Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Postoperative pulmonary complication and respiratory failure, frequently seen in undernourished patients such as those with esophageal cancer, were suspected to be due to respiratory muscle wasting caused by nutritional depletion. Based on this idea, the respiratory muscles obtained by biopsies during operation from diaphragm, external intercostal muscle, and rectus abdominis muscle were assessed histochemically in 32 patients. The specimens were stained for myosin ATPase to differentiate the types of muscle fibers, and then the size and distribution of the muscle fibers of each type were measured. In diaphragm muscle, cross-sectional areas of type 1 & 2 and the ratio of the area occupied by each fiber were usually the same; in external intercostal muscle, however, type 1 fibers were dominant and in rectus abdominis muscle, type 2 fibers were dominant. The cross-sectional area of each respiratory muscle fiber well correlated with certain anthropometrical indexes, and the nutritionally depleted cases, the muscle fibers were of a smaller size suggesting less respiratory muscle strength. The ratio of the area occupied by type 1 fibers in diaphragm muscle was linearly related to serum albumin, total cholesterol, and PNI (prognostic nutritional index). Type 2 fibers were dominant in malnourished patients, suggesting greater fatigue compared to well-nourished cases. Opposite findings were obtained in external intercostal muscle and rectus abdominis muscle, and the ratio of the area occupied by type 2 fibers was smaller in the undernourished cases, suggesting reduced maximum strength of these muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Histochemical analysis of respiratory muscles of patients with esophageal cancer--with special reference to the preoperative nutritional state]. 214 8

Increased maximum velocity of shortening (Vmax), increased shortening ability (delta Lmax) and decreased relaxation rate have been reported for arterial smooth muscle from 16- to 18-week-old spontaneously, hypertensive rats (SHR) compared with age-matched normotensive Wistar-Kyoto rats (WKY). Vmax is dependent on actomyosin ATPase activity, and this activity is in turn dependent on the level of phosphorylation of the 20-kDa myosin light chain (MLC20) normally a function of calcium concentration. In this article, methods are described and data are presented from studies addressing possible intracellular regulatory mechanisms that might lead to the altered contractility of the SHR arterial muscle. In one study, myofibrillar protein was extracted from 16- to 18-week-old SHR and WKY caudal arterial muscle. The Mg(2+)-activated ATPase activity was measured under conditions where the Ca2+ concentration was controlled. In another study, the amount of myosin present and relative proportions of the myosin heavy chain (MHC) isoforms were determined by quantitative SDS-PAGE using heavy molecular weight standards and bovine serum albumin as the standard for concentration. In a third study, MLC20 phosphorylation levels in electrically stimulated arterial muscle were determined by urea glycerol gel electrophoresis and Western blot analyses. The SHR (n = 6) myofibrillar ATPase liberated 0.011 +/- 0.003 mumol Pi/mg myosin/min, which was significantly more than the 0.006 +/- 0.001 mumol Pi/mg myosin/min liberated by the WKY (n = 4) myofibrillar ATPase (P < 0.05). Consistent with the increased ATPase activity, phosphorylation of MLC20 was increased by 2.8 times as much in the SHR compared with the WKY electrically stimulated arterial muscle. However, there was no difference in MHC isoform pattern in the SHR compared with the WKY arterial muscle in contrast to the findings of at least one other laboratory. This discrepancy is discussed. The data reviewed in this article lead to the conclusions that an increased actin-activated myosin ATPase activity and MLC20 phosphorylation are likely responsible for the increased velocity of shortening previously reported in SHR arterial muscle and the increased ATPase activity is not a function of an increased myosin content or of altered MHC isoform pattern in the SHR muscle.
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PMID:Arterial muscle myosin heavy chains and light chains in spontaneous hypertension. 918 11