Dense bodies

The primary objective of sintering is to produce a cohesive body of the desired size and shape having a microstmcture that optimizes the desired in-use properties. For ceramics, this is usually a theoretically or nearly theoretically dense body comprised of fine (micrometer size), uniform grains. 

Other types of refractory that find use are forsterite, zirconia, and zircon. Acid-resisting bricks consisting of a dense body like stoneware... 

Smooth muscles, as the name implies, do not contain sarcomeres. In fact, it was initially difficult to demonstrate the presence of thick filaments in smooth muscle, although their presence is now well-established. On the other hand, it is very difficult to demonstrate thick filaments in highly motile cells, such as macrophages and neutrophils, and this may reflect the necessity to rapidly form and redistribute cytoskeletal elements during migration. Thick filaments in smooth muscles appear to be considerably longer than those in striated muscles. They run diagonally in smooth muscle cells and attach to the membrane at structures known as dense bodies. Thus, there is a cork-screw effect when smooth muscles contract (Warshaw etal., 1987). 

Another actin binding protein, the large 100 kDa a-actinin, crosslinks actin filaments together at the dense bodies and near the points of actin filament attachment to the cell membranes, a-actinin is also associated with still another actin binding protein, vinculin, which may stabilize both the Z-line like dense bodies and the membrane attachments. 

The superstructure of smooth muscle actin filaments is differentiated from those of striated muscle by the absence of the troponins and the lateral organization by association of the filaments with dense bodies instead of with the Z-line. How these differences are encoded is again not at all clear. However, the myofibrillar structure and the alignment of the alternating actin and myosin filaments is apparently due primarily to dense bodies and the actin-actinin macrostructures. As the bent dumbbell shaped actins assemble into filaments they are all oriented in the same direction. The S-1 fragments of myosin will bind to actin filaments in vitro and in... 

Apart from offering a new and highly specific approach to the inhibition of herpesviruses, this new mechanism of action could potentially also have beneficial immunological consequences. During treatment with BAY 38-4766, viral protein synthesis continues, but due to the lack of monomeric genomic length DNA, only empty particles (dense bodies) can be formed. It is conceivable that these non-infections viral particles could aid the establishment of an antiviral immune response, leading to better control of the virus by the host. This mechanism appears... 

Other types of refractory that find use are forsterite, zirconia, and zircon. Acid-resisting bricks consisting of a dense body like stoneware are used for lining tanks and conduits in the chemical industry. Carbon blocks are used as linings for the crucibles of blast furnaces, very extensively in a number of countries and to a limited extent in the United States. Fusion-cast bricks of mullite or alumina are largely used to line glass tanks. 

PLATELETS. Platelets are nonnucleated discoid or elliptical cells that originate from the fragmentation of giant polyploid megakaryocytes located in the bone marrow. The average diameter of the platelet is 1.5 pm. Each platelet is surrounded by a trilaminar membrane, and its cytoplasm contains a dense body (delta granule), a surface-connected canalicular system,... 

Because there are no sarcomeres in smooth muscle, there are no Z lines. Instead, the actin filaments are attached to dense bodies. These structures, which contain the same protein as Z lines, are positioned throughout the cytoplasm of the smooth muscle cell as well as attached to the internal surface of the plasma membrane. Myosin filaments are associated with the actin filaments, forming contractile bundles oriented in a diagonal manner. This arrangement forms a diamond-shaped lattice of contractile elements throughout the cytoplasm. Consequently, the interaction of actin and myosin during contraction causes the cell to become shorter and wider. 

FIGURE 1-6 A portion of a Golgi apparatus. The smooth-mem-braned cisternae appear beaded. The many circular profiles represent tangentially sectioned fenestrations and alveolate vesicles (primary lysosomes). Two of the latter can be seen budding from Golgi saccules (arrows). Mitochondria and a dense body (secondary lysosomes) are also present. x60,000. 

Somlyo Dil18 stains the whole plasma membrane and we can t tell the difference between the caveolae and the non-caveolar membrane. We also have a pretty good idea that when we see dense bodies this pretty much excludes SR and caveolae. At this resolution we would not want to distinguish caveolae. The best lateral resolution a confocal will give is about 0.2 fim, and by the time you get close to... 

Textural mesoporosity is a feature that is quite frequently found in materials consisting of particles with sizes on the nanometer scale. For such materials, the voids in between the particles form a quasi-pore system. The dimensions of the voids are in the nanometer range. However, the particles themselves are typically dense bodies without an intrinsic porosity. This type of material is quite frequently found in catalysis, e.g., oxidic catalyst supports, but will not be dealt with in the present chapter. Here, we will learn that some materials possess a structural porosity with pore sizes in the mesopore range (2 to 50 nm). The pore sizes of these materials are tunable and the pore size distribution of a given material is typically uniform and very narrow. The dimensions of the pores and the easy control of their pore sizes make these materials very promising candidates for catalytic applications. The present chapter will describe these rather novel classes of mesoporous silica and carbon materials, and discuss their structural and catalytic properties. 

The lysosomal acid phosphatase was cytochemically shown to be present in dense bodies of chondrocytes but not in the nearly matrix vesicles461,462). Subsequent studies have confirmed that the amount of acid phosphatase in isolated vesicles is low and also that the activities of -glucuronidase and cathepsin D in the isolated vesicles were negligible463). The evidence indicates that matrix vesicles are not lysosomal. Isolated vesicles contain comparatively little mitochondrial succinic dehydrogenase, suggesting that the matrix vesicles and mitochondria were not identical458). 

Thybeig, J., Friberg, U. Ultrastructure and phosphatase activity of matrix vesicles and cytoplasmic dense bodies in the epiphyseal plate. J. Ultrastruct. Res. 33, 554 (1970)... 

When we have a perfectly cleansed and purified piece of carbon, there is no ash left. The carbon bums as a solid dense body, that heat alone cannot change as to its solidity, and yet it passes away into vapour that never condenses into solid or liquid under ordinary circumstances and what is more curious still, is the fact that the oxygen does not change in its bulk by the solution of the carbon in it. Just as the bulk is at first, so it is at last, only it has become carbonic acid. 

Although much of the focus has been on the DPC of striated muscle, it is likely that desmin attachments to dense plaques of smooth muscle play critical roles in regulating the transmission of contractile forces in this tissue as well. This is particularly relevant in light of the observed defects in smooth muscle of desmin-deficient mice, in which active force per cross-sectional area was reduced to 40% of controls of smooth muscle tissue (Sjuve et al, 1998). IFAP candidates for serving this linking function are plectin and other components of the actin-rich cortex, including calponin (which also plays a role in the cytoplasm of smooth muscle cell dense bodies see below), and the spectrin/ankyrin complex. 

In departing from the sun light strikes the dense bodies, the celestial as well as the terrestrial it places their faculties in movement, carries them with it, reflects them and diffuses them in the upper Air as well as in the lower. Air having a disposition to mix with the Water and the Earth, becomes the vehicle of these faculties, and communicates them to the bodies which are formed of them, or which are by analogy most susceptible of them. These are the faculties which are called influences. Many natural philosophers deny their existence, because they do not know them. 

This igneous spirit, bom into bodies by the rays, is easily distinguished from them. The latter are communicated only as long as they find in their way no opaque bodies which arrest their course. The former penetrates even the most dense bodies, since we feel the heat on the side of a wall opposite to that on which the rays fall, although they have not been able to penetrate it. This heat exists even after the rays have disappeared with the luminous body. 

This formula can be used to convert the values of permittivity found for porous bodies to the value expected for fully dense bodies. 

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