Muscle membrane material

Factors that affect texture include moisture content, composition, variety or species, pH, product history (maturation or age), and sample dimensions. Texture is also dependeut on the method of dehydration and pretreatments. Purslow [55] stated that meat texture is affected by the structure of the solid matrix. He coucluded that it is important to have a fundamental understanding of the fracture behavior of meat and how it relates to the structure of the material. Stanley [83] stated that many researchers now believe that the major structural factors affecting meat texture are associated with connective tissues aud myofibrillar proteins. Moreover, two other components muscle membranes and water also deserve consideration not because of their inherent physical properties, but rather as a result of the indirect influence they have on the physical properties. It should be noted that sarcoplasmic proteins may be important for the same reason, although little information on their role is available. He suggested that these structures merit particular attention. 

The s-IBM muscle-fiber cytoplasm also contains (a) collections of 6-10 nm amyloid-like fibrils (b) fine flocculo-membranous material and (c) amorphous material these three contain A 3 immunore-activity [19]. We recently demonstrated that 6-10 nm amyloid-like fibrils preferentially contain A 342 immunoreactivity [8] (see Figure 7.3a in this volume). The combination of tau-positive PHFs plus A 342-positive collections of 6-lOnm amyloid-like fibrils within muscle fibers is currently considered diagnostic of s-lBM. 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

Muscle biopsy shows vacuolar myopathy of very severe degree affecting all fibers in Pompe s disease but of varying degree and distribution in childhood and adult AMD. In adult AMD, biopsy specimens from unaffected muscles may appear normal by light microscopy. The vacuoles contain PAS-positive material, a marker for glycogen. Electron microscopy shows abundant glycogen, both within membranous sacs, presumably lysosomes, and free in the cytoplasm. 

Schneider et al. (S6, S7, S8) have demonstrated that wheat gluten and certain gluten fractions cause inhibition of the isolated small intestine of the rat. In the Trendelenburg preparation, as modified by Biilbring et al. (B21), inhibition of the peristaltic reflex occurred if the material was placed outside the intestine so that it could reach the muscle without traversing the mucous membrane. If it was placed inside the lumen no inhibitory effect was seen. If the gluten or gluten fractions were incubated with rat mucous membrane extract, complete inactivation of the inhibitory effect was obtained. This action of mucous... 

Online dialysis and subsequent trace enrichment has been further described for isolation/purification of flumequine residues from fish muscle (203), or oxolinic acid and flumequine from chicken liver (193) and salmon muscle (204). This involves online purification by diphasic dialysis membrane and trapping of the analytes onto a liquid chromatographic preconcentration column (reversed-phase Ci8 or polymeric), rinsing of the coextracted materials to waste, and finally flushing of die concentrated analytes onto the analytical column. 

The thin (8 nm) outer cell membrane or "plasma-lemma" (Fig. 1-7) controls the flow of materials into and out of cells, conducts impulses in nerve cells and along muscle fibrils, and participates in chemical communication with other cells. Deep infoldings of the outer membrane sometimes nm into the cytoplasm. An example, is the "T system" of tubules which functions in excitation of muscle contraction (Figs. 19-7, 19-21). Surfaces of cells designated to secrete materials or to absorb substances from the surrounding fluid, such as the cells lining kidney tubules and pancreatic secretory cells, are often covered with very fine projections or microvilli which greatly increase the surface area. 

Thousands of different proteins make up a very large fraction of the "machinery" of a cell. Protein molecules catalyze chemical reactions, carry smaller molecules through membranes, sense the presence of hormones, and cause muscle fibers to move. Proteins serve as structural materials within cells and between cells. Proteins of blood transport oxygen to the tissues, carry hormones between cells, attack invading bacteria, and serve in many other ways. No matter what biological process we consider, we find that a group of special proteins is required. 

Calcium ions entering cells from the outside or released from internal stores trigger many biological responses (see Box 6-D). Within cells Ca2+ often accumulates in mitochondria, in the ER, or in vesicles called calciosomes.265 Release of the stored Ca2+ is induced by hormones or by nerve impulses. For example, impulses flow from the nerve endings into the muscle fibers and along the invaginations of the plasma membrane called transverse tubules (Chapter 19). There they induce release of Ca2+ from the ER. The released ions activate enzymes266 and induce contraction of the muscle fibers. In many cells, Ca2+ causes release of secreted materials, for example, neurotransmitters in the brain 267/268... 

Many important biological substances do not form crystals. Among these are most membrane proteins and fibrous materials like collagen, DNA, filamentous viruses, and muscle fibers. Some membrane proteins can be crystallized in matrices of lipid and studied by X-ray diffraction (Chapter 3, Section III.D), or they can be incorporated into lipid films (which are in essence two-dimensional crystals) and studied by electron diffraction. I will discuss electron diffraction later in this chapter. Here I will examine diffraction by fibers. 

In both the studies of Wight and Ross, and of Eisenstein and Kuettner, ruthenium red staining material was also found in the plasma membranes of endothelial cells and smooth muscle cells which was not removed with chondroitinase ABC and is therefore not chon-droitin sulfate or dermatan sulfate. 

Actin and tubulin are two important cellular components that are involved in cell shape and movement. Actin is present in all mammalian cells and is involved in cellular transport and phagocytosis (eating of extracellular materials), provides rigidity to cell membranes, and when bonded to tropomyosin and troponin, forms the thin filaments of muscle. Thbulin is the subunit from which microtubules are self-assembled. Microtubules are most commonly known for their role in cell division. The mechanisms of self-assembly of these macromolecules have been well studied and are important models of biological assembly processes. Below we examine each of these processes. 

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