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Biomedical subjects

G Barone

Publications and source records attributed to G Barone.

At least 55 records · Page 3Linked to original sources
PubMed1996

Temperature-induced denaturation of beta-glycosidase from the archaeon Sulfolobus solfataricus.

The beta-glycosidase isolated from the extreme thermophilic archaeon Sulfolobus solfataricus, grown at 87 degrees C, is a tetrameric protein with a molecular mass of 240 kDa. This enzyme is barely active at 30 degrees C and has optimal activity, over 95 degrees C, at pH 6.5. Its thermal stability was investigated at pH 10.1 and 10.6 by means of functional studies, circular dichroism and differential scanning calorimetry. There was no evidence of thermal activation of the enzyme and the temperature-induced denaturation was irreversible and not well represented by the two-state transition model. A more complex process occurred, involving the dissociation and unfolding of subunits, and subsequent nonspecific association and/or aggregation. Denaturation temperature was around 85 degrees C, depending on protein concentration. The denaturation enthalpy change was between 7,500 and 9,800 kJ.mol-1, depending on the pH. The collapse of the native structure around 85 degrees C was confirmed by circular dichroism measurements and time-dependent activity studies. Finally, preliminary investigations were performed on the recombinant enzyme expressed in Escherichia coli.

Calorimetry, Differential Scanning↗
PubMed1996

Gamma Knife radiosurgery for intracranial metastases: from local tumor control to increased survival.

We have analyzed a series of 225 patients with intracranial metastases (343 lesions), treated in our department by Gamma Knife radiosurgery over a 30-month period. We have used a modified Pittsburgh protocol and performed 242 procedures on 164 single/78 multiple lesions. Primary tumors were mostly carcinomas of the lung (52%) and breast (11.6%). Neuroradiological localization of the target was usually performed by stereotactic computed tomography. Magnetic resonance imaging was only used in special circumstances. Routine dose planning was assisted by three-dimensional reconstruction programs. Mean tumor volume was larger than expected (5.7 ml). Mean prescription dose and average dose were 21.1 and 29.9 Gy, respectively. Middle- and long-term results were evaluated in a subset of 152 patients (236 lesions) with adequate (> 4 months) follow-up. Mean follow-up was 53.1 weeks with 61/152 patients still living. There was a predominance of retrospectively classified 'not fully eligible cases' among the survivors, mainly because of uncontrolled primary tumor. The 1-year local tumor control rate was 88.2%. Treatment-related radiological (3.9%) and clinical (1.6%) sequelae were minimal. Overall mean survival in these patients (40 weeks) turned out to be higher than that commonly reported after conventional surgical-radiation treatments. It was encouraging that the mean survival of 'fully' eligible patients was 51 weeks. Karnofsky performance status and neurological (Order Grading) performance scores were consistently high for most of the follow-up period. Functional Independence and the Palliative Index were not far from the value of mean survival. The main cause of death remains uncontrolled systemic disease (64.8%). On the other hand, the relative incidence of intracranial tumor progression was considerably decreased. This indicated that these patients should perhaps be treated more aggressively and underlines the need for randomized trials to determine the optimal treatment.

Adult↗
PubMed1996

[Leiomyoma of the small intestines--a rare cause of emergency abdominal surgery].

The authors underline that, although rarely found, leiomyomas of the gastrointestinal tract are the most frequent benign tumours of the small intestine. On occasions, from being a simple autoptic finding or diagnosed during the course of explorative laparotomy, they may be responsible for emergency abdominal surgery, hemorrhage, occlusion or perforation. The authors discuss the experience acquired in two cases-treated during the last two years, both of which were symptomatic. In one case there was a palpable abdominal mass, and in both the key symptom was the appearance of melena a few days before being admitted to hospital. The most striking problem of this rare pathology is its diagnosis owing to both the absence of a specific clinical symptoms, and the difficulties shown in radiological diagnostics of the small intestine. In the authors' experience CAT using a contrast medium is an important instrument, whereas clyster of the small intestine is of scarce value. Explorative laparotomy was essential for removing any doubts regarding diagnosis. Both patients underwent extensive intestinal resection, including the mass and relative mesenteric wedge, with TT single-layer anastomosis. The postoperative period was normal.

Diagnosis, Differential↗
PubMed1995

The liquid amide transfer model and the unfolding thermodynamics of small globular proteins.

In this paper, the solid cyclic dipeptide model developed by Murphy and Gill is analysed in order to point out that, apart from general thermodynamic features shown by well-characterized small globular proteins, only the polar and apolar contributions to the net denaturation heat capacity change are necessary to calculate the so-called protein stability curve, delta dGzero versus temperature. We propose that these specific heat capacity contributions can be determined in a reliable manner by a group additivity analysis of the transfer process of liquid amides from pure liquid phase into water. This suggests that the unfolding process, thought of as the transfer of amino acid residues from the protein 'core' to contact with water molecules, can be modelled based on the transfer process of organic amides. The reliability of the model is tested in comparison with literature data.

Amides↗
PubMed1994

Structural investigation of Ceratozamia spinosa mucilage.

The polysaccharide fraction from Ceratozamia spinosa appears to be made up mainly by a chemically homogeneous polysaccharide but with a wide range of molecular weight. By NMR and chemical degradative methods, it is shown to consist essentially of a backbone of alternate-->4)-beta-D-GlcpA-(1-->and-->2)-alpha-D-Manp-(1--> units. On the 4 position of the latter, beta-D-GlcpA residues are linked. End units of alpha-L-Araf, beta-D-Xylp, alpha-L-Rhap, and alpha-L-3-OMe-Rhap are linked to C-3 and/or C-4 positions of beta-D-GlcpA residues.

Adhesives↗
PubMed1994

Wound healing in forefoot amputations: the predictive value of toe pressure.

A retrospective study of 136 men undergoing forefoot amputation was done to test the hypothesis that preoperative toe pressure (TP) could predict the likelihood of wound healing. Demographic data included age, smoking history, diabetes mellitus (DM), hypertension, hyperlipidemia, and coronary artery disease. Clinical data included infection, preoperative arterial Doppler data, TP, wound disposition, concomitant revascularization (REV), and healing outcome. Among diabetics, no primary amputation healed with a preoperative TP < 38 mm Hg. Among REV diabetics, no healing occurred with a TP < 40 mm Hg after bypass, but no failures occurred either with a TP > 68 mm Hg or an increase in TP > or = 30 mm Hg after bypass. Nondiabetic patients exhibited no threshold TP values. Univariate analysis revealed that DM and REV were significantly different in the healed (N = 83) vs. nonhealed (N = 53) populations (p = 0.027 and 0.034). In healed patients mean TP (71.8 +/- 3.5 mm Hg SEM) was significantly higher than in nonhealed patients (45.1 +/- 4.3 mm Hg SEM, p = 0.000). Logistic regression analysis identified age > 60 years (p = 0.03), DM (p = 0.003), preoperative TP (p < 0.001), and REV (p < 0.001) as significant independent predictors of forefoot amputation healing. Healing probability was calculated and plotted vs. TP for subpopulations based on age, DM, and REV status for both primary forefoot amputation and amputation concomitant with bypass. In this study population, therefore, preoperative TP appeared to be a useful clinical tool for predicting the healing potential of both primary forefoot amputations and amputations plus concomitant bypass for any given patient.

Adult↗
PubMed1994

Hydration enthalpy of model peptides: N-acetyl amino acid amides.

Determination of hydration parameters for the solute-solvent interactions of model peptide molecules can provide quantitative information on the factors affecting the folding and stability of proteins in aqueous solutions. Standard hydration enthalpies are calculated by combination of the standard sublimation and solution enthalpy data, experimentally determined. The results for some N-acetyl amino acid amides, assumed as model for peptides, are reported and the trend of hydration enthalpies with increasing complexity of the model molecules is discussed on the basis of the group additivity method. Further the direct proportionality between hydration enthalpy and non-polar accessible surface area (ASA) of each amino acid residue is emphasized. Finally it is pointed out that there exists a convergence temperature for the enthalpy associated with the hydration process of these model compounds and its value TH* = 93 +/- 7 degrees C is close to that found for small globular proteins (i.e. TH* = 100 +/- 6 degrees C). This finding can give some insights to clarify the emergence of convergence behaviour in the unfolding process.

Amino Acids↗
PubMed1993

Nortriterpenoid oligoglycosides from Chionodoxa luciliae.

Six new oligoglycosides of eucosterol derivatives were isolated from the bulbs of Chionodoxa luciliae Bossis. A chemotaxonomical relationship based on glycoside and homoisoflavanone content is revealed for some Muscari, Bellevalia, Chionodoxa and Scilla species.

Carbohydrate Sequence↗
PubMed1993

[Captopril administration before thrombolysis in patients with an acute myocardial infarct: a pilot study of the short- and long-term effects].

Several experimental studies, carried out on animals and on isolated heart, showed that captopril can reduce the post-ischemic reperfusion injury. Our study was aimed at checking the effects of captopril before thrombolysis in acute myocardial infarction (AMI) and included 204 patients, hospitalized within 4 hours from the onset of symptoms. Patients were randomly subdivided into 2 groups: the first group (105 patients, Group A: pretreatment) received 6.25 mg captopril orally about 15 min before iv administration of urokinase (2 million), the second group (99 patients, Group B: late-treatment) received captopril about 3 days after thrombolytic treatment. Captopril doses were later increased in both groups according to blood pressure. All patients were subdivided according to the localization of infarction. One hundred and thirty-seven patients showed anterior AMI (70 from Group A and 67 from Group B); 67 patients showed inferior AMI (35 from Group A and 32 from Group B). Ventricular hyperkinetic arrhythmias (VHA) due to reperfusion were evaluated during the first 2 hours. Ventricular hyperkinetic arrhythmias occurred in 11.4% of patients with anterior AMI in Group A versus 38.8% in Group B (p < 0.001). CK peak normalization time in the group with anterior AMI was achieved after 58 +/- 2 hours in Group A versus 72 +/- 2 hours in Group B (p < 0.01). Late arrhythmias, > Lown's class 2 was found to occur in 15.7% of patients with anterior AMI of Group A versus 32.8% in Group B (p < 0.05), at predischarge Holter test. One hundred and nineteen patients underwent a hemodynamic test about 3 weeks after AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Captopril↗
PubMed1992

Captopril and glutathione before thrombolysis in acute myocardial infarction: a pilot study.

This study is aimed at checking whether treatment with glutathione (GL) and captopril (CA) before thrombolysis can further improve the protective effects of ACE-inhibitors in cases with anterior acute myocardial infarction (AMI). Ninety-eight double blind randomized patients (86 men and 12 women) showing symptoms of AMI anterior and undergoing thrombolytic treatment were admitted to our study and subdivided into 4 groups. Group A (25 pts) received thrombolytic treatment only, Group B (23 pts) received 3 g GL intravenously 15 min before thrombolysis and for 2 h thereafter, Group C (26 pts) received 6.25 mg CA orally 15 min before starting thrombolytic treatment, Group D (24 pts) received 3 g GL intravenously before thrombolysis and for 2 h thereafter, and captopril as well like group C. On the third day after AMI onset groups A and B received CA also. In all groups, the doses of CA were gradually increased according to blood pressure values. The following features were considered: a) the occurrence of early (within the first 2 h after thrombolysis) ventricular hyperkinetic arrhythmias; b) CK peak; c) the normalization time of CK peak (NT); d) the occurrence of late ventricular hyperkinetic arrhythmias (VHA) in the predischarge Holter test (Lown's class 2); e) ejection fraction (EF) being measured in 60 pts undergoing haemodynamic test. The results were an follows: Group A: VHA early 13/25, CK peak 1982 +/- 282; NT 71 +/- 2 h; Late VHA 8/25; EF 53.5 +/- 2.5% (16 pts). Group B: VHA early 11/23; CK peak 1917 +/- 242 U/l; NT 69 +/- 3 h; late VHA 7/23; EF 54.5 +/- 5.4% (14 pts). Group C: VHA early 4/26; CK peak 1671 +/- 266 U/l; NT 58 +/- 3 h; late VHA 5/26; EF 55.5 +/- 3% (16 pts). Group D: VHA early 3/24; CK peak 1463 +/- 201; NT 56 +/- 4 h; late VHA 5/24; EF 57.6 +/- 4% (14 pts).

Aged↗
PubMed1991

The relevance of anatomic and hemodynamic factors to a classification of cerebral arteriovenous malformations.

Potential prognostic anatomic and hemodynamic factors were evaluated in 248 patients with cerebral arteriovenous malformations (AVMs), all treated by direct microsurgical removal. The size of each AVM was calculated by its volume, obtained by the multiplication of the three AVM diameters by 0.52. A surgical classification of AVM location (in 11 groups) is proposed. Types of feeders and of drainage were classified as superficial or deep; the extent of the drainage system was classified according to a four-degree scale. The mean flow velocity in the main AVM feeder, detected using transcranial Doppler ultrasonography, was used as an indirect measure of AVM shunt flow in a small number of patients (n = 29). AVM volume was a very important prognostic factor: the incidence of hyperemic complications and the morbidity and mortality rate were significantly higher when the volume of the lesion was greater than 20 cm3 (P less than 0.0001 for hyperemic complications; P less than 0.001 for permanent morbidity and mortality). The incidence of hyperemic complications and the morbidity rate were higher in AVMs in rolandic, inferior limbic, and insular locations than in AVMs in other locations. As for other anatomic factors: a) the presence of deep feeders significantly increased the incidence of hyperemic complications, as well as the morbidity and mortality rate; b) the presence of deep drainage significantly increased permanent morbidity only; c) the extension of the venous system was significantly related to the development of hyperemic complications, and to morbidity and mortality. Transcranial Doppler examination showed that mean flow velocities greater than 120 cm/s in the main feeder were associated with a significantly higher rate of postoperative hematomas and transient deficits. A classification of cerebral AVMs that takes into account AVM volume and location, the type of feeders, the extent of the drainage system, and the main feeder flow velocity is suggested.

Adolescent↗
PubMed1991

Treatment of cerebral arteriovenous malformations with a combination of preoperative embolization and surgery.

Forty-nine patients with cerebral arteriovenous malformations (AVMs) were treated with preoperative embolization followed by resection using a microsurgical approach. In 27 patients, the AVM was located in an eloquent area; in 32 patients, the volume of the AVM was over 20 cm3. Preoperatively, flow-directed embolization was performed in 10 patients (28 procedures), selective embolization with threads was performed in 35 patients (46 procedures), and a combination of flow-directed and selective embolization was performed in 4 patients (12 procedures). The percentage of reduction of the AVM volume averaged 36% after embolization. Five minor complications (transient neurological deficits, in 2 cases associated with ischemic areas on the CT scan) were observed after embolization. The interval between the last embolization and surgery was as follows: within 10 days in 7 patients; between 11 and 20 days in 3 patients; between 21 and 30 days in 10 patients; between 31 and 60 days in 11 patients; and 2 months later in 18 patients. The efficacy of this combined treatment (embolization plus surgery) was evaluated by the incidence of hyperemic complications and the clinical outcome. Hyperemic complications occurred more frequently in patients with an AVM volume greater than 20 cm3. When compared with flow-directed embolization, selective embolization was linked with decreased bleeding during surgery; postoperatively, the incidence of cerebral edema was also lower. Clinical outcome was better after selective embolization, with no occurrence of major deficits and no mortality. When the percentage of reduction of the AVM volume after embolization was 40% or more, the incidence of intraoperative hyperemic complications was lower; moreover, new permanent deficits were never observed in patients with this volume reduction. A retrospective clinical comparison of two groups of patients with similar AVM volumes (greater than 20 cm3)--those given combined treatment (n = 32) versus those treated by direct surgery alone (n = 27)--showed that intraoperative bleeding appeared to decrease in patients treated by embolization; the incidence of postoperative hyperemic complications was not different in the two groups. New major deficits and deaths were less frequent in patients treated by embolization (P = 0.05 for the incidence of major deficits); postoperative epilepsy was also less common in these patients. In conclusion, combined treatment with selective preoperative embolization and direct surgery may help the neurosurgeon in the treatment of large, high-flow AVMs, reducing the risks connected with their surgical removal.

Adolescent↗
PubMed1991

Use of a tunneling device to aid in positioning of a graft.

A tunneling device can be used to ensure easy placement of a prosthetic or autogenous graft. This can be done without the danger of the graft twisting, kinking or having the clips and ties pulled off. The often frustrating problem of ensuring that the arterial graft lies properly in position can be greatly simplified with the use of this technique.

Anastomosis, Surgical↗
PubMed1990

[Changes in the thyroid function during treatment of psychiatric disorders using lithium salts].

Lithium, a monovalent cation used mainly in the management of certain psychiatric disorders, appears to act on thyroid function and to interfere with T3 and T4 secretion. The authors have followed 10 patients treated with lithium salts for two years and have monitored some parameters of thyroid function. Clinical and laboratory signs of hypothyroidism appeared in one case and subsided after withdrawal of lithium treatment.

Adult↗
PubMed1990

Efficacy of captopril before thrombolysis in acute myocardial infarction: preliminary findings.

Studies on experimental animals indicate that ACE-inhibition might play an important role in coronary flow regulation and reperfusion damage limitation by alleviating non-irreversible myocardial damage and reducing Hyperkinetic Ventricular Arrhythmias (HVA) caused by reperfusion. This suggests the usefulness of captopril, an ACE-inhibitor containing the -SH group, in combination with systemic thrombolysis or mechanical revascularisation. The study was performed on seventy-two patients admitted to the hospital within 4 h of the onset of major cardiac symptoms due to Unstable Angina Pectoris (UAP) or Acute Myocardial Infarction (AMI). They were randomized either to treatment with oral captopril 15 min before thrombolysis (thirty-seven patients), or to thrombolysis followed by oral captopril on day 3-4 (thirty-five patients). In the early captopril-treated patients, a significant reduction in early arrhythmias was observed within 2 h, a lower incidence of late arrhythmias and a faster normalisation of necrosis enzymes. These data provide further evidence for the useful role of early captopril treatment in acute myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1990

Our experience in the management of pancreatic pseudocysts.

The authors discuss the problems in the diagnosis and treatment of pancreatic pseudocysts; they emphasize the risk of complication. The authors discuss their personal experience in the treatment of 31 pancreatic pseudocysts using the different techniques, and the very good results they observed in their own series.

Cholangiopancreatography, Endoscopic Retrograde↗