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11.
Striated muscle fibers (or cells) were observed in three of the six swine pineal glands. The muscle fibers occurred in clusters of several fibers about the parenchymal blood vessels. They were in general poorly developed, lacked regular cross striations and were not readily recognized histologically. The muscle fibers were, however, easily identified on electron microscopy because of the myofilaments they contain. In most of the muscle fibers, the myofilaments were arranged in ill-defined, disorderly bundles and rarely formed well-defined myofibrils and sarcomeres. The sarcotubular system was also poorly developed and triads were sparse and randomly scattered. Leptomeres were observed in several muscle fibers. The source of the muscle fibers in the pineal glands is not well understood and, whatever the source may be, the muscle fibers seem to remain poorly developed in the pineal glands. 相似文献
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In order to carry out investigations in the course of sport activities of children an efficient telemetering device is essential, which can also be used on children. The Kinderspital Salzburg has developed a telemetry system in cooperation with the Technische Versuchs- und Forschungsanstalt der Technischen Hochschule Wien and the Messerschmitt-B?lkow-Blohm-Werke München. For the first time in this field a Pulse Code Modulation (P.C.M.) System was utilized, implying high accuracy on data transmission and recovery as required for scientific examinations. The children's physical capacity is determined on a bicycle ergometer, and the performance measured in this fashion is then compared with the performance achieved in sport. 相似文献
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Purified rat liver nuclei covalently bound low levels of seven aromatic [14C]hydrocarbons to nuclear DNA. Induction with 3-methylcholanthrene increased the binding of six carcinogenic hydorcarbons, but did not raise the level of binding of noncarcinogenic anthracence. Removal of the nuclear envelope by Triton N-101 eliminated binding and aryl hydrocarbon hydroxylase activities and cytochrome P-450 from the nuclei. Binding of two of two strong carcinogens, benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene, to nuclear DNA was compared to the levels of aryl hydrocarbon hydroxylase and cytochrome P-450 in nuclei from uninduced and benz[a]anthracene-, 3-methylcholanthrene-, and phenobarbital-induced rats. Microsomal hydroxylase and cytochrome P-450 were also assayed. Induction with 3-methylcholanthrene gave the largest increases in nuclear activities: 11 times as much hydroxylase, 6 times as much cytochrome P-450, and 4 times as much binding of both hydrocarbons. Benz[a]anthracene and phenobarbital induced these nuclear activities 0- to 4-fold. In the presence of added NADPH, binding of benzol[a]pyrene to DNA by nuclei increased rapidly for at least 20 min. When NADPH was not added, the reaction stopped at a low level in 5 min. When CO was bubbled through the reaction mixture with or without added NADPH, binding of benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene was partially inhibited, indicating that cytochrome P-450 plays a role in this activation. Since no nuclear hydroxylase activity was seen without added NADPH or in the presence of CO, activation and subsequent binding of hydrocarbons to nuclear DNA, at least in part, does not require the activated oxygen used in monooxygenase reactions. 相似文献
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In times of increasing energy costs automotive light weight construction is gaining more importance. The production of hybrid compounds by forging is a promising method for manufacturing functional parts by applying resource‐saving process steps. The mechanical properties of these parts can be specifically adapted to the requirements. In compound forging of steel‐aluminum parts the two materials need to be heated to different forming temperatures. In this paper, the challenges and their methods for the development of a heating and forming strategy based on different material characteristics are presented. 相似文献
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MD Rekhter N Shah RD Simari C Work JS Kim GJ Nabel EG Nabel D Gordon 《Canadian Metallurgical Quarterly》1998,98(13):1335-1341
BACKGROUND:Smooth muscle cell (SMC) replication plays a central role in the pathogenesis of transplant arteriosclerosis. One strategy to eliminate dividing cells is to express a herpesvirus thymidine kinase (tk) gene that phosphorylates the nucleoside analogue ganciclovir into a toxic form leading to cell killing. However, medial SMCs are resistant to gene transfer unless the artery undergoes deendothelialization. We hypothesized that manipulations that increase the \"porosity\" of the artery can make SMCs prone to gene transfer without denudation. METHODS AND RESULTS:In organ culture of rabbit aorta, longitudinal stretch and supraphysiological pressure applied for 3 hours during incubation with adenoviral vector facilitated gene transfer into medial SMCs without denudation. Of the SMCs, 10.2+/-3.8% expressed a reporter gene of human placental alkaline phosphatase (hpAP), whereas SMCs in control arteries did not express hpAP. To evaluate the feasibility of transgene expression in arterial grafts, we performed such permeabilization-assisted reporter gene transfer into aortas of donor Dutch Belted rabbits and transplanted them into carotid arteries of recipient New Zealand White rabbits. Unstretched transfected grafts were used as a control. SMCs expressed hpAP (7. 3+/-2.4% of cells in 2 days and 4.2+/-1.9% in 2 weeks) in stretched grafts only. In the next series of experiments, we transfected stretched grafts with ADV-tk and combined transplantation with systemic administration of ganciclovir. Stretched ADV-hpAP grafts were used as a control. In 2 weeks, the formation of intimal thickening in tk-expressing grafts was significantly reduced (P<0. 01) because of a decrease in proliferating SMCs. CONCLUSIONS:Manipulations within target tissues can enhance the efficiency of gene transfer into SMCs. Although mechanical permeabilization is clinically problematic, in principle, targeting SMC replication may provide a genetic approach to the treatment of transplant arteriosclerosis. 相似文献
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The effects of enhanced HSP27 expression or expression of a nonphosphorylatable form of HSP27 on the migration of bovine arterial endothelial cells was assessed. Expression of the wild-type protein enhanced migration by twofold compared to control transfectants, whereas expression of the mutant protein retarded migration by 40%. Since homologs of the small heat shock protein inhibit F-actin polymerization in vitro and may alter basolateral F-actin content in vivo, it was postulated that the 27 kDa heat shock protein affects microfilament extension essential for cell motility. Expression of the wild-type protein promoted the generation of long cellular extensions, whereas expression of the dominant negative mutant protein resulted in a marked reduction of lamellipodia and generated aberrant microfilament morphology at the wound edge. Immunofluorescence combined with phalloidin staining demonstrated the colocalization of the HSP27 gene products with lamellipodial microfilament structures. These data suggest that the 27 kDa heat shock protein regulates migration by affecting the generation lamellipodia microfilaments. 相似文献
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