Biomedical subjects

D Negrini

Publications and source records attributed to D Negrini.

43 records · Page 3Linked to original sources

PubMed1985

Regional protein absorption rates from the pleural cavity in dogs.

In five supine spontaneously breathing anesthetized dogs we injected into the pleural space 0.5-1 ml of saline solution containing 2 mg/ml albumin labeled with technetium-99m. By use of a gamma camera placed horizontally over the chest, we followed, up to 120 min, the activity over the whole lung and over the preferential accumulation areas of the label (regions of interest, ROI) that corresponded to the apical, mediastinal, and laterodiaphragmatic regions. Activities were corrected for the decay rate of the isotope used. On the average, the activity over the whole lung decreased by 27% up to 120 min. The overall activity over the ROI amounted to 44.3% after the injection and decreased to 24% of total at 120 min, thus accounting for 75% of the total decrease in activity. At 10 min, the activity per unit surface of the gamma camera image (As) was from 2.2- to 5.7-fold higher over the ROI than for the rest of the lung image. The decrease of As at 120 min was 18-, 13-, and 5-fold greater for mediastinal, diaphragmatic, and apical regions, respectively, compared with the rest of the lung image. The time course of the changes in As are discussed in terms of regional albumin egress rate based on the functional interaction between the Starling and the lymphatic mechanisms.

Absorption↗

PubMed1984

Pleural liquid pressure gradients and intrapleural distribution of injected bolus.

In supine anesthetized dogs we measured pleural liquid pressure (Pliq) in mediastinal, diaphragmatic, apical, and costal regions at different lung heights during eupneic breathing. At end expiration and at a given height, Pliq was similar in the costal and apical regions, but it was lower in the diaphragmatic and mediastinal compartments. Inspiratory swings toward lower values were progressively greater with increasing height and moving from costal to apical, diaphragmatic and mediastinal compartments. Thus during inspiration, at any height, the costomediastinal and costodiaphragmatic Pliq difference increased while a costoapical difference developed. One minute after injection of 0.5-1 ml of saline at different points within the cavity, end-expiratory liquid pressure became higher on the average by 0.45, 1.55, and 0.55 cmH2O in the apical, mediastinal, and diaphragmatic compartments, respectively, while no change was observed on costal side. These results suggested liquid accumulation in the compartments displaying a lower Pliq. This was confirmed by following, with a gamma camera, on a frontal projection of the lung, the intrapleural distribution of a bolus containing 99mTc-labeled albumin injected at various places.

Animals↗

PubMed1984

Comparative features of Starling-lymphatic interaction at the pleural level in mammals.

Pleural liquid pressure was measured with saline-filled cannulas in rats, rabbits, cats, pups (4-5 days and 2 mo), small and large dogs, and pigs. On both the costal and mediastinal sides pleural liquid pressure at a level corresponding to the tricuspid valve decreased with increasing body mass; because this behavior was more marked on the mediastinal than on the costal side, a horizontal costomediastinal pleural liquid pressure gradient developed. No differences in liquid pressure were found in animals of different age but of similar size. The protein concentration and the volume-to-body weight ratio of the collected pleural liquid were also found to decrease with increasing body mass. For plasma colloid osmotic pressure, no size-related differences in the Starling balance seem to occur on costal side, whereas such balance shifts toward filtration at mediastinal level with increasing body mass. The lower liquid pressure found with increasing body mass is discussed in terms of lower conductance of the mesothelia and possibly greater lymphatic action. In terms of the Starling-lymphatic interaction we suggest that lymphatics can generate a pressure only slightly lower than that reflecting the equilibrium of the Starling balance of forces.

Aging↗

PubMed1983

Reabsorption of a saline- or plasma-induced hydrothorax.

In supine rabbits injection of 2 ml of saline into the lower right diaphragmatic region increased pleural liquid pressure at the injection point and, to a minor extent, on the costal and mediastinal side, indicating a redistribution of liquid among the pleural compartments. Over a period of 120 min end-expiratory liquid pressure on the diaphragmatic and costal surfaces approached the control value as a result of local reabsorption. No difference in the time course of liquid pressure was found on injection of either saline or homologous plasma. This was confirmed by measuring the volume of saline or plasma remaining in the cavity 90 min after injection; the net absorption flow amounted to 0.22 ml . kg-1 . h-1. These results suggest that local absorption mechanisms are relatively independent of the Starling pressure gradients acting across the pulmonary-perfused (-10.2 and 6.6 cmH2O with saline and plasma, respectively, the negative sign indicating a reabsorption gradient) and systemically perfused mesothelium (3.3 and 20.1 cmH2O with saline and plasma, respectively).

Absorption↗

PubMed1982

Role of the diaphragm in setting liquid pressure in serous cavities.

Supraphrenic and subphrenic liquid pressures in supine dogs and rabbits were found to be about 2 cm H2O more negative than costal and mediastinal liquid pressures at the same lung height. Peritoneal liquid pressure was negative at all lung heights in dogs and slightly positive below 25% of lung height in rabbits. The vertical gradients of liquid pressure did not differ significantly in either species between the pleural and peritoneal cavities and were lower than 1 cm H2O/cm. From the peritoneal protein concentration (2.3 and 3.5 g/100 ml in dogs and rabbits, respectively) we calculated a filtration pressure for the peritoneal mesothelium and a lymphatic role was hypothesized to explain negative liquid pressures in the peritoneal cavity. The greater negativity of the subphrenic as compared with the peritoneal data could be related to a strong respiratory-dependent lymphatic action. A similar mechanism and/or a low filtration conductance of the diaphragmatic pleura may explain the costo-supraphrenic liquid pressure difference. The present results, extending previously published data on the mediastinal side of the lung, further support the existence of local differences in fluid dynamics in the pleural cavity.

Animals↗

PubMed1981

Pleural liquid pressure over the interlobar mediastinal and diaphragmatic surfaces of the lung.

Pleural liquid pressure (Pliq) was measured in the interlobar fissures and over the mediastinal apical, cardiac and diaphragmatic surface. When compared to costal values, Pliq was more subatmospheric over the cardiac region at all lung heights by about 5 cm H2O so that a costo-hilar gradient down the interlobar fissures of about 0.7 cm H2O/cm was found. No differences were found for other surfaces. Cardiac values, unlike costal ones, became more subatmospheric on increasing ventilation and heart-rate. On the basis of a Starling equilibrium a costo-hilar gradient of Pliq as well as more negative values in the cardiac surface can be explained if hydrostatic pressure in visceral pleura and/or hydraulic conductivity of parietal pleura are lower on mediastinal as compared to costal side. However the ventilation and heart-beat dependence of Pliq on cardiac region suggest a possible role of lymphatic in setting pleural liquid pressure.

Animals↗

PubMedDate not supplied

Respiratory mechanics after 180 days space mission (EUROMIR'95).

The present study reports data on respiratory function of lung and chest wall following the 180 days long European - Russian EuroMir '95 space mission. Data reported refer to two subjects studied before the mission, on day 9 and 175 in flight and on days 1, 10, 12, 27 and 120 after return. In-flight vital capacity (VC) and expiratory reserve volume (ERV) were similar to those in supine posture, namely approximately 5% and approximately 30% less than in sitting posture. On day 1 after return, VC was reduced by approximately 30% in both postures. This reflected a decrease in ERV (approximately 0.5 L) and in IC (inspiratory capacity, approximately 1.7 L) that could be attributed to a marked weakening of the respiratory muscles. Regain of normal preflight values barely occurred 120 days after return. Post-flight pressure-volume curves of the lung, chest wall and total respiratory system are equal to preflight ones. The pressure-volume curve of the lung in supine posture is displaced to the right relative to sitting posture and shows a lower compliance. As far as the lung in-flight condition resembles that occurring in supine posture, this implies a lower compliance, a greater amount of blood in the pulmonary microvascular bed, a more homogeneous lung perfusion and therefore a greater microvascular filtration rate towards lung interstitium.

Adult↗