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Biomedical subjects

A Accorsi

Publications and source records attributed to A Accorsi.

At least 19 recordsLinked to original sources
PubMed1992

Glucose 1,6-bisphosphate-overloaded erythrocytes: a strategy to investigate the metabolic role of the bisphosphate in red blood cells.

Human erythrocytes overloaded with glucose 1,6-bisphosphate were prepared in order to establish the metabolic significance of this phosphorylated sugar in the intact red cell. The intracellular glucose 1,6-bisphosphate concentration was increased six- and twofold over the normal level by encapsulating (i) the commercially available compound and (ii) the glucose 1,6-bisphosphate synthase obtained from rabbit skeletal muscle, respectively. In both experimental conditions, a reduction of glucose utilization by the loaded cells was observed after reequilibration to the steady state. At the steady state, the concentrations of the glycolytic intermediates and of the adenine nucleotides appeared substantially unmodified when compared with those of controls, with the exception of a 50% reduction of glucose and fructose 6-phosphate measured in erythrocytes encapsulated with exogenous glucose 1,6-bisphosphate. Under the considered experimental conditions, the elevated intracellular glucose 1,6-bisphosphate appears to display an inhibitory effect on hexokinase that overcomes the possible activation of phosphofructokinase or pyruvate kinase.

2,3-Diphosphoglycerate↗
PubMed1992

High resolution of multiple forms of red blood cell enzymes using a Toyopearl DEAE 650 S.

We have investigated a new anion exchange chromatographic support (Toyopearl DEAE 650 S) which simultaneously allows easily to remove hemoglobin from hemolysates and to obtain a very high resolution of enzymes present in multiple forms. The results obtained are better than those obtainable using an anion-exchange HPLC column. The data obtained at analytical level suggest a wider use of this new matrix also for preparative purposes without significant changes in the resolution.

Animals↗
PubMed1991

Cell age dependent decay of human erythrocytes glutathione S-transferase.

Human red blood cells contain both glutathione S-transferase sigma (GST sigma) and glutathione S-transferase rho (GST rho). While the first isozyme does not change in red blood cell fractions of different mean density (age), GST rho, the main isozyme, shows a pronounced cell age dependent decay. Ion-exchange chromatographic experiments show that GST rho consists of only one isozymic form in young erythrocytes but is present in two components, with different electric charge, in mature and old cells. The "secondary" GST rho isozyme is more heat stable than the "primary" GST rho isozyme with the result that the total GST activity shows an apparent increase in heat stability during cell aging due to the formation of "secondary" isozymes. The kinetic properties and specificity of this enzyme do not show appreciable modifications during cell ageing. The data reported in this paper suggest that red blood cell aging is associated with a reduced detoxifying ability due to GST rho decay.

Erythrocyte Aging↗
PubMed1991

Specificity of glucose 1,6-bisphosphate synthesis in rabbit skeletal muscle.

1. To compare glucose 1,6-bisphosphate synthesis in different types of cells, we partially purified (2000-fold) a glycerate 1,3 P2-dependent glucose 1,6-bisphosphate synthase from rabbit skeletal muscle. 2. In agreement with the results reported by others for mouse brain and pig skeletal muscle, the enzyme can be separated from bulk phosphoglucomutase (PGM) activity by DEAE-cellulose chromatography of crude cellular extract. This cannot be achieved on human hemolysates where glycerate 1,3-P2-dependent glucose 1,2-bisphosphate synthesis is displayed only by multifunctional PGM2 isoenzymes. 3. The Km values for glycerate 1,3-P2 (0.50 microM), glucose 1-phosphate (90 microM), Mg2+ (0.22 mM), and also pH optimum (7.8) and mol. wt (70,000) of the rabbit skeletal muscle enzyme are similar to those of the enzymes from mouse brain and human red blood cells, but they differ from those reported for the pig skeletal muscle enzyme.

Animals↗
PubMed1991

Omphaloplasty.

Two different omphaloplasty procedures are presented. The first procedure, resulting in a four-point, star-shaped navel and indicated for patients with classic abdominoplasties, aims at preventing widening of the navel, as well as stenosis, later on, postoperatively. The second procedure, based on the rotation of the remaining navel and indicated for both patients with midi or mini abdominoplasties and patients with secondary omphaloplasty, also aims at preventing stenosis and widening of the umbilical scar; however, no external scars remain after this procedure.

Bandages↗
PubMed1991

[Neurocysticercosis in childhood. I. Clinical and laboratory diagnosis].

Clinical and laboratory findings among 34 children (age range from 15 months to 13 years) with neurocysticercosis were reviewed. The main symptoms were: intracranial hypertension, 21 cases (62%); epilepsy, 20 cases (59%); hemiplegia, 4 cases (12%). Computed tomography (CT) in 33 children showed typical brain active cysts in 26 patients (79%) and calcifications in 2 (6%). The complement fixation reaction or the indirect immunofluorescent test for cysticercus antibody were positive in CSF in 77% (20 out of 26 patients) and serum in 78% (18 out of 23 patients). CSF pleocytosis was found in 57% of the cases (15/26 patients) with eosinophil cells in 27% (7/26 patients). The most efficient diagnostic test was CT scan of the head, and was confirmed immunologically by measurement of cysticercus antibody titers in CSF and serum.

Adolescent↗
PubMed1991

[Neurocysticercosis in childhood. II. Computed tomography of 24 patients according to symptomatic and praziquantel treatment].

We studied 24 children (15 months to 13 years old) which clinical, CSF and CT findings were compatible to the diagnosis of active neurocysticercosis. The patients were divided into three groups based on the type of treatment: Group I (10 patients) treated with analgesics and/or anticonvulsants; Group II (4 patients) treated with analgesics and or anticonvulsants and corticosteroids; Group III (10 patients) treated with analgesics and/or anticonvulsants, corticosteroids and praziquantel. The first patients CT scan were compared with the sequential CT scan findings (1 month to 5 years). The initial CT scan of 12 patients showed multiple active cysts, in 5 patients an isolated active cyst, in 3 patients partial calcified cysts, in 2 patients cerebral edema and in 2 patients were normal. The final results of the three groups of patients, as far as concern the normalization of CSF abnormalities or calcification of the cysts were the same, no matter the type of treatment applied to them. These results, although the small number of patients, showed that most of the children have good final results, with improvement of clinical symptoms and CT findings. We suggest that neurocysticercosis in children need multicenter study. So, a great number of patients can be followed and better definition can be established on the treatment of neurocysticercosis.

Adolescent↗
PubMed1991

Purine nucleoside phosphorylase from human erythrocytes: a kinetic study of the fully separated isoenzymes.

Human red cell lysates contain at least seven electrophoretically distinct isoenzymes of purine-nucleoside phosphorylase (PNPase); the proportion of more anodal bands increases as the erythrocyte ages, suggesting that the native enzyme is subjected to progressive post-translational modifications. The age dependent electrophoretic changes observed in the hemolysate are associated with the downward curvature of the Lineweaver-Burk double reciprocal plot at high inosine-substrate concentrations unlike the single-banded PNPase from tissue cultures of rapidly dividing cells. Thanks to the high resolution power of the ion-exchange HPLC technique utilized we have been able to fully separate all the seven isoenzymes and correlate structural to functional modifications in PNPase from human erythrocytes. Our results indicate that the downward curvature of Lineweaver-Burk plot is not due to a mixture of isoforms with low and high Km for inosine but that the allosteric activation by the inosine substrate is the direct consequence of structural modification(s) on the "primary" form of the enzyme.

Adult↗
PubMed1991

Human red blood cells as bioreactors for the inactivation of harmful xenobiotics.

Human red blood cells are able to inactivate lipophilic electrophiles by conjugation with reduced glutathione. This metabolic ability was found to be limited by the rate of permeation of the xenobiotic into erythrocytes and by the amount of available reduced glutathione. By a procedure of hypotonic dialysis, isotonic resealing and reannealing human red blood cells were overloaded with increasing amounts of reduced glutathione up to three- to fourfold the normal level without modification of their metabolic functions or of their energetic state. These overloaded erythrocytes were able to conjugate increasing amounts of xenobiotics and to export the resulting conjugates from the cells. These properties of glutathione overloaded erythrocytes are significant for the use of carrier erythrocytes in cases of acute intoxication by lipophilic electrophiles.

Biotechnology↗
PubMed1990

Purification and partial characterization of the phosphoglucomutase isozymes from human placenta.

We have developed a simple procedure for the purification of phosphoglucomutase (PGM) isozymes from human placenta of healthy women. The technique involves the ammonium sulfate fractionation, ion-exchange and dye-ligand chromatographies. By this method we obtained homogeneous isozyme preparations of the products ("primary" and "secondary") of the two PGM1 and PGM2 loci. The final specific activities were 1134.6-1441.8 units/mg for PGM1 forms and 40.2-46.5 units/mg for PGM2 forms. On SDS-polyacrylamide gel electrophoresis analysis, the final preparations gave a single protein band of 58,500 and 69,000 Mr for PGM1 and PGM2 isozymes, respectively. These forms have the same kinetic properties, but from the substrate specificity experiments we have found that PGM2 forms are more effective for catalyzing the phosphoribomutase and glucose 1,6-bisphosphate synthase reaction than PGM1 forms. All these properties are shared by the same isozymes previously isolated from human erythrocytes but in this procedure the use of human placenta for the PGM isozymes purification takes advantage of high specific activity of PGM in the extracts of this tissue as well as obtaining highly homogeneous protein suitable for studies at molecular level.

Adult↗
PubMed1990

Immunological studies on erythrocyte phosphoglucomutase isozymes.

Human erythrocytes (phenotype PGM1 a1 or PGM1 a3) contain two sets of phosphoglucomutase isozymes, produced by the expression of the PGM1 and and PGM2 loci. The two sets are constituted each by two forms, of which that called "secondary" is thought to derive from the post-translational modification of that called "primary". Cross-reactivities of these isozymes were studied by means of monospecific rabbit antibodies against purified human red cell PGM1 and PGM2 "primary" isozymes. The results show that the PGM1 and PGM2 forms are not immunologically related and provide further proof of the post-synthetic origin of "secondary" isozymes and of the multifunctionality of PGM2 phosphoglucomutases.

Antibodies↗
PubMed1989

Cell age dependent decay of human erythrocytes glucose-6-phosphate isomerase.

Glucose-6-phosphate isomerase shows a biphasic decay pattern during red blood cell aging, which is very fast during the first part of cell's life span in circulation. This decay is not due to accumulation of inactive enzyme molecules, as shown by immunological studies, but is accompanied by the formation of secondary isozymes (i.e., chemically modified forms). Electrophoretic and ion-exchange chromatographic experiments show that glucose-6-phosphate isomerase (D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) consists of only one isozymic form in young erythrocytes but is present in two components, with different electric charge, in mature and old cells. This secondary isozyme is more stable to heat treatment and is inactivated by IgG anti-glucose-6-phosphate isomerase with a lower affinity than the native isozyme. In vitro incubation of homogeneous human glucose-6-phosphate isomerase under conditions known to produce enzyme deamination does not reproduce the isozymic pattern found in erythrocytes, suggesting that one or more mechanisms other than those previously described to explain glucose-6-phosphate isomerase microheterogeneity occur in the human erythrocyte.

Chromatography↗
PubMed1989

Isoenzymes of phosphoglucomutase from human red blood cells: isolation and kinetic properties.

A procedure has been developed for the purification of phosphoglucomutase from human red cell (phenotype PGM1 a1 or a3) lysates. It yields homogeneous isoenzyme preparations of the products ("primary" and "secondary") of the two PGM1 and PGM2 loci with distinctive pI (from 6.07 to 5.29). There are substantial differences between PGM1 and PGM2 isoenzymes, having single polypeptide chains of 58,500 and 69,000 Mr respectively and showing different thermostability. The kinetic properties of all the isoenzymes for the phosphoglucomutase reaction are essentially the same (apart from the specific activity of 1089-1263 units/mg for PGM1 forms vs 37-42 units/mg for PGM2 forms), but there are striking differences in substrate specificity. In fact the products of PGM1 locus are "true" phosphoglucomutases, being specific to mutate glucose monophosphates, whereas the PGM2 forms also display phosphoribomutase and glucose 1,6-bisphosphate synthetic activities. Some kinetic properties of these "side activities" are also reported.

Chromatography, DEAE-Cellulose↗
PubMed1988

Simultaneous preparation from human placenta of several enzymes of glucose metabolism.

A procedure for the simultaneous purification to homogeneity of hexokinase, phosphoglucomutase 1 and 2, aldolase, phosphoglucose isomerase and glucose-6-phosphate dehydrogenase from human origin has been developed. Human placenta homogenate was first chromatographed on DE-52 column which retains hexokinase and glucose-6-phosphate dehydrogenase while the other enzymes are recovered in the unabsorbed protein fraction. The other steps in the purification involve Matrex gel and specific affinity chromatography for the DE-52 retained enzymes and phosphocellulose and Matrex gel chromatography for the other enzymes. All the enzymes mentioned were obtained in one week, with recoveries from 14 percent for glucose-6-phosphate dehydrogenase to 75 percent for hexokinase. Thus, the procedures utilized seem to be useful in obtaining large amounts of enzymes in a a homogeneous form from an easily available human tissue.

Chromatography, Affinity↗