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Biomedical subjects

A Sarti

Publications and source records attributed to A Sarti.

At least 19 recordsLinked to original sources
PubMed2002

Resistance to vecuronium in a term neonate.

We report a case of resistance to curarization in a term neonate undergoing surgery. The dosage of vecuronium required to obtain satisfactory muscular blockade and cessation of spontaneous breathing efforts was more than 10-fold the normal one. The operation was delayed for 90 min The mechanism of this marked resistance is unknown, but some possible hypotheses are presented, focusing on the neonate's poor intrauterine growth and an abnormality in pharmacodynamics.

Drug Resistance↗
PubMed2001

Left ventricular endocardial surface detection based on real-time 3D echocardiographic data.

OBJECTIVE: A new computerized semi-automatic method for left ventricular (LV) chamber segmentation is presented. METHODS: The LV is imaged by real-time three-dimensional echocardiography (RT3DE). The surface detection model, based on level set techniques, is applied to RT3DE data for image analysis. The modified level set partial differential equation we use is solved by applying numerical methods for conservation laws. The initial conditions are manually established on some slices of the entire volume. The solution obtained for each slice is a contour line corresponding with the boundary between LV cavity and LV endocardium. RESULTS: The mathematical model has been applied to sequences of frames of human hearts (volume range: 34-109 ml) imaged by 2D and reconstructed off-line and RT3DE data. Volume estimation obtained by this new semi-automatic method shows an excellent correlation with those obtained by manual tracing (r = 0.992). Dynamic change of LV volume during the cardiac cycle is also obtained. CONCLUSION: The volume estimation method is accurate; edge based segmentation, image completion and volume reconstruction can be accomplished. The visualization technique also allows to navigate into the reconstructed volume and to display any section of the volume.

Echocardiography, Three-Dimensional↗
PubMed2001

Influence of the liquid-phase mass transfer on the performance of a packed-bed bioreactor for wastewater treatment.

This paper reports on the influence of the liquid-phase mass transfer on the performance of a horizontal-flow, anaerobic, immobilized-biomass (HAIB) reactor treating low-strength wastewater. The HAIB reactor was subjected to liquid superficial velocities (vs) ranging from 10 to 50 cm h(-1), corresponding to hydraulic detention time (theta h) of 10-2 h. The best performance was achieved at an overall theta h of 3.3 h due to the interdependence of biochemical reactions and mass transfer mechanisms for process optimization. The HAIB reactor was provided with four intermediate sampling ports, and the values of v(s) were fixed to permit sampling at different ports corresponding to thetah of 2 h as vs increased. The chemical oxygen demand removal (COD) efficiencies increased from 68% to 82% with the increase of v(s) from 10 to 50 cm h(-1). It could be concluded that the performance of the HAIB reactor was improved significantly by increasing vs, thus decreasing the liquid-phase mass transfer resistance.

Bioreactors↗
PubMed2001

Glomerular permeability after surgical trauma in children: relationship between microalbuminuria and surgical stress score.

OBJECTIVES: To determine whether there is an increase of urinary albumin during and after surgical trauma and investigate a possible relationship between microalbuminuria and the severity of surgical stress. DESIGN: Prospective study. SETTING: University hospital pediatric intensive care unit. PATIENTS: Forty consecutive children scheduled for elective surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Microalbuminuria/urinary creatinine ratio (MACR) was measured before, during, and after elective moderate or major surgical procedures. The Oxford Surgical Stress Score (SSS) was determined for each patient at the end of the operation, and its relationship with maximum deviation of MACR from baseline values was investigated. MACR showed a progressive increase during surgery and a decrease afterward, reaching preoperative values in most cases within 24 hrs after the end of surgery. There was a significant correlation between the increase in MACR and severity of the surgical trauma as measured by SSS. Two patients showed a rise in MACR after the initial postoperative normalization before clinical appearance of a surgical complication and one patient showed a persistent rise in MACR before clinical appearance of a septic complication. None of the other patients showed any rise in MACR after postoperative normalization, and they all had an uneventful recovery. CONCLUSIONS: MACR rises during and after major or moderate elective surgery in children. There is a significant positive correlation between severity of surgical trauma and capillary permeability in pediatric patients. Microalbuminuria, as an index of capillary permeability, may be an early sign of incipient complications and assist in the identification of those patients whose condition will deteriorate. The test is a cheap, blood-sparing, easy-to-perform bedside procedure that may have a useful role in clinical practice for evaluating the effect of surgical trauma on capillary permeability in children.

Albuminuria↗
PubMed2001

[Prevalence of nosocomial infections in Intensive Care Units in Triveneto area, Italy].

BACKGROUND: Nosocomial infection is one of the most common complications affecting patients admitted in intensive care units (ICU). The aim of this study is to evaluate rates of ICU-acquired infections, potential risk factors for these infections, causative microorganisms and antibiotic resistance patterns. METHODS: A 1-day point-prevalence study was conducted in 39 ICUs in Triveneto area (Italy) in November 1998. The overall study population included 188 patients with mean age of 61.4+/-19.3 years; the mean SAPS II score at entry into the ICU was 44.4+/-16.8 and the median duration of hospitalization was 9 days (range 2-636). RESULTS: A total of 59 patients (31.4%) had 79 episodes of ICU-acquired infections; pneumonia (45.5%), bloodstream infection (30.4%), and urinary tract infection (11.4%) were the most frequent types of infection. The leading causative microorganisms were S. aureus (24.4%, 77% of them were resistant to methicillin), Enterobacteriaceae (24.4%), P. aeruginosa (23.2%), fungi (12.2%), coagulase-negative staphylococci (7.3%) and Enterococcus spp (4.9%). Independent risk factors for nosocomial infections were duration of hospitalization >7 days (OR 4.29, 95% CI 1.82-10.1), SAPS II score >30 (OR 3.34, 95% CI 1.0-11.18), total parenteral nutrition (OR 2.69, 95% CI 1.19-6.07) and tracheostomy (OR 1.88, 95% CI 0.84-4.20). CONCLUSIONS: Nosocomial infections are relatively frequent in Triveneto area ICUs. The predominance of pneumonia and bloodstream infection, and the high frequency of antibiotic-resistant pathogens indicate that resources had to be assigned towards the implementation of control programs of those infections, monitoring of antibiotic resistance and prescription, and antibiotic therapy guidelines.

Adolescent↗
PubMed2000

Subjective surfaces: a method for completing missing boundaries.

We present a model and algorithm for segmentation of images with missing boundaries. In many situations, the human visual system fills in missing gaps in edges and boundaries, building and completing information that is not present. This presents a considerable challenge in computer vision, since most algorithms attempt to exploit existing data. Completion models, which postulate how to construct missing data, are popular but are often trained and specific to particular images. In this paper, we take the following perspective: We consider a reference point within an image as given and then develop an algorithm that tries to build missing information on the basis of the given point of view and the available information as boundary data to the algorithm. We test the algorithm on some standard images, including the classical triangle of Kanizsa and low signal/noise ratio medical images.

Journal Article↗
PubMed2000

A geometric model for 3-D confocal image analysis.

In this paper, we use partial-differential-equation-based filtering as a preprocessing and post processing strategy for computer-aided cytology. We wish to accurately extract and classify the shapes of nuclei from confocal microscopy images, which is a prerequisite to an accurate quantitative intranuclear (genotypic and phenotypic) and internuclear (tissue structure) analysis of tissue and cultured specimens. First, we study the use of a geometry-driven edge-preserving image smoothing mechanism before nuclear segmentation. We show how this filter outperforms other widely-used filters in that it provides higher edge fidelity. Then we apply the same filter, with a different initial condition, to smooth nuclear surfaces and obtain sub-pixel accuracy. Finally we use another instance of the geometrical filter to correct for misinterpretations of the nuclear surface by the segmentation algorithm. Our prefiltering and post filtering nicely complements our initial segmentation strategy, in that it provides substantial and measurable improvement in the definition of the nuclear surfaces.

Algorithms↗
PubMed2000

Efficacy of hemodiafiltration in a child with severe lactic acidosis due to thiamine deficiency.

We report the case of a child in whom severe lactic acidosis (LA) and hyperammonemia developed after twenty days of total parenteral nutrition (TPN) for diffuse esophageal damage due to caustic ingestion. The revision of TPN preparation revealed that thiamine was never included and the hypothesis of thiamine deficiency was later confirmed measuring the serum thiamine level. Because severe metabolic acidosis the dialytic treatment with hemodiafiltration (HDF) and bicarbonate infusion were performed: the patient very quickly recovered with dramatic reestablishment of the acid-basic balance. Thiamine administration restored lactate metabolism. We emphasize that HDF is a useful and prompt treatment for LA to get over the critical phase of neurological and cardiological damage.

Acidosis, Lactic↗
PubMed1999

Regularization of blood motion fields by modified Navier-Stokes equations.

A technique for the regularization of incompressible fluid motion fields based on the use of modified Navier-Stokes equations is presented. It is shown that the technique belongs to the class of Tikhonov-type regularization methods. The technique was applied to an analytically known fluid-dynamic problem (Couette flow). Noisy and scattered versions of the analytical velocity field were generated, and the accuracy in reconstructing the analytical field was evaluated. It was found that accuracy depends on the value of a regularization parameter, and its optimal value depends on the entity of noise and scattering. When the optimal value is selected, the accuracy of the regularization technique is excellent, even for consistent noise and scattering levels. The technique was finally applied to echocardiographic data in order to estimate the blood velocity field within the left ventricle.

Algorithms↗
PubMed1999

Organ donation.

Explore the source record for details and available documents.

Adult↗
PubMed1999

Nonlinear multiscale analysis of three-dimensional echocardiographic sequences.

We introduce a new model for multiscale analysis of space-time echocardiographic sequences. The proposed nonlinear partial differential equation, representing the multiscale analysis, filters the sequence while keeping the space-time coherent structures. It combines the ideas of regularized Perona-Malik anisotropic diffusion and the Galilean invariant movie multiscale analysis of Alvarez, Guichard, Lions and Morel. A numerical method for solving the proposed partial differential equation is suggested and its stability is shown. Computational results on synthesized and real sequences are provided. A qualitative and quantitative evaluation of the accuracy of the method is presented.

Echocardiography, Three-Dimensional↗
PubMed1997

Formation of multinucleated giant cells in vitro is dependent on the stage of monocyte to macrophage maturation.

Multinucleated giant cells (MGC) are a common feature of granulomas that develop during various inflammatory reactions. MGC originate from fusion of monocytes or macrophages, but the exact mechanism of their generation is still unclear. In the present study, we investigated the influence of monocyte to macrophage maturation on the ability of human monocytes/macrophages to fuse with each other. MGC were generated in vitro by stimulation of human peripheral blood monocytes with cytokine containing supernatants. With freshly isolated monocytes, fusion rates of up to 90% were obtained. When monocyte to macrophage maturation was induced by culturing the cells in human serum, fusion rates gradually decreased with advancing time of the preceding culture (corresponding to the stage of differentiation) and almost no MGC formation could be obtained with 8-day-old macrophages. In contrast, fusion rates did not decrease when monocytes had been cultured under serum free conditions before stimulation. When freshly isolated monocytes were added to 1-week cultured macrophages, which had been membrane-labeled with a fluorochrome, fusion between the two populations could be induced. Because the ability for intracellular killing of certain pathogens is reduced in macrophages, fusion with monocytes (newly arriving at the site of inflammation) may represent an attempt to restore this capacity.

Cell Differentiation↗
PubMed1996

Arrhythmias and ischemia-like ECG changes in Reye's syndrome.

We report a fatal case of a child presenting Reye's syndrome associated with a variety of arrhythmias and ischemia-like ST-T ECG changes. At autopsy, fatty infiltration and patchy myocytolysis were detected in sections of the heart. This case report emphasizes cardiac involvement in Reye's syndrome and the possible mechanisms of arrhythmias in this disease.

Arrhythmias, Cardiac↗
PubMed1996

Evaluation of differential optical flow techniques on synthesized echo images.

The performance of three methods for evaluation of motion on synthesized 2-D echo image sequences with features similar to real ones are examined. The selected techniques based on the computation of optical flow are of the differential type and assume that the image brightness pattern is constant over time. They differ in the choice of the smoothing term and in the local or global treatment of the domain. The images were synthesized by simulating the process of echo formation, considering the interaction between ultrasonic fields and human tissues. Moreover, two different approaches were followed to generate the sequences: 1) a known motion field was applied to the intensity distribution of the synthesized images; 2) a known motion field was applied directly to the point scatterer distribution of the tissue. Favorable results were obtained by applying Lucas-Kanade and Horn-Schunck techniques to the sequences of the first type, while all the techniques produced large errors when applied to the other type of sequences. A discussion about the suitability of the above-mentioned techniques for evaluation of motion on real echocardiographic images is also presented together with some results.

Algorithms↗
PubMed1996

[Monitoring in pediatric anesthesia].

The monitor plan should be tailored to the individual patient, keeping in mind two main factors: the patient condition and the type of surgery to be performed. The advances in technology have greatly widened the scope of useful information to the physician, though direct contact and observation of the patient still remains the grounding of sound monitoring. In paediatric age the monitoring of breathing is of paramount importance since the high oxygen consumption-FRC oxygen supply ratio make children particularly prone to develop hypoxaemia very quickly. The minimal monitoring standard should include pulse oxymeter, a capnograph, an ECG monitor, oscillometer for noninvasive blood pressure measure and in the infant and young child a thermometer probe. For major surgery, in addition to mandatory monitoring many other physiological variables are checked frequently.

Anesthesia↗
PubMed1995

Cell membrane labeling with fluorescent dyes for the demonstration of cytokine-induced fusion between monocytes and tumor cells.

Fusion between monocytes and tumor cells has been suggested as a cause for tumor metastasis. The aim of the present study was to establish an in vitro fusion model representing the in vivo situation as close as possible. For this purpose fusion between cells was induced by cytokine containing conditioned medium. In order to prove that hybrid formation between tumor cells and monocytes occurs, a two-color-fusion-assay based on membrane labeling with the fluorochromes PKH 2 (green) and PKH 26 (red) was established. These fusion experiments were analyzed by microscopy and, in addition, by flow cytometry. The attempt to induce fusion between monocytes and several tumor cell lines of hematopoietic origin revealed quite diverse results. The most extensive hybrid formations were seen with TALL, a T-lymphocytic tumor line. The monocytic tumor line HL60 and the B-lymphocytic tumor line BL41 also clearly yielded hybrids with monocytes but in smaller numbers. With some other hematopoietic tumor lines no evidence for hybrid formation was detected. These studies indicate that fusion of normal monocytes with certain tumor cells may be induced under conditions that may occur in comparable manner in vivo.

Adult↗