Muscle components

An additional and widespread neuroactive (transmitter-like) compound is nitric oxide (NO). This gaseous secretion is a product of the action of the enzyme NO-synthase on arginine. It is implicated in at least two roles within the non-sensory tissues of the organ, and at particular synapses in the AOB. One nitric oxidergic effect is initiated by the nerve fibres supplying the smooth muscle component of the vasomotor tissues. The other effect is the expected action of NO on the output... 

Boyer, I.J., D.A. Cory-Slechta, and V. Di Stefano. 1985. Lead induction of crop dysfunction in pigeons through a direct action on neural or smooth muscle components of crop tissue. Jour. Pharmacol. Exp. Ther. 234 607-615. 

To understand the physiological nature of muscle contractions, it is helpful to examine muscles microscopically. Muscle fibers have an outside membrane called the plasmalemma, an interior structure called a sar-colemma, transverse tubules across the fibers, and an inner network of muscle tissue called sarcoplasma. When a nerve impulse reaches the muscle, an action potential is set up and the current quickly travels in both directions from the motor end plate through the entire length of the muscle fiber. The whole inside of the muscle tissue becomes involved as the current spreads and, aided by calcium, the contractile protein called actin causes the muscle component (myosin) to contract. An enzyme, ATP-ase, helps provide the energy needed for the muscular filaments to slide past each other. Relaxation occurs promptly when Ca flows into the muscle tissue and the cycle is completed. The muscle fiber is now ready to be stimulated again by a nerve impulse. 

A standardized approach has been developed for arriving at a method for isolation of purified plasma membrane from each of various smooth muscles (31-41 see 26,33,34). It starts with a very careful dissection to remove all possible cells other than smooth muscle. Studies have shown that what appears to be a minor contamination by non-smooth muscle components (eg. fat cells or adventitia of blood vessels) may markedly affect the overall properties of the subsequent membrane fractions isolated (36). Since many smooth muscle organs contain two or more layers of muscle which often differ in their physiological (42), pharmacological (43) and isolated membrane properties (44), it is always desirable to separate muscle layers and to isolate their membranes individually. There are inevitably a few fibroblasts and nerves left in the most carefully dissected smooth muscle tissue so far, no one has compared these properties of membranes from smooth muscle tissue to those from freshly isolated smooth muscle cells to determine if these residual contaminent membranes affect the properties of the membranes from tissues we think not. 

Eble JN, Amin MB, Young RH. Epithelioid angiomyolipoma of the kidney a report of five cases with prominent and diagnostically confusing epithelioid smooth muscle component. Am J Surg Pathol. 1997 21 1123-1130. 

As occurs for fibrous amartomatous lesions elsewhere in the body, this extremely rare, probably dysembriogenetic lesion is characterized by the presence of tissue maintaining the same histological features of the normal cavernosal bodies, but with altered architecture by the presence of increased fi-brotic component and reduced vascular and smooth muscle components. 

Urine is stored and evacuated by the bladder. The smooth muscle component of the bladder wall is termed the detrusor. The detrusor consists of interlacing musde bundles that interdigitate with one another, resulting in a complex meshwork of smooth muscle. Viscoelastic properties of the normal detrusor allow it to stretch significantly without a significant rise in tension pressure. Detrusor fibers... 

Fig. 13.3a-c Normal rectus femoris muscle, a-c Schematic drawings of a coronal view through the anterior thigh illustrate the inner and outer components of the rectus femoris muscle, a The outer part of this muscle arises from the direct tendon (DT) and expands from the posterior surface of the superficial aponeurosis (SA) to attach into the anterior aspect of the distal deep aponeurosis (DA), b The inner part of the rectus femoris is connected proximally to the indirect tendon (IT) and arises from the lateral and medial surfaces of the central aponeurosis (CA) to insert into the anterior aspect of the distal aponeurosis, c Combined view of both muscle components... 

Improta et al., 1996] Improta, S., Politou, A., and Pasture, A. Immunoglobulinlike modules from titin I-band extensible components of muscle elasticity. Structure. 4 (1996) 323-337... 

Rya.nia., The root and stem of the plant yania speciosa family Flacourtiaceae, native to South America, contain from 0.16—0.2% of iasecticidal components, the most important of which is the alkaloid ryanodine [15662-33-9] C25H250 N (8) (mp 219—220°C). This compound is effective as both a contact and a stomach poison. Ryanodine is soluble ia water, methyl alcohol, and most organic solvents but not ia petroleum oils. It is more stable to the action of air and light than pyrethmm or rotenone and has considerable residual action. Ryania has an oral LD q to the rat of 750 mg/kg. The material has shown considerable promise ia the control of the European com borer and codling moth and is used as a wettable powder of ground stems or as a methanohc extract. Ryanodine uncouples the ATP—ADP actomyosia cycle of striated muscle. 

The sacroplasmic proteins myoglobin and hemoglobin are responsible for much of the color in meat. Species vary tremendously in the amount of sacroplasmic proteins within skeletal muscle with catde, sheep, pigs, and poultry Hsted in declining order of sarcoplasmic protein content. Fat is also an important component of meat products. The amount of fat in a portion of meat varies depending on the species, anatomy, and state of nutrition of the animal. The properties of processed meat products are greatiy dependent on the properties of the fat included. Certain species, such as sheep, have a relatively higher proportion of saturated fat, whereas other species, such as poultry, have a relatively lower proportion of saturated fat. It is well known that the characteristic davors of meat from different species are in part determined by their fat composition. 

Many patents have been issued on the use of pyrogaUol derivatives as pharmaceuticals. PyrogaUol has been used extemaUy in the form of an ointment or a solution in the treatment of skin diseases, eg, psoriasis, ringworm, and lupus erythematosus. GaUamine triethiodide (16) is an important muscle relaxant in surgery it also is used in convulsive-shock therapy. Trimethoprim (2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine) is an antimicrobial and is a component of Bactrin and Septra. Trimetazidine (l(2,3,4-trimethoxybenzyl)piperazine (Vastarel, Yosimilon) is used as a coronary vasodilator. l,2,3,4-Tetrahydro-6-methoxy-l-(3,4,5-trimethoxyphenyl)-9JT-pyrido[3,4- ]indole hydrochloride is useful as a tranquilizer (52) (see Hypnotics, sedatives, ANTICONVULSANTS, AND ANXIOLYTICS). Substituted indanones made from pyrogaUol trimethyl ether depress the central nervous system (CNS) (53). Tyrosine-and glycine(2,3,4-trihydroxybenzyl)hydrazides are characterized by antidepressant and anti-Parkinson activity (54). 

Sutures are required to hold tissues together until the tissues can heal adequately to support the tensions exerted on the wound duting normal activity. Sutures can be used ia skin, muscle, fat, organs, and vessels. Nonabsorbable sutures are designed to remain ia the body for the life of the patient, and are iadicated where permanent wound support is required. Absorbable sutures are designed to lose strength gradually over time by chemical reactions such as hydrolysis. These sutures are ultimately converted to soluble components that are then metabolized and excreted ia urine or feces, or as carbon dioxide ia expired air. Absorbable sutures are iadicated only where temporary wound support is needed. 

Ascorbic acid is involved in carnitine biosynthesis. Carnitine (y-amino-P-hydroxybutyric acid, trimethylbetaine) (30) is a component of heart muscle, skeletal tissue, Uver and other tissues. It is involved in the transport of fatty acids into mitochondria, where they are oxidized to provide energy for the ceU and animal. It is synthesized in animals from lysine and methionine by two hydroxylases, both containing ferrous iron and L-ascorbic acid. Ascorbic acid donates electrons to the enzymes involved in the metabohsm of L-tyrosine, cholesterol, and histamine (128). 

There are two distinct groups of aldolases. Type I aldolases, found in higher plants and animals, require no metal cofactor and catalyze aldol addition via Schiff base formation between the lysiae S-amino group of the enzyme and a carbonyl group of the substrate. Class II aldolases are found primarily ia microorganisms and utilize a divalent ziac to activate the electrophilic component of the reaction. The most studied aldolases are fmctose-1,6-diphosphate (FDP) enzymes from rabbit muscle, rabbit muscle adolase (RAMA), and a Zn " -containing aldolase from E. coli. In vivo these enzymes catalyze the reversible reaction of D-glyceraldehyde-3-phosphate [591-57-1] (G-3-P) and dihydroxyacetone phosphate [57-04-5] (DHAP). 

Proteins are macromolecules that play many roles such as serving as enzymes or components of cell membranes and muscle. The antibodies that protect against invasion by foreign substances are themselves proteins. There are twenty-odd amino acids found regularly in most naturally occurring proteins. Because of the great length of protein chains and the various sequences of amino acids, the theoretic number of possible proteins is astronomical. The amino acid sequence is referred to as the primaiy structure of a protein. The pol eptide... 

Rossmann suggested that the canyons form the binding site for the rhi-novirus receptor on the surface of the host cells. The receptor for the major group of rhinoviruses is an adhesion protein known as lCAM-1. Cryoelectron microscopic studies have since shown that ICAM-1 indeed binds at the canyon site. Such electron micrographs of single virus particles have a low resolution and details are not visible. However, it is possible to model components, whose structure is known to high resolution, into the electron microscope pictures and in this way obtain rather detailed information, an approach pioneered in studies of muscle proteins as described in Chapter 14. 

Certain proteins endow cells with unique capabilities for movement. Cell division, muscle contraction, and cell motility represent some of the ways in which cells execute motion. The contractile and motile proteins underlying these motions share a common property they are filamentous or polymerize to form filaments. Examples include actin and myosin, the filamentous proteins forming the contractile systems of cells, and tubulin, the major component of microtubules (the filaments involved in the mitotic spindle of cell division as well as in flagella and cilia). Another class of proteins involved in movement includes dynein and kinesin, so-called motor proteins that drive the movement of vesicles, granules, and organelles along microtubules serving as established cytoskeletal tracks. ... 

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