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M Camici

Publications and source records attributed to M Camici.

At least 73 records · Page 4Linked to original sources
PubMed1984

Phosphorylation of rabbit liver glycogen synthase by multiple protein kinases.

Purified rabbit liver glycogen synthase was found to be a substrate for six different protein kinases: (i) cyclic AMP-dependent protein kinase, (ii) two Ca2+-stimulated protein kinases, phosphorylase kinase (from muscle) and a calmodulin-dependent glycogen synthase kinase, and (iii) three members of a Ca2+ and cyclic nucleotide independent class, PC0.7, FA/GSK-3, and casein kinase-1. Greatest inactivation accompanied phosphorylation by cyclic AMP-dependent protein kinase (to 0.5-0.7 phosphate/subunit, +/- glucose-6-P activity ratio reduced from approximately 1 to 0.6) or FA/GSK-3 (to approximately 1 phosphate/subunit, activity ratio, 0.46). Phosphorylation by the combination FA/GSK-3 plus PC0.7 was synergistic, and more extensive inactivation was achieved. The phosphorylation reactions just described caused significant reductions in the Vmax of the glycogen synthase with little effect on the S0.5 (substrate concentration corresponding to Vmax/2). Phosphorylase kinase achieved a lesser inactivation, to an activity ratio of 0.75 at 0.6 phosphate/subunit. PC0.7 acting alone, casein kinase-1, and the calmodulin-dependent protein kinase did not cause inactivation of liver glycogen synthase with the conditions used. Analysis of CNBr fragments of phosphorylated glycogen synthase indicated that the phosphate was distributed primarily between two polypeptides, with apparent Mr = 12,300 (CB-I) and 16,000-17,000 (CB-II). PC0.7 and casein kinase-1 displayed a decided specificity for CB-II, and the calmodulin-dependent protein kinase was specific for CB-I. The other protein kinases were able, to some extent, to introduce phosphate into both CB-I and CB-II. Studies using limited proteolysis indicated that CB-II was located at a terminal region of the subunit. CB-I contains a minimum of one phosphorylation site and CB-II at least three sites. Liver glycogen synthase is therefore potentially subject to the same type of multisite regulation as skeletal muscle glycogen synthase although the muscle and liver enzymes display significant differences in both structural and kinetic properties.

Animals↗
PubMed1983

Multiple phosphorylation of rabbit skeletal muscle glycogen synthase. Evidence for interactions among phosphorylation sites and the resolution of electrophoretically distinct forms of the subunit.

Phosphorylation of rabbit skeletal muscle glycogen synthase by a cyclic nucleotide and Ca2+-independent protein kinase, PC0.7, caused the enzyme to be a better substrate for phosphorylation by another cyclic nucleotide and Ca2+-independent protein kinase, FA/GSK-3. In contrast, phosphorylation by the combination of FA/GSK-3 and cyclic AMP-dependent protein kinase led to less phosphorylation than predicted from the individual actions of the protein kinases. These results are explained in part by the existence of cooperative interactions among the phosphorylation sites of glycogen synthase. Phosphorylation by FA/GSK-3 also correlated with a reduction in the electrophoretic mobility, in the presence of sodium dodecyl sulfate, of the glycogen synthase subunit from an apparent molecular weight of 85,000-86,000 to values of 88,000 and ultimately 90,000. The synergistic phosphorylation by PC0.7 and FA/GSK-3 was associated with an increased formation of the species of reduced electrophoretic mobility. The effects on subunit mobility were also reflected in the behavior of a larger phosphorylated CNBr fragment of glycogen synthase, CB-2, which gave apparent molecular weights of 22,000-27,000 depending on its phosphorylation state.

Animals↗
PubMed1983

Prolonged plasma exchange in the treatment of renal involvement in essential mixed cryoglobulinemia.

Four men and 2 women with Essential Mixed Cryoglobulinemia and a membrano-proliferative glomerulonephritis were treated with prolonged Plasma Exchange without the addition of cytotoxic agents. All patients had Nephrotic Syndrome and Renal Insufficiency. Three of them presented a rapid deterioration of renal function just prior to Plasma Exchange treatment. Total number of procedures varied for each patients from 24 to 105. Serum creatinine decreased significantly in those patients with rapid deterioration of renal function, while it was not modified in the 3 with stable chronic renal failure. In no instance major side effects were recorded, and relapses of the disease did not occur, after gradually tapering of Plasma Exchange sessions. These data suggest that Plasma Exchange alone, if early instituted, may be an effective and safe treatment of Essential Mixed Cryoglobulinemia Glomerulonephritis.

Complement System Proteins↗
PubMed1982

Rabbit liver glycogen synthase. Susceptibility of the enzyme subunit to proteolysis.

Rabbit liver glycogen synthase have been purified close to apparent homogeneity in a form dependent on glucose-6-P for full activity. From analyses of the purified enzyme by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, some five polypeptides, apparent molecular weights in the range 79,000 to 90,000, correlated with enzyme activity. The relative abundance of the species varied in different preparations but enzyme could be prepared that was composed almost entirely of a 90,000-dalton polypeptide. Treatment of such enzyme with trypsin generated smaller polypeptides in the sequence 90,000 leads to 85,000 leads to 82,000 leads to 80,000; concomitantly, the enzyme was activated when assayed either in the presence or absence of glucose-6-P. Tryptic proteolysis caused as much as a 16-fold increase in Vmax and a 20-fold increase in the concentration of its substrate, UDP-glucose, necessary for half-maximal activity. The concentration of the activator, glucose-6-P, needed for half-maximal stimulation was decreased 3.5-fold. We propose that rabbit liver glycogen synthase in a glucose-6-P-dependent form has a subunit of apparent molecular weight approximately 90,000, larger than previously reported, and that the enzyme is sensitive to proteolytic degradation.

Animals↗
PubMed1982

Echocardiographic hemodynamic study during ultrafiltration sequential dialysis.

4 patients on regular dialysis were studied by the echocardiographic method during ultrafiltration and dialysis performed sequentially according to two different protocols. Blood pressure, heart rate, cardiac output, stroke volume, systolic and diastolic dimension of the left ventricle, systolic and diastolic volumes of the left ventricle, ejection fraction, shortening fraction and total peripheral vascular resistance index were measured. During ultrafiltration there is an increase of the total peripheral vascular resistance index. Myocardial contractility improves only during dialysis. Physiopathologic implications are discussed.

Adult↗
PubMed1982

Urinary excretion of oxalate in renal failure.

The daily urinary excretion of oxalate has been found to be lower than normal in patients with renal failure and the decrease to be directly proportional to the impairment of renal function. It has also been found that the gut flora from uremic patients destroys oxalate 'in vitro' more efficiently than the gut flora from normal people. It is postulated that an adaptation occurs in the gut flora of uremics to 'metabolize' oxalate, and this enteric elimination may account for its decreased urinary excretion.

Humans↗
PubMed1981

[Echocardiographic study of left ventricular function in 2 different procedures].

Four patients on regular dialysis were studied by echocardiographic method during ultrafiltration sequential dialysis performed according to two different protocols: procedure 1: ultrafiltration alone (1 hour) followed by diffusive dialysis (3 hours); procedure 2: dialysis (3 hours) followed by ultrafiltration alone (1 hour). Blood pressure, heart rate, cardiac output, stroke volume, systolic and diastolic dimension of the left ventricle, systolic and diastolic volumes of the left ventricle, ejection fraction, shortening fraction and total peripheral vascular resistance index were measured. During ultrafiltration there is an increase of the total peripheral vascular resistance index. Myocardial contractility improves only during dialysis. Physiographic and therapeutic implications are discussed.

Adult↗
PubMed1979

[Enzymologic characterization of adenosine nucleosidase of medicinal plants (Medicago sativa)].

Adenosine nucleosidase (adenosine ribohydrolase, E C 3.2.2.7) was purified from alfalfa leaf juice. The final preparation shows a single band on polyacrylamide gel electrophoresis; the enzyme activity is stable for 12 hrs between pH 5.5 and pH 8.5, but is completely lost on heating at 55 degrees C for 10 min. Optimal pH for the hydrolysis of adenosine is between pH 5 and pH 6. Among nine purine nucleosides tested, only adenosine, 2'-deoxyadenosine and purine riboside were hydrolyzed by the enzyme preparation. A Km value of 7 x 10(-6) M was found with adenosine as substrate at pH 7.4. Of the two reaction products, adenine exerted a weak inhibitory effect, while D-ribose was without effect on the initial rate of adenosine hydrolysis. The data reported are compared with those obtained on the enzymes from other plant sources.

Adenosine↗