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Biomedical subjects

G Barone

Publications and source records attributed to G Barone.

At least 73 records · Page 4Linked to original sources
PubMed1989

A calorimetric approach to the study of the interactions of cytidine-3'-phosphate with bovine seminal ribonuclease.

A calorimetric study at 25 degrees C is reported on the interaction between allosteric bovine seminal ribonuclease and cytidine-3'-phosphate. The results are compared with those obtained under identical experimental conditions for the interaction of pancreatic ribonuclease A and the same nucleotide. The analysis of the data provides evidence that the binding sites of seminal ribonuclease for cytidine-3'-phosphate are not equivalent, in agreement with previous equilibrium dialysis studies. A model with two sites with different affinities toward the nucleotide, the site with higher affinity resembling the binding site of pancreatic ribonuclease, is proposed. The values calculated for the thermodynamic parameters provide an insight of the forces involved in the interaction of the two enzymes with the nucleotide.

Animals↗
PubMed1989

Binding of lanthanum and gadolinium ions to concanavalin A studied calorimetrically at 25 degrees C.

The interaction between Concanavalin A (ConA) and the lanthanide ions La3+ and Gd3+ has been studied calorimetrically at 25 degrees C. The measurements were carried out at a pH of 4.5, where the protein exists prevailingly as a dimer. Calorimetry allows the direct determination of the binding enthalpy and the evaluation of both the apparent association constant, and the apparent free energy and entropy. Three groups of data were collected. The first concerns the interaction of the 'native' protein, i.e., fully metallized with Mn2+ and Ca2+, with the lanthanides. The second concerns the interaction of the completely demetallized protein with La3+ and Gd3+. Finally, the affinity of each complex was tested for the specific sugar alpha-methylmannopyranoside. The analysis of the thermodynamic parameters obtained, led to the following conclusions: 1) a specific site, named S3, exists on the protein for the lanthanides, distinct from the S1 site of the transition metal and from the S2 site, specific for calcium. There is only one S3 site per protomer when the protein has Mn2+ in S1 and Ca2+ in S2. Moreover, there is no appreciable competition for S1 and S2 from the lanthanides. The 'native' protein, metallized with La3+ or Gd3+, is a fully functional protein. 2) The demetallized protein (ApoCon A) has at least two sites per protomer for the lanthanides. The hypothesis is that, besides the S3 site, the lanthanides, in the absence of Mn2+, can also occupy the S1, but not the S2, site. The protein metallized only with gadolinium ion is completely inactive toward the interaction with the mannoside. The same happens when, along with gadolinium, only calcium or manganese is present. Hence, in the absence of the transition metal in S1 or of calcium in S2, the protein is not in the conformation suitable to interact with its specific substrate.

Binding Sites↗
PubMed1988

Emergency treatment of the complications of giant liver hemangiomas.

The authors discuss the problems of emergency treatment of cavernous hemangiomas of the liver. Five cases were observed and treated with different techniques, ligation of the hepatic artery, excision of the mass, embolization of the hepatic artery. The results of these procedures were strongly influenced by the patient's previous state. Treatment was successful in three patients, while the procedure adopted was able to stop the hemorrage in the other two patients. The physical state was very important for the prognosis; the two patients arriving at our Institute in deep shock both died.

Abdomen, Acute↗
PubMed1987

Protein-ligand interaction. A calorimetric study of the interaction of oligosaccharides and hen ovalbumin glycopeptides with concanavalin A.

A calorimetric study is reported concerning the interaction between concanavalin A (Con A) and some oligosaccharides and glycopeptides hydrolyzed from hen ovalbumin. The measurements were carried out in acetate buffer, pH 4.5, where, by far, the prevailing form of the protein is the dimeric one [Kalb, A.J., & Lustig, A. (1968) Biochim. Biophys. Acta 168, 366; Dani, M., Manca, F., & Rialdi, G. (1981) Biochim. Biophys. Acta 667, 108]. The calorimetric technique allows the direct determination of the binding enthalpy delta H, degrees B, the evaluation of the apparent association constant K'B, and then the evaluation of the apparent free energy and entropy, delta G degrees' B and delta S degrees' B. Three groups of data have been collected in the present study. The first one concerns the interaction between concanavalin A and some mono- and disaccharides [methyl alpha-glucopyranoside (alpha MGlup), methyl alpha-mannopyranoside (alpha MManp), D-maltose, D-trehalose, and D-cellobiose]. The analysis of the data indicates that in these cases there are small favorable entropic and enthalpic contributions to the affinity. The stoichiometry of the reaction is 2 mol of ligand/mol of Con A dimer, the sites resulting being equivalent and noninteracting. Melezitose, the only trisaccharide studied, shows a different behavior: its affinity for Con A is higher as compared to the other oligosaccharides containing alpha-glucosyl residues and closer to that of methyl alpha-mannopyranoside. However, the stoichiometry is different, namely, 1 mol of ligand/dimer of Con A.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Induction of procoagulant activity in human leukocytes with lipoglycans from mycoplasmas.

Lipoglycans from mycoplasmas possess the ability to induce the elaboration of procoagulant activity. This represents a third endotoxic property for these polymers, in addition to the pyrogenicity and clotting of Limulus lysate reported previously. Lipoglycans from three species of Acholeplasma (A. axanthum, A. granularum, and A. oculi) stimulated the elaboration in vitro of procoagulant activity by human mononuclear cells to differing extents. Two serotypes, 3 and 4, of Ureaplasma urealyticum also exhibited this stimulatory activity. The activities of lipoglycans tested were, in decreasing order, A. oculi greater than U. urealyticum type 4 greater than A. axanthum greater than U. urealyticum type 3 greater than A. granularum.

Acholeplasma↗
PubMed1986

Management of associated primary cerebral neoplasms and vascular malformations: 2. Intracranial arterio-venous malformations.

3 cases of primary cerebral tumours associated to intracranial arterio-venous malformations are reported. The presenting symptoms were caused by the AVM in 2 patients, by the tumour in 1 patient. In 2 cases the lesions were coexistent, while in one case the tumour was diagnosed 30 months after resection of the AVM. The tumour was a glioma in 2 cases, a pituitary adenoma in 1 case. The AVM was located in the right hemisphere in 2 patients, and was always ipsilateral to the tumour. Surgical treatment was undertaken in all patients, and consisted of resection of the tumour and AVM in 2 cases, and only resection of the tumour in 1 case. As regards outcome, one patient survived with a mild deficit, and 2 patients died from the natural evolution of the malignant tumour. It is concluded that the management of associated AVMs and brain tumours should be decided in the individual patient according to various considerations, owing to the variability of each lesion and to the relatively benign prognosis of an arterio-venous malformation.

Adenoma↗
PubMed1986

Management of associated primary cerebral neoplasms and vascular malformations: 1. Intracranial aneurysms.

18 patients harbouring a primary cerebral tumour associated with one or more intracranial aneurysms are presented. Initial symptoms were caused in 10 cases by the tumour, in 8 cases by aneurysmal rupture. In 2 cases the tumour was discovered years after the exclusion of the aneurysm. The tumour was supratentorial in 14 cases, and was more commonly a meningioma (44% of cases) or glioma (38% of cases). A total of 25 aneurysms were observed in the 18 patients: 8 had ruptured and 17 were incidental. The aneurysms were more commonly on the internal carotid artery (40%). Surgical treatment was undertaken in 13 patients, and consisted of: a) tumour resection plus aneurysmal exclusion in 6 patients, b) only tumour resection in 5 patients with incidental aneurysms, and c) only exclusion of the aneurysm in 2 patients later developing malignant gliomas. Rupture of incidental aneurysms was never observed. The prognosis was linked mainly to the nature of the tumour in cases with malignant tumours, and to the evolution of subarachnoid haemorrhage in patients with ruptured aneurysms. As a whole, a satisfactory recovery was observed in 7 patients, and death occurred in 11 patients, mainly due to progressive evolution of the malignant tumour (in 6 cases) or to fatal aneurysmal rebleeding (in 3 cases). It is concluded that tumours associated with aneurysms should be operated on at the same time whenever possible, and decisions regarding exclusion of incidental aneurysms should be balanced against the risks of the procedure.

Adult↗
PubMed1985

In vitro generation of procoagulant activity by Corynebacterium parvum-stimulated mononuclear leukocytes.

Thromboembolic complications are known in cancer patients after i.v. administration of Corynebacterium parvum. We examined the ability of this organism to induce production of procoagulant activity by human blood mononuclear leukocytes in vitro. After 4 hours incubation Corynebacterium parvum was an effective stimulant for mononuclear leukocytes, behaving in the same way as the typical gram-negative bacterium Escherichia coli, whereas mononuclear cells incubated with Staphylococcus aureus were not affected. Corynebacterium parvum used was found devoid of endotoxin by the Limulus assay and was not affected by Polymyxin B, which, on the contrary, inhibited Escherichia coli-induced production of procoagulant activity. Intact Corynebacterium parvum may be required for the production of procoagulant activity and, although this specific aspect of the research will require further study, from the exposed data it is concluded that such a production could be a factor contributing to the pathogenesis of the coagulopathy following Corynebacterium parvum therapy.

Blood Coagulation Tests↗
PubMed1983

A thermodynamic study of sperm-egg interaction.

We have studied the binding of spermatozoa to the receptor sites on the vitelline coat (VC) of glycerol-treated eggs (ghost eggs) of the Ascidian, Ciona intestinalis (Protochordate). Glycerol treatment cytolyses the egg without affecting the ability of the VC to bind spermatozoa in a species-specific manner; however, in this system binding is not followed by the acrosome reaction. The ghost eggs are metabolically inert. As a base line for our analysis, we have studied the concentration-dependent heat evolved and oxygen consumption of spermatozoa when diluted in sea water. The process has been analyzed on the basis of equations derived by Liquori and Tripiciano to describe cell growth. Upon binding to the ghost eggs, the spermatozoa produce an explosive heat evolution (excess heat) which is not accompanied by oxygen consumption. The excess heat produced plotted against sperm concentration (at constant egg concentrations) gives an asymmetric bell-shaped curve. This is interpreted as being due to the competitive effect of sperm agglutination at a high sperm concentration. It is concluded that only spermatozoa that attach singly (monomeric spermatozoa) to the egg undergo metabolic activation.

Animals↗
PubMed1982

Peptide-urea interaction. Heats of mixing of cyclic dipeptides with urea.

The excess enthalpies of the ternary aqueous solutions containing urea and the glycyl-glycine, glycyl-L-alanine, L-alanyl-L-alanine and sarcosyl-sarcosine diketopiperazines respectively have been determined. A weak but favourable enthalpic contribution to the interaction between these solutes is found. The difference between "strong" and "weak" interactions in aqueous solutions of non-electrolytes is stressed and the role of water in the weak, non-specific interactions, is discussed. The consequence of the weakness of the urea-peptide interactions on the binding of urea to the proteins is also briefly discussed.

Dipeptides↗