Connective tissue lipid

The citric acid cycle is the final common pathway for the aerobic oxidation of carbohydrate, lipid, and protein because glucose, fatty acids, and most amino acids are metabolized to acetyl-CoA or intermediates of the cycle. It also has a central role in gluconeogenesis, lipogenesis, and interconversion of amino acids. Many of these processes occur in most tissues, but the hver is the only tissue in which all occur to a significant extent. The repercussions are therefore profound when, for example, large numbers of hepatic cells are damaged as in acute hepatitis or replaced by connective tissue (as in cirrhosis). Very few, if any, genetic abnormalities of citric acid cycle enzymes have been reported such ab-normahties would be incompatible with life or normal development. 

Several of these morphological factors are illustrated in Figure 1. Figure lA is of the fat portion of bacon and has been stained for connective tissue. It is noted that fat tissue is not all lipid but has an extensive connective tissue component ranging from fairly thick layers to delicate layers defining each adipose cell. Figure IB is from a finely chopped emulsion. Connective tissue pieces are stained dark, the protein matrix is gray and the... 

Atherosclerosis is a wide-spread pathology, manifested chiefly by the deposition of cholesterol in arterial walls, which results in the formation of lipid plaques (atheromas). Lipid plaques are specific foreign bodies around which the connective tissue develops abnormally (this process is called sclerosis). This leads to the cal-cification of the impaired site of a blood vessel. The blood vessels become inelastic and compact, the blood supply through the vessels is impeded, and the plaques may develop into thrombi. 

It has been shown that lung macrophages from patients with systemic sclerosis (SS) produced the elevated levels of nitric oxide, superoxide, and peroxynitrite and expressed the enhanced level of iNOS [281], NAC administration reduced peroxynitrite production and might be possibly recommended for the treatment SS patients. Solans et al. [282] found the significant enhancement of lipid peroxidation in erythrocytes from SS patients. Cracowski et al. [283] showed that in vivo lipid peroxidation was enhanced in scleroderma spectrum disorders including SS and undifferentiated connective tissue disease. 

The interactions of these cells with T lymphocytes also in the lesion and the overlying endothelium can lead to a massive flbroproliferative response over which connective tissue from smooth muscle cells form a fibrous cap. This covers the advanced lesion or fibrous plaque of atherosclerosis, deeper portions of which consist of macrophages, T lymphocytes, smooth muscle cells, connective tissue, necrotic debris and varying amounts of lipids and lipoproteins. 

The atherosclerotic plaque consists, on the lumen side, of a layer of connective tissue containing smooth muscle cells and macrophages covering a deeper layer of macrophages containing so much hpid that they are known as foam cells due to their microscopic appearance. This layer also contains a varying amount of cell debris and extracellular lipid. Outside it, there is often a region of proliferated smooth muscle cells. 

Ethanol-related high levels of NADH+H and acetyl-CoA in the liver lead to increased synthesis of neutral fats and cholesterol. However, since the export of these in the form of VLDLs (see p. 278) is reduced due to alcohol, storage of lipids occurs (fatty liver). This increase in the fat content of the liver (from less than 5% to more than 50% of the dry weight) is initially reversible. However, in chronic alcoholism the hepatocytes are increasingly replaced by connective tissue. When liver cirrhosis occurs, the damage to the liver finally reaches an irreversible stage, characterized by progressive loss of liver functions. 

Filter supernatant through two layers of cheesecloth to remove lipid and connective tissue particles. 

The linear polypeptide chains of a protein fold in a highly specific way that is determined by the sequence of amino acids in the chains. Many proteins are composed of two or more polypeptides. Certain proteins function in structural roles. Some structural proteins interact with lipids in membrane structures. Others aggregate to form part of the cytoskeleton that helps to give the cell its shape. Still others are the chief components of muscle or connective tissue. Enzymes constitute yet another major class of proteins, which function as catalysts that accelerate and direct biochemical reactions. 

Intratracheal administration of l-(chloromethyl)silatrane into the lungs increases its weight due to fibrogenesis of the connective tissue, growth of lymph nodes and an increase in the lipid and collagen contents of the lungs. 

The atherosclerotic lesions develop in a complex, chronic process. The first detectable lesion is the so-called fatty streak, an aggregation of lipid-laden macrophage foam cells. The next stage of development is the formation of plaques consisting of a core of lipid and necrotic cell debris covered by a layer of connective tissue and smooth muscle cells. These plaques hinder arterial blood flow and may precipitate clinical events by plaque rupture and thrombus formation. Platelets from the thrombi, activated macrophages, and smooth muscle cells release growth factors and cytokines resulting in an inflammatory-fibroproliferative response that leads to the advanced lesions of atherosclerosis. 

Although much of the interest in biological nanostructures has focused on relatively complex functionality, cells and organisms themselves can be considered as a collection of self-assembled materials lipid bilayers, the extracellular matrix, tendon and connective tissue, skin, spider silk, cotton fiber, wood, and bone are all self-assembled biological materials, with an internal structure hierarchically ordered from the molecular to the macroscopic scale. 

N-acetylglucosamine (see Chapter 9) is a component of glycoproteins, connective tissue proteoglycans, and complex lipids. It may be synthesized in the human organism from fructose-6-phosphate, as indicated in Figure 18.17. N-acetylglucosamine is also a precursor of N-acetylmannosamine, which along with pyruvic acid participates in the biosynthesis of sialic acid. 

Differential diagnoses of peripheral neuropathy were entertained. Laboratory tests revealed that serum parameters for electrolytes and proteins were all within the normal range. Urine porphyrinogen and porphobilinogen levels were normal. Tests were negative for serum rheumatoid factor and antinuclear antibodies, the latter used in detection of connective tissue diseases such as systemic lupus erythematosus and polyarteritis nodosa that could present with features of peripheral neuropathy. Nerve conduction studies of the radial, ulnar, and median nerves revealed delayed conduction. Biopsies of the ulnar and radial nerves showed loss of nerve fibers and sudanophilic (indicating lipid) deposits in the Schwann cells of the neurons. Similarly, the yellowish plaques of the pharynx showed abundant macrophages filled with sudanophilic material. These deposits were not membrane-bound. 

Human recombinant growth hormone connective tissue, mineral, protein, carbohydrate, and lipid metabolism... 

Although proteins are large molecules they are small compared with a cell and even with supramolecular structures which may be part of a cell, such as plasma and organelle membranes, ribosomes, chromosomes, filaments, enzyme complexes and viruses (Chap. 1). Supramolecular structures are also prominent outside cells and are, for example, essential components of connective tissues such as tendon, ligament, cartilage and bone. Supramolecular structures can consist of a variety of different types of molecule from the small (such as membrane lipids) to macromolecules (such as proteins, DNA and RNA). 

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