Muscle studies

Upon the introduction of NMR proton relaxometry in muscle studies, it was early recognised that a model based only on dipolar interactions is far too simple,8 14 as ... 

Proton NMR spectroscopy ( H MRS) has shown to offer excellent possibilities for evaluation of biochemistry in vivo. Due to its non-invasive character it is of increasing interest not only for the study of human brain diseases, which describe the majority of clinical applications, but also for metabolic characterization of organs outside the brain, as prostate, liver, heart or skeletal muscle. Studies on skeletal muscle have been of increasing interest during the last years, since it was shown that MRS enables the differentiation between two muscular lipid compartments the bulk fat components along the fasciae and muscular boundaries, which are called extramyocellular lipids (EMCL), and the metabolically highly active intramyocellular lipids (IMCL). The latter are stored in spherical droplets in the cytoplasm of muscle... 

Tsien RW, Weingart R Inotropic effect of cyclic AMP in calf ventricular muscle studied by a cut end method. J Physiol (Lond) 1976 260 117-141. 

Subtype-selective agonists and antagonists of the adenosine receptors have been developed (Jacobson and Gao 2006). Table 13.1 shows the affinity at the human subtypes of selective ligand probes of the A, A2a, and A3 receptors used in skeletal muscle studies. Two agonists of the receptor are listed Cl-IBMECA is a 9-riboside... 

Myosin filament structure has been described by Squire et al. (2005). In vertebrate striated muscles the myosin filaments can be described approximately as three-stranded 9/1 helices. The helix pitch is 1287 A, but, because there are three strands and nine subunits in each strand, the structure repeats after C = 1287/3 = 429 A. Figure 12 shows the expected form of the low-angle diffraction pattern from such filaments. The modeling of this structure by X-ray diffraction was described by Squire et al. in terms of the three crowns of heads within each 429 A repeat. The crown repeat of 143 A gives rise to an m = +1 meridional reflection, which has been labeled as the M3 reflection in many muscle studies (as in Fig. 12). The myosin head array also gives rise to layer lines at orders of the repeat of 429 A. The first myosin layer line (ML1) is at 1/429 A-1, the second (ML2) at 2/429 = 1/ 214.5 A-1, and so on. The M3 reflection occurs on the third layer line at 3/429 = 1/143 A-1. 

Kress, M., Huxley, H. E., Faruqi, A. R., and Hendrix, J. (1986). Structural changes during activation of frog muscle studied by time-resolved X-ray diffraction./ Mol. Biol. 188, 325-342. 

Early study of bronchoconstricitive mechanisms of sulfur dioxide with ventilated, tracheostomized cats indicated that pulmonary resistance increased during the first breath but reversed rapidly (Nadel et al. 1965). Intravenous injection of atropine (a parasympathetic receptor blocker) or cooling of the cervical vagosympathetic nerves abolishes bronchoconstriction rewarming the nerve reestablishes the response. The rapidity of the response and its reversal emphasize the parasympathetically mediated tonal change in smooth muscle. Studies with human subjects have confirmed the predominance of parasympathetic mediation, but histamine from inflammatory cells could play a secondary role in the bronchoconstrictive responses of people with asthma (Sheppard et al. 1981). 

Bjork A, Hahdin M, Wahlin A. Enophthalmus elicited by succinylcholine some observations on the effect of succi-nylcholine and noradrenaline on the intraorbital muscles studied on man experimental animals. Acta Anaesthesiol Scand 1957 l(l-2) 41-53. 

Anabolic steroids decrease catabolism and increase skeletal muscle protein synthesis. Whether this results in muscular hypertrophy or hyperplasia, or a combination of these, is unclear and probably depends upon the muscle studied. Different muscle types contain different cytosolic receptor numbers and, therefore, the response to anabolic steroids varies. Anabolic steroids initiate an increase in RNA polymerase activity and the synthesis of either structural or contractile proteins. In some muscles, anabolic steroids may increase the ratio of fast twitch to slow twitch fibers (Nimmo et al 1982, Snow et al 1982). Increased activity of enzymes involved in energy metabolism may also occur. However, the total glycogen content may remain unchanged (Hyyppa et al 1997). The effects are most profound in females and castrated males (Snow 1993). 

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. 

In each section on the different ion channels, some unresolved issues and future directions will be addressed. In general, little is known about the precise molecular structures of the ion channels (e.g., K+ channels) in smooth muscle and our knowledge of endogenous agents as well as key signal transduction pathways that may modulate smooth muscle ion channels is far from complete. Further, as indicated previously, the modulation and expression of ion channels vary with the type of, and even within (e.g., large versus small arteries), smooth muscle. Studies on K+ channels in nonvascular types of smooth muscle will be discussed if similar material from arterial smooth muscle is limited. 

R. Cubeddu, G. Biscotti, A. Pifferi, P. Taroni, A. Torricelli, M. Ferrari, V. Quaresima, Functional muscle studies by dual-wavelength, 8-channel time-resolved oximetry, Proc. SPIE 5138, 29-34 (2003)... 

Westheimer, G. 1954. Mechanism of saccadic eye movements. AMA Archiv. Ophthalmol. 52 710-724. Wilkie, D.R. 1968. Muscle Studies in Biology, Vol. 11. Edward Arnold Ltd., London, United Kingdom. 

Despite the use of menthol in culinary and medicinal preparatitMis [2], relatively little is known about its actions on the human cardiovascular system, particularly in vascular smooth muscle. Studies in blood vessels evaluating the effects of menthol demonstrated different actions, particularly related to the precontractile state of the vasculature prior to menthol administration. 

Lewis RA, McDermott MP, Herrmann DN, Hoke A, Clawson LL, Siskind C, et al. Muscle Study Group. High-dosage ascorbic acid treatment in Charcot-Marie-Tooth disease type lA results of a randomized, double-masked, controlled trial. JAMA Neurol August 2013 70(8) 981-7. 

Dawson et al (1975, 1977) extended the P NMR technique to investigate the energetically important phosphate compounds of living muscle in different states, namely, rest, contraction, and recovery. They used the same 129 MHz spectrometer used by the Oxford group in their original muscle studies. They emphasized the desirability of measuring function as well as the spectrum in different physiological states. The major problem that had... 

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