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Biomedical subjects

A Berti

Publications and source records attributed to A Berti.

At least 73 records · Page 4Linked to original sources
PubMed1987

Acylphosphatase levels of human erythrocytes during cell ageing.

Human erythrocytes contain an acylphosphatase isoenzyme, whose concentration during cell ageing was determined by an enzyme immunoassay. Erythrocytes were age-fractionated by isopycnic centrifugation in "Percoll" density gradients. Acylphosphatase concentration was found to rise with the increase of cell density. Maximum values were attained in the mature erythrocytes and there was only a slight decrease in the older cells. Acylphosphatase activity in human erythrocytes of different ages followed a similar pattern, a finding which was confirmed for rabbit red cells with different levels of reticulocytes. The most probable mechanism for the increase of acylphosphatase content and activity during red cell maturation appears to be a de novo synthesis of this enzyme during the reticulocyte stage and its storage, virtually unaffected, in the mature erythrocytes. The possible consequences of increased acylphosphatase levels on the metabolic modifications associated with erythrocyte ageing are discussed.

Acid Anhydride Hydrolases↗
PubMed1986

Balint syndrome: a case of simultanagnosia.

We describe a patient with a bilateral posterior lesion, who showed optic ataxia, gaze apraxia and the symptom which most authors call the inability to see more than one thing at a time. We discuss the last feature and the term simultanagnosia sometimes used to indicate it. Furthermore we stress the unusual localization of the lesion in this patient.

Aged↗
PubMed1986

Unilateral neglect: personal and extra-personal.

Ninety-seven right brain-damaged patients were given two tasks aimed at assessing unilateral neglect in personal and in extra-personal space. The frequency of the two aspects of neglect, as well as their patterns of association with each other and with more elementary neurological disorders are reported and discussed. The results suggest a non-unitary frame of spatial reference for unilateral neglect, which may tentatively be interpreted in terms of a personal vs extra-personal dichotomy.

Animals↗
PubMed1986

Unawareness of disease following lesions of the right hemisphere: anosognosia for hemiplegia and anosognosia for hemianopia.

Unawareness of motor and visual-field defects was investigated in 97 right brain-damaged subjects. Both kinds of anosognosia were found to be double-dissociated from more elementary neurological disorders and from personal and extra-personal neglect. The relationships between anosognosia and unilateral neglect are discussed and allusion is made to the implications concerning the neurological organization of higher control functions.

Adult↗
PubMed1986

Purification and characterization of rabbit muscle acylphosphatase in the thiol (-SH) form.

Modifications in the muscle acylphosphatase purification procedure enabled us to isolate the enzyme with its sole cysteine in the -SH form; this enzyme form is the most abundant in vivo. Our data demonstrates that the enzyme forms purified by previously reported procedures can be easily derived from a reaction of the SH-enzyme with oxidized glutathione. Probably most, or even all, of these enzyme forms are artifacts due to the purification. The SH-acylphosphatase shows kinetic parameters similar to those reported for the mixed disulfide with glutathione and S-S dimer, except for the specific activity value, which is about twice as much, and the Km, which is reduced.

Acid Anhydride Hydrolases↗
PubMed1985

Rabbit skeletal muscle acylphosphatase: the amino acid sequence of form Ra1.

Acylphosphatase was purified from rabbit skeletal muscle by a procedure involving an affinity chromatography step on immunoadsorbent and subsequent ion-exchange chromatography. Three molecular forms with acylphosphatase activity, named Ra1, Ra2, and Ra3, were purified and characterized with respect to molecular weight, amino acid composition, and main kinetic parameters. The amino acid sequence of Ra1 is given in the present paper. The Ra1 form consists of a single polypeptide chain of 98 amino acid residues and contains only one cysteine residue at position 21 that is S-S bound to glutathione. The polypeptide chain has an acetyl group blocking the NH2 terminus. Ra1, Ra2, and Ra3 are compared with the corresponding molecular forms isolated from skeletal muscle of horse and turkey.

Acid Anhydride Hydrolases↗
PubMed1985

Acylphosphatase from human skeletal muscle: purification, some properties and levels in normal and myopathic muscles.

Human skeletal muscle acylphosphatase was purified by immunoaffinity chromatography using anti-horse muscle acylphosphatase antibodies. The three forms of the enzyme present in human muscle are very similar to those found in muscles of other animal species. The two main forms, Hu 1 and Hu 3, were also characterized with respect to molecular weight and some kinetic properties. Levels of acylphosphatase activity were measured in specimens of muscle from normals and from patients with various forms of muscular dystrophies and other myopathies. Acylphosphatase activity appears to be lower in all myopathic forms considered than in controls, and seems to be correlated with percentage of Ca2+ activation of (Ca2+ + Mg2+)-ATPase.

Acid Anhydride Hydrolases↗
PubMed1984

Studies on synthesis and degradation rates and some molecular properties of guinea-pig muscle acylphosphatase.

Acylphosphatase (acylphosphate phosphohydrolase, EC 3.6.1.7) was purified from guinea-pig muscle by a procedure involving immuno-affinity chromatography and a subsequent ion-exchange chromatography. This purification technique gave an overall yield of about 60% and permitted the isolation of three molecular forms with acylphosphatase activity, with a distribution greatly resembling those found in horse and turkey muscle. The main form appears to be very similar to the corresponding form in horse and turkey muscle, as indicated by amino acid composition, end-group analysis, the presence of glutathione as a mixed disulphide in almost the same stoichiometric ratio and kinetic analysis. From turnover data, the main form of acylphosphatase in guinea-pig muscle exhibits a degradation constant of 0.10 day-1, corresponding to a half-life of 6.8 days. These values are very close to those found for muscle total soluble proteins.

Acid Anhydride Hydrolases↗
PubMed1984

Human skeletal muscle acylphosphatase: the primary structure.

Human skeletal muscle acylphosphatase, purified by a technique based on affinity chromatography on immunoadsorbent, has been sequenced completely using tryptic and peptic peptide series, prepared by reverse-phase high-pressure liquid chromatography. The sequence analysis was carried out on all the isolated tryptic peptides using a manual Edman degradation technique and time-course analysis of the released amino acids by carboxypeptidase A. The enzyme is NH2-blocked and the blocking group has been identified by fast atom bombardment mass spectrometry.

Acid Anhydride Hydrolases↗
PubMed1983

The primary structure of turkey muscle acylphosphatase.

The complete primary structure of turkey muscle acylphosphatase has been determined. The sequence was derived from peptides obtained by digestion of the carboxymethylated protein with pepsin and thermolysin and by subdigestion of some of the cyanogen bromide fragments with trypsin and Staphylococcus aureus protease. Peptides were purified by preparative finger prints and/or preparative high-performance liquid chromatography. Sequencing of the various peptides was achieved by manual Edman degradation and by time-course analysis of amino acids released by carboxypeptidases. The amino-terminal blocking group (acetyl) was determined by fast atom bombardment mass spectrometry. This sequence was compared with that of horse muscle enzyme determined previously.

Acid Anhydride Hydrolases↗
PubMed1983

Affinity chromatographic purification of horse muscle acylphosphatase: evidence of the existence of multiple molecular forms.

Acylphosphatase was purified from horse muscle by a new procedure involving an affinity chromatography step and subsequent ion-exchange chromatography. This procedure was considerably milder than the preceding one, gave an overall yield of about 60% of activity and permitted isolation of three molecular forms with acylphosphatase activity. All these enzymatic forms are tightly bound to Sepharose 4B-linked anti-horse muscle acylphosphatase antibodies. Two of these forms (Ho1 and Ho3) are present in larger amounts: Ho1 corresponds to the enzyme purified according to the older procedure; this enzyme is a mixed disulfide between a main chain of 98 amino acid residues and glutathione. Ho2 differs from Ho1 only in the chemical nature of the molecule(s) S-S bound to the sole cysteine present at position 21 of the main chain. Ho3 is an S-S dimer of the main polypeptide chain. Ho1, Ho2, and Ho3 elicit very similar kinetic parameters in the presence of benzoylphosphate as a substrate.

Acid Anhydride Hydrolases↗
PubMed1982

Purification of horse muscle acylphosphatase antibodies by affinity chromatography.

Horse muscle acylphosphatase antibodies were obtained by immunizing rabbits with the highly purified antigen cross-linked with glutaraldehyde. Specific antibodies were purified from the immunoglobulin fraction by affinity chromatography using a matrix coupled with the pure antigen as immunoadsorbent. The purified antibodies were partially characterized by immunodiffusion and immunoprecipitin techniques. These antibodies could be used to study aspects of the muscle acylphosphatase structure, localization and other biological properties.

Acid Anhydride Hydrolases↗
PubMed1979

Preparation and some properties of a dimeric form (S-S) of horse muscle acylphosphatase.

The use of sodium selenite as a catalyst in the presence of oxygen was a suitable technique to obtain in good yield an interchain S-S dimeric form of horse muscle acylphosphatase. The dimer so obtained possesses kinetic properties very similar to those of the native enzyme. On the other hand the dimer has shown a generally lower stability in respect of the thermal inactivation, particularly in the acidic environment, to the lyophilization and to the proteolytic attack. As regards the 8 M urea inactivation, the dimer is not able to completely regain its activity by dilution, showing a behaviour quite different from that of the native enzyme.

Acid Anhydride Hydrolases↗