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Biomedical subjects

M Rocco

Publications and source records attributed to M Rocco.

At least 55 records · Page 3Linked to original sources
PubMed1994

A new device to remove obstruction from endotracheal tubes during mechanical ventilation in critically ill patients.

OBJECTIVE: To evaluate the efficiency of a new device developed to remove obstructions from endotracheal tubes (ETT) in mechanically ventilated patients. DESIGN: Open study in mechanically ventilated sedated and paralyzed ICU patients. SETTING: General ICU and Laboratory of Respiratory Mechanics of the University of Rome "La Sapienza". PATIENTS: 8 consecutive unselected mechanically ventilated, critically ill patients in which a partial obstruction of ETT was suspected on the basis of an increase of the peak inspiratory pressure (> 20%) plus the difficult introduction of a standard suction catheter. INTERVENTIONS: Obstructions to ETT were removed with an experimental "obstruction remover" (OR) MEASUREMENTS: "In vivo" ETT airflow resistance (0.25; 0.5; 0.75; 11/s) was evaluated before and after use of the OR; the work of breathing necessary to overcome ETT resistance (WOBett) was also evaluated before and after OR use. RESULTS: The use of OR significantly reduced in all patients the ETT "in vivo" resistance (From 5.5 +/- 2.3 to 2.9 +/- 0.5 cmH2O/l/s at 0.25 l/s, p < 0.05; from 9 +/- 2.4 to 3.8 +/- 0.8 cmH2O/l/s at 0.5 l/s; from 12.2 +/- 3.5 to 5.7 +/- 1.2 cmH2O/l/s at 0.75 l/s; from 16.9 +/- 6 to 9.3 +/- 3.8 cmH2O/l/s at 1 l/s, p < 0.01 respectively). Also the WOBett was significantly reduced after use of the OR (from 0.66 +/- 0.19 to 0.34 +/- 0.08 J/l; p < 0.05). CONCLUSION: this experimental device can be safely and successfully used to remove obstructions from the ETT lumen, without suspending mechanical ventilation, reducing the need for rapid ETT substitution in emergency and life-threatening situations.

Adult↗
PubMed1994

Structural basis of end-stage failure in ischemic cardiomyopathy in humans.

BACKGROUND: Ischemic cardiomyopathy is characterized by myocyte loss, reactive cellular hypertrophy, and ventricular scarring. However, the relative contribution of these tissue and cellular processes to late failure remains to be determined. METHODS AND RESULTS: Ten hearts were obtained from individuals undergoing cardiac transplantation as a result of chronic coronary artery disease in its terminal stage. An identical number of control hearts were collected at autopsy from patients who died from causes other than cardiovascular disease, and morphometric methodologies were applied to the analysis of the left and right ventricular myocardium. Left ventricular hypertrophy evaluated as a change in organ weight, aggregate myocyte mass, and myocyte cell volume per nucleus showed increases of 85%, 47%, and 103%, respectively. Corresponding increases in the right ventricle were 75%, 74%, and 112%. Myocyte loss, which accounted for 28% and 30% in the left and right ventricles, was responsible for the difference in the assessment of myocyte hypertrophy at the ventricular, tissue, and cellular levels. Left ventricular muscle cell hypertrophy was accomplished through a 16% and 51% increase in myocyte diameter and length, whereas right ventricular myocyte hypertrophy was the consequence of a 13% and 67% increase in these linear dimensions, respectively. Moreover, a 36% reduction in the number of myocytes included in the thickness of the left ventricular wall was found. Collagen accumulation in the form of segmental, replacement, and interstitial fibrosis comprised an average 28% and 13% of the left and right ventricular myocardia, respectively. The combination of cell loss and myocardial fibrosis, myocyte lengthening, and mural slippage of cells resulted in 4.6-fold expansion of left ventricular cavitary volume and a 56% reduction in the ventricular mass-to-chamber volume ratio. CONCLUSIONS: These results are consistent with the contention that both myocyte and collagen compartments participate in the development of decompensated eccentric ventricular hypertrophy in the cardiomyopathic heart of ischemic origin.

Cardiomyopathy, Dilated↗
PubMed1994

Effects of hyperbarism on central respiratory drive and respiratory pattern in humans.

The aim of our study was to evaluate the effects of increasing pressure (from 1 to 3 and 6 atm abs) on respiratory drive, respiratory pattern, and inspiratory impedance of the respiratory system. Seven healthy volunteers were studied during a dry compression to 6 atm abs in a hyperbaric multiplace chamber. We observed a significant increase in tidal volume, P0.1 (the pressure generated in the airway after 100 ms of inspiration against a closed inspiratory line), Ttot, and Ti, and a significant respiratory rate reduction with increasing pressure from 1 to 3 atm.abs; P0.1 also increased significantly when comparing 3 and 6 atm abs measurement with 1 atm abs. The P > 0.01 and P0.1/(VT/Ti) showed a significant progressive increase compared with 1 atm abs. In conclusion, the passage from 1 to 3 and 6 atm abs causes, in healthy subjects at rest, an increase in the central respiratory drive activity, evaluated with P0.1 measurement. The response to the respiration system is an increase in tidal volume and Ti with a decrease in respiratory rate.

Adult↗
PubMed1993

Dynamic light scattering studies of alpha IIb beta 3 solution conformation.

The prototypical integrin receptor, alpha IIb beta 3, isolated from the membrane fraction of human blood platelets by solubilization in Triton X-100 (reduced) and affinity chromatography on lentil lectin-agarose, has been further purified by gel filtration chromatography in octyl glucoside to obtain the intact receptor complex in a form suitable for hydrodynamic measurements. The molecular weight [(6.0 +/- 0.2) x 10(3)] and Stokes radius (2.3 +/- 0.1 nm) of detergent micelles formed in 0.03 M octyl glucoside have been determined by classical light scattering intensity and dynamic light scattering measurements, respectively. An algorithm has been developed which explicitly considers the contribution of detergent micelles to the intensity autocorrelation function of particles suspended in detergent. This procedure has been validated with polystyrene particles of known radius, as well as with the soluble protein fibrinogen. Application of these procedures to dynamic light scattering data obtained with alpha IIb beta 3 resulted in a translational diffusion coefficient (Dto(20,w)) of (2.78 +/- 0.31) x 10(-7) cm2 s-1, corresponding to a Strokes radius (Rs) of 7.67 +/- 0.85 nm for the integrin/octyl glucoside complex. Light scattering intensity measurements gave a molecular weight of (2.26 +/- 0.22) x 10(5) for the polypeptide moiety of the complex, in excellent agreement with the 2.28 x 10(5) value calculated from primary structure data. As a spherical, hydrated alpha IIb beta 3 complex, with bound detergent, would exhibit a Stokes radius of approximately 5 nm, these data indicate considerable asymmetry in the solution conformation of alpha IIb beta 3.

Chromatography, Gel↗
PubMed1993

Solution structure of human plasma fibronectin under different solvent conditions. Fluorescence energy transfer, circular dichroism and light-scattering studies.

Human plasma fibronectin is a high molecular weight (530,000), multi-domain, modular glycoprotein, consisting of two nearly identical subunits disulfide-bridged close to their C-terminal ends. Three sites that can be differentially labeled with fluorescent probes are present on each fibronectin subunit, the transglutaminase-sensitive Gln3 residue and the two free sulfhydryl residues, Cys1201 and Cys2196. These sites are located, respectively, in the N-terminal heparin/fibrin-binding domain, between the central DNA and cell-binding domains, and just before the C-terminal fibrin-binding domain. To map the relative spatial arrangement of these domains, steady-state and lifetime fluorescence energy transfer techniques were employed. Our results show that the minimal intramolecular distances between the labeled Gln3-Cys1201 and Gln3-Cys2196 pairs are 5.5(+/- 0.6) nm and 5.7(+/- 0.7) nm, respectively, as measured by steady-state methods. Lifetime methods gave somewhat higher distances of 8.1(+/- 0.2) nm and 7.6(+/- 0.2) nm, respectively, between these sites. The binding of heparin or subjection to high ionic strength had only a minor effect, while in the presence of 50% (w/v) glycerol, an increase of about 25% in the intramolecular distances between these sites was observed. A similar effect was induced by binding of fibronectin to the surface of Cytodex beads, an event which was previously shown instead to markedly increase the intersubunit distances between the Gln3-Gln3 and Cys1201-Cys1201 pairs. The solution structure of fibronectin was further investigated by elastic light-scattering and circular dichroism measurements. By elastic light-scattering, the radius of gyration of fibronectin was found to be 15.3(+/- 0.8) nm in the presence of 30% (w/v) glycerol, in contrast to a value of 8.6(+/- 0.3) nm under physiological conditions. Far and near ultraviolet circular dichroism spectra showed that only minor changes in the secondary structure of fibronectin take place on increasing the glycerol content of the solvent up to 34% (w/v). Our results complement previously available information on the solution structure of fibronectin and on its transition from the native compact conformation to a more expanded form on increasing ionic strength or glycerol content. In either situation, fibronectin seems to retain a basic structural core, in which the N-terminal, the central and the C-terminal regions of the two subunits strongly interact with each other. A major role of hydrophobic forces, in stabilizing the fibronectin conformations under these conditions, is therefore postulated. The transition to the extended forms seen in many electron micrographs can instead be explained by disruption of the proposed structural core upon adsorption to surfaces.

Circular Dichroism↗
PubMed1993

Intraoperative autotransfusion in hepatic resection for malignancy. Is it safe?

To evaluate whether intraoperative autologous transfusion increases the risk of hematogenous dissemination of tumor we reviewed the risk of lung metastasis as well as disease-free and long-term survival of patients who underwent resection of malignant hepatic neoplasms with this technique. A retrospective review of patients undergoing liver resection for malignant disease revealed 39 patients in whom intraoperative autologous transfusion was used. The 2-year actuarial survival in the patients in this series, as calculated with the Kaplan-Meier method, was predicted to be 75%. Two-year actuarial disease-free survival was predicted to be 28%, and the risk of developing lung metastasis at 3 years was estimated to be 40%. The predicted overall survival and risk of recurrence in this series compare favorably with published data for patients in whom intraoperative autologous transfusion was not used.

Actuarial Analysis↗
PubMed1993

Modeling the alpha IIb beta 3 integrin solution conformation.

The alpha IIb beta 3 platelet integrin is the prototypical member of a widely distributed class of transmembrane receptors formed by the noncovalent association of alpha and beta subunits. Electron microscopic (EM) images of the alpha IIb beta 3 complex show an asymmetric particle with a globular domain from which two extended regions protrude to contact the lipid bilayer. Distance constraints provided by disulfide bond patterns, epitope mapping, and ligand mimetic cross-linking studies rather suggest a somewhat more compact conformation for the alpha IIb beta 3 complex. We have studied the shape of detergent-solubilized alpha IIb beta 3 by employing a low-resolution modeling procedure in which each polypeptide has been represented as an array of interconnected, nonoverlapping spheres (beads) of various sizes. The number, size, and three-dimensional relationships among the beads were defined either solely by dimensions obtained from published EM images of integrin receptors (EM models, 21 beads), or solely by interdomain constraints derived from published biochemical data (biochemical model, 37 beads). Interestingly, although no EM data were employed in its construction, the resulting overall shape of the biochemical model was still compatible with the EM data. Both kinds of models were then evaluated for their calculated solution properties. The more elongated EM models have diffusion and sedimentation coefficients that differ, at best, by +2% and -18% from the experimental values, determined, respectively, in octyl glucoside and Triton X-100. On the other hand, the parameters calculated for the more compact biochemical model showed a more consistent agreement with experimental values, differing by -7% (octyl glucoside) to -6% (Triton X-100). Thus, it appears that using the biochemical constraints as a starting point has resulted in not only a more detailed model of the detergent-solubilized alpha IIb beta 3 complex, where the relative spatial location of specific domains the size of 5-10 kDa can be tentatively mapped, but in a model that can also reconcile the electron microscopy with the biochemical and the solution data.

Amino Acid Sequence↗
PubMed1993

Thrombocythemia and thrombosis of the adrenal vessels.

The authors describe a case of primary thrombocythemia and thrombosis of the adrenal vessels which they were able to examine by arteriography of the renal and adrenal arteries, by adrenal CT and at autopsy following the patient's death. The available research data and hypotheses concerning the pathogenesis of thrombosis and hemorrhage in thrombocythemia are reviewed, but the relationship between platelet number and function and the incidence of thrombotic and hemorrhagic complications has not yet been clearly established. Pathogenesis of thrombosis and hemorrhage in suprarenal vessels is not clear and the majority of authors postulate early venous damage.

Adrenal Glands↗
PubMed1992

Early prediction of successful weaning during pressure support ventilation in chronic obstructive pulmonary disease patients.

OBJECTIVE: The aim of this study was to examine variables for early prediction of successful weaning in chronic obstructive pulmonary disease (COPD) patients during pressure support ventilation weaning. DESIGN: Thirteen COPD patients were prospectively studied to compare the respiratory pattern (inspiratory time, expiratory time, total breath cycle duration, tidal volume, respiratory rate, minute ventilation), the respiratory drive (airway occlusion pressure at 0.1 sec, tidal volume/inspiratory time), and blood gases after 30 mins of pressure support weaning. SETTING: The study was performed in the 20-bed General Critical Care Unit of the Rome "La Sapienza" University Hospital. PATIENTS: We evaluated 13 consecutive COPD patients fulfilling the standard weaning criteria (including clinical status, blood gases, forced vital capacity, maximum inspiratory pressure, and spontaneous respiratory rate after a 30-min T-piece trial) in which we compared respiratory pattern, respiratory drive, and blood gases after 30 mins of pressure support weaning. MEASUREMENTS AND MAIN RESULTS: After 30 mins of pressure support ventilation weaning (pressure support level 20 cm H2O), we measured respiratory pattern (airway pressure and airflow tracing), airway occlusion pressure at 0.1 sec (occluding the inspiratory line during expiration with a rubber balloon), tidal volume/inspiratory time, maximal inspiratory pressure, and blood gases. According to the result of the weaning trial, the patients were divided into two groups (not weaned and weaned), and the statistical difference between the evaluated variables was analyzed in weaned and not weaned groups. We did not observe a significant difference in breathing pattern data and arterial blood gases between weaned and not weaned patients. By contrast, airway occlusion pressure at 0.1 sec and maximum inspiratory pressure measured after 30 mins of weaning trial appeared significantly (p less than .001) different in patients in whom the weaning trial succeeded or failed. Considering maximum inspiratory pressure, we could not separate weaned from not weaned patients, while all patients showing values of airway occlusion pressure at 0.1 sec less than 4.5 cm H2O were easily weaned. CONCLUSIONS: This study confirms that conventional weaning criteria are often inadequate in predicting successful weaning of COPD patients, while airway occlusion pressure at 0.1 sec during the first phase of pressure support ventilation weaning can represent a good weaning predictor.

Aged↗
PubMed1992

[Paroxysmal atrial arrhythmias in arrhythmogenic cardiomyopathy of the right ventricle with a familial character: the role of right atrial involvement].

Arrhythmogenic right ventricular cardiomyopathy presents a rather frequent familial occurrence. In the present study the cases of two brothers (25 and 30 years old, respectively) presenting with the peculiar finding of early involvement of right atrium, are described. Both subjects were investigated because of recurrent complex arrhythmias, including supraventricular (sustained atrial flutter, atrial tachycardia) and ventricular tachyarrhythmias (very frequent premature beats, nonsustained ventricular tachycardia). The associated echo-angiographic aspects of the right atrium and right ventricle were those typically described in arrhythmogenic right ventricular cardiomyopathy. The familial occurrence of simultaneous right atrial and ventricular involvement, to the best of our knowledge not previously described, can likely be due to the similar phenotypic expression of the same genotype. The prognostic significance of atrial involvement in right ventricular arrhythmogenic dysplasia is still to be defined and the clinical follow-up of these two cases may contribute to it.

Adult↗
PubMed1991

Ovarian leiomyoma. Case report.

We describe a case of primary ovarian leiomyoma in a 16 year old patient; both ovaries were affected. Since at intervention normal tissue was found, the left ovary was preserved and a 30-months follow-up was carried out. Tumour markers (CA-125; alpha-fetoprotein; CEA and beta-HCG) were tested. Such a case has not previously been reported. Etiopathogenesis is also discussed.

Adolescent↗
PubMed1990

Effects of the heat-moisture exchangers on dynamic hyperinflation of mechanically ventilated COPD patients.

In recent years the use of devices called Heat and Moisture Exchangers (HME) has become widespread as gas conditioners for ICU patients requiring mechanical ventilation. As an important variation of the resistive properties of the HME, related to flow and duration of use, has recently been pointed out during "in vitro" studies, the use of these devices in COPD patients could increase the levels of auto PEEP and dynamic hyperinflation. In this study we have compared the levels of auto PEEP and difference in functional residual capacity (delta FRC) in a group of COPD patients, requiring controlled mechanical ventilation (CMV), at basal conditions and after the insertion into the circuit of three HMEs (Dar Hygrobac, Pall Ultipor, Engstrom Edith) at random: the results obtained excluded a significant increase of auto PEEP and delta (FRC) both with "new" HMEs and after 12 h of continuous use.

Aged↗