Biomedical subjects

L D'Andrea

Publications and source records attributed to L D'Andrea.

At least 19 recordsLinked to original sources

PubMed1992

Adult criteria for obstructive sleep apnea do not identify children with serious obstruction.

Although obstructive sleep apnea (OSA) occurs in the pediatric population, diagnostic criteria have not been established. Since criteria for adult OSA are well established, we asked whether commonly used adult criteria, such as the apnea index (based on the number of obstructive apnea [OA] events per hour), would identify children with serious sleep-related upper airway obstruction. Polysomnographic data were analyzed from 20 children (ages 8 months to 16 yr) with clinical evidence of upper airway obstruction during sleep (loud snoring and labored breathing) and who had cyclic oscillations of oxyhemoglobin saturation (SaO2) during sleep. The overnight studies included sleep state (EEG, EOG, and EMG), SaO2, ECG, nasal (end-tidal CO2) and oral (thermistor) airflow, chest and abdominal movement (inductance plethysmography), and video camera and behavioral observations. Measurements included the number of obstructive events > or = 10 s, the number of desaturations (> or = 5% decrease lasting > or = 5 s), the number of desaturation episodes to < 90%, < 85%, and < 80% lasting > 5 s, and the percentage of sleep time with SaO2 values < 90%. Gas exchange was impaired as evidenced by cyclic decreases in SaO2 and elevated PETCO2 values (maximum value 58 +/- 6 mm Hg). The children experienced 175 +/- 168 (range 6 to 609) episodes of decreased SaO2 > 5%, with an average minimum SaO2 of 66 +/- 13% (range 30 to 85%). The average number of apnea events was only 1.9 +/- 3.2 events/h (range 0 to 10.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

An interrupter technique for measuring respiratory mechanics and the pressure generated by respiratory muscles during partial ventilatory support.

We evaluated the airway occlusion maneuver as a method to estimate respiratory resistance, respiratory elastance and the pressure generated by respiratory muscles in ICU patients breathing in the PSV mode. The airflow was interrupted at selected flows or volumes during inspiration by a computer-driven rapid occlusion pneumatic valve. The airway occlusion was maintained for 2 to 3 s. From the airway pressure tracing we obtained various measurements of pressure. We then computed the pressure generated by the patient's inspiratory muscles. The method was validated by two different approaches in two groups of patients: the Pes and the CMV protocols. We conclude that the airflow interruption method can be used to measure basic respiratory mechanical parameters in PSV patients. The method also offers an opportunity to evaluate Pmusc,aw and the respiratory work performed by the patient.

Adolescent↗

PubMed1991

Isolation and localization of a spectrin-like protein from echinoderm sperm.

Thyone sperm undergo an explosive acrosome reaction resulting in the extension of a 90 microns long acrosomal process. In unreacted sperm, profilamentous actin is sequestered within the profilactin cup (Tilney: Journal of Cell Biology 69:73-89 1976), which consists of four major polypeptides: actin, profilin, and a 250/235 kDa equimolar doublet (TS 250/235). Dialysis of profilactin preparations into an actin assembly buffer resulted in the formation of acrosomal-like macromolecular aggregates containing actin, TS 250/235, and several other polypeptides as detected by SDS-PAGE. TS 250/235 was purified by subjecting extracts of pH solubilized profilactin cups to DEAE and phosphocellulose ion exchange chromatography. TS 250/235 demonstrated immunocrossreactivity with affinity purified polyclonal antibodies raised against S. purpuratus egg spectrin. As determined by biotinylated-calmodulin overlays, both subunits of TS 250/235 bound calmodulin in a Ca(++)-sensitive manner. Electron microscopy of low angle, rotary shadowed replicas of TS 250/235 revealed an elongate rod-shaped molecule with an average contour length of 203 nm. By indirect immunofluorescence, TS 250/235 was found to be uniformly distributed throughout the profilactin cup of the unreacted sperm. This distribution of TS 250/235 correlated with the location of monomeric actin as determined by localization studies utilizing fluorescent-DNase-1. Upon sperm activation, the cellular distribution of TS 250/235 dramatically changed and was observed both along the length and at the base of the extended acrosomal process.

Acrosome↗

PubMed1991

Body position changes redistribute lung computed-tomographic density in patients with acute respiratory failure.

Ten patients with parenchymal acute respiratory failure (ARF) underwent computed tomography (CT) scans while in the supine and prone positions. At equal levels of positive end-expiratory pressure, the authors measured the changes of CT density in dorsal and ventral basilar lung regions induced by the change of position as well as alterations of gas exchange. The level of venous admixture did not change with body position. The CT scan image of each lung was fractionated into ten levels from dorsal to ventral, each constituting 10% of the lung height. After measuring each lung fraction, the volume, the average CT number, its frequency distribution, and the expected normal value, we computed the lung tissue mass, the excess tissue mass, and the fraction of normally inflated tissue (excess tissue mass = amount of "tissue," which includes edema, cells, and blood in excess of the expected normal value). We also estimated the superimposed hydrostatic pressure on each lung region. We found that the excess lung tissue mass is independent of position. However, in patients in the supine position, lung CT density increased and regional inflation decreased from ventral to dorsal, suggesting progressive deflation of gas-containing alveoli along the gravity gradient. A similar ventral-dorsal deflation pattern occurred within 10 min in patients in the prone position. We conclude that the lung in patients with ARF behaves like an elastic body with a diffusely increased mass; dependent lung regions are compressed by the pressure of overlying structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1991