Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe two siblings with distal myopathy with rimmed vacuoles, who died suddenly presumably due to fatal arrhythmia. Case 1. A 26-year-old man with a 4 year-history of progressive muscle weakness and wasting was hospitalized in April, 1989. The family history showed that his younger brother had the same disease, but his parents, not consanguineous, and other family members had no neuromuscular diseases. On admission, neurologic examination showed muscle weakness and atrophy in the distal portions of four extremities. No myotonia or fasciculation was present. The deep tendon reflexes were absent except diminished bilateral PTR. Sensation and co-ordination were normal. The creatinine kinase (CK) level was moderately elevated to 691 IU/l, and the aldolase mildly to 6.9 IU/l. Normal laboratory values included serum electrolytes, glucose and thyroid function study. An ischemic forearm exercise test revealed a normal rise in serum lactate and pyruvate concentrations. The glucose response after glucagon was normal in the fasting state. An electrocardiogram and chest film were normal. An electromyogram revealed myopathic changes with mild neuropathic changes, including positive sharp waves and fibrillation potentials at rest. The muscle biopsy specimen from the left anterior tibial muscle showed scattered fibers with rimmed vacuoles and moderate variation in fiber size. Neither fiber necrosis nor inflammatory cellular infiltration was seen. Regenerating fiber was not present. An electron microscopic examination showed numerous lamellar bodies of various size. Nerve biopsy was normal. He was diagnosed as having distal myopathy with rimmed vacuoles. Muscle weakness progressed gradually over the next two years, but his general condition was good. He asked to receive the corticosteroid therapy, and rehospitalized.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Distal myopathy with rimmed vacuoles and sudden death--report of two siblings]. 826 2

The binding properties of hepatic aldolase (B) were determined in digitonin-permeabilized rat hepatocytes after the cells had been preincubated with either glycolytic or gluconeogenic substrates. In hepatocytes that had been preincubated in medium containing 5 mM glucose as sole carbohydrate substrate, binding of aldolase to the hepatocyte matrix was maximal at low KCl concentrations (20 mM) or bivalent cation concentrations (1 mM Mg2+) and half-maximal dissociation occurred at 50 mM KCl. Preincubation of hepatocytes (for 10-30 min) with glucose or mannose (10-40 mM), fructose, sorbitol, dihydroxyacetone or glycerol (1-10 mM), caused a leftward shift of the salt dissociation curve (maximum binding at 10 mM KCl; half-maximum dissociation at 35 mM KCl) but did not affect the proportion of bound enzyme at low or high KCl concentrations. Galactose and 2-deoxyglucose had no effect on aldolase binding. Inhibitors of glucokinase (mannoheptulose and glucosamine) suppressed the effects of glucose but not the effects of sorbitol, glycerol or dihydroxyacetone. Glucagon suppressed the effects of glucose, fructose and dihydroxyacetone but not glycerol. Poly(ethylene glycol) (PEG) (2-10%), added to the permeabilization medium, increased aldolase binding and caused a rightward shift in the salt dissociation curve. In the presence of PEG (6-8%), the effects of substrates on aldolase dissociation were shifted to higher salt concentrations (50-100 mM versus 35 mM KCl). The effects of substrates (added to the intact cell) on aldolase binding to the permeabilized cell could be mimicked by addition of the phosphorylated derivatives of these substrates to the permeabilized cell. Of the intermediates tested dihydroxyacetone phosphate and fructose 1,6-bisphosphate were the most effective at dissociating aldolase (A50 values of 20 microM and 40 microM respectively). Other effective intermediates in order of decreasing potency were fructose 1-phosphate, glycerol 3-phosphate, glucose 1,6-bisphosphate/fructose 2,6-bisphosphate. These results show that aldolase B binds to the hepatocyte matrix by a salt-dependent mechanism that is influenced by macromolecular crowding and metabolic intermediates. Maximum binding occurs when hepatocytes are incubated in the absence of glycolytic and gluconeogenic substrates and minimum binding occurs in the presence of substrates that are precursors of either fructose 1,6-bisphosphate or triose phosphates. Since the bound form of aldolase represents a kinetically less active state it is proposed that aldolase binding and dissociation may be a mechanism for buffering the concentrations of metabolic intermediates.
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PMID:Substrate modulation of aldolase B binding in hepatocytes. 861 43


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