid; ABA-RS(±) abscisic acid; CFM-chlorofluorenol methyl ester; GA₃-gibberellic acid.     

Changes in ultrastructure and actomyosin complex of cardiomyocytes in experimental hypergravitation

There were studied the cardiomyocyte ultrastructure, contractile function, actomyosin complex composition and property of the rat ventricular myocardium after repeated gravitational overloading and following rest. In the hypergravitation period cardiomyocyte changes carry destructive character or are regenerative processes manifestation. They are comparable with myocardial contractile function state and with displacements in molecular structure of myofibrillar apparatus. At rest conditions the liquidation of cardiomyocytes destructive changes falls behind the normalization of contractile and regulatory cells of physico-chemical characteristics. The possible reasons of this phenomenon are discussed.     

平颜三节叶蜂属一新种暨中国种类检索表(膜翅目:三节叶蜂科)

记述采自浙江的膜翅目三节叶蜂科平颜三节叶蜂属1新种:短顶平颜三节叶蜂Aprosthema brevivertexis Wei sp.nov..该种与同域分布的天目平颜三节叶蜂A.tianmunicum Wei& Wen,2000近似,但前翅翅痣下方具明显烟褐色横斑,1Rs显著长于2Rs室,Rs脉第2段1.3倍于Rs脉第3段长;单眼后区宽长比等于2.2,后部不高于单眼面;颚眼距稍窄于单眼直径;中胸背板前叶无中纵沟,具细纵脊;背面观锯鞘互相远离,侧面观锯鞘端部急尖等,与后者不同.     

平颜三节叶蜂属一新种暨中国种类检索表(膜翅目:三节叶蜂科)

记述采自浙江的膜翅目三节叶蜂科平颜三节叶蜂属1新种:短顶平颜三节叶蜂Aprosthema brevivertexis Wei sp.nov..该种与同域分布的天目平颜三节叶蜂A.tianmunicum Wei& Wen,2000近似,但前翅翅痣下方具明显烟褐色横斑,1Rs显著长于2Rs室,Rs脉第2段1.3倍于Rs脉第3段长;单眼后区宽长比等于2.2,后部不高于单眼面;颚眼距稍窄于单眼直径;中胸背板前叶无中纵沟,具细纵脊;背面观锯鞘互相远离,侧面观锯鞘端部急尖等,与后者不同.