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D Absolom

Publications and source records attributed to D Absolom.

10 recordsLinked to original sources
PubMed1993

Pulmonary surfactant-associated protein SP-B has little effect on acyl chains in dipalmitoylphosphatidylcholine dispersions.

Synthetic human pulmonary surfactant-associated protein SP-B has been interacted with chain-perdeuterated dipalmitoylphosphatidylcholine (DPPC-d62) in aqueous dispersions, and the dispersions were investigated by magnetic resonance spectroscopy. The protein caused only small perturbations of the deuterium magnetic resonance spectra in the gel and liquid-crystal states. In an amount of 11% by weight in DPPC, it produced a small reduction in the magnitude of the first moments of the spectra in the gel and a small increase (approximately 5%) in their magnitude in the liquid crystal. In the liquid crystal the protein was observed to cause a similar effect on all portions of the acyl chain, as observed by its proportional shifting of splittings obtained from "dePaked" spectra. Using data from circular dichroism spectra, the protein was found to be about 45% alpha-helical in methanol and in DPPC dispersions. alpha-Helical content was not significantly changed by the presence of 2 mM calcium or by the packing state of the acyl chains. The presence of the protein enhanced the adsorption rate of lipid into the air-water interface when dispersions of lipids or lipid plus SP-B were injected below the interface. The results could be consistent with the protein interacting with the lipid near the head groups or arranging itself around the edges of bilayer discs, or a combination of the two orientations.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Lung function and surfactant distribution in saline-lavaged sheep given instilled vs. nebulized surfactant.

Adult sheep (35 +/- 3 kg) underwent saline lung lavage and 1.5 h of mechanical ventilation to induce acute lung injury. Animals received 100 mg lipid/kg body wt of tracheally instilled surfactant (Inst Surf) or either nebulized surfactant (Neb Surf) or nebulized saline (Neb Saline) and were killed 3 h later. Inst Surf and Neb Surf groups had significant improvements in oxygenation (P < 0.01) and peak inspiratory pressures (PIP) (P < 0.05) compared with pretreatment values. Improvements in oxygenation and PIP for Inst Surf animals were significantly greater than for Neb Surf animals (P < 0.05). Volumes of maximal pressure of quasi-static pressure-volume curves measured at the time the animals were killed were significantly greater for Inst Surf and Neb Surf animals than for animals given Neb Saline (P < 0.05). Alveolar recovery of exogenous surfactant was 100 times greater for Inst Surf animals (1,732 +/- 70 mg) than for Neb Surf animals (15.3 +/- 2.9 mg) at the time they were killed. Although there were no differences in exogenous surfactant distribution patterns at the lobar level between the two surfactant-treated groups, distribution histograms calculated for 10-g lung pieces revealed the Neb Surf animals had significantly more pieces within 25% of the mean value of 1.0 (42.7 +/- 6.9%) than did Inst Surf animals (20.8 +/- 5.5%) (P < 0.01). Exogenous surfactant therapy improved lung function with significantly different quantities of surfactant deposited in lung tissue for the two delivery methods evaluated.

Aerosols↗
PubMed1993

Treatment responses to surfactants containing natural surfactant proteins in preterm rabbits.

The in vivo function of surfactants reconstituted using natural surfactant lipid and protein constituents was evaluated in 27-day-gestation preterm rabbits. The animals were treated with protein-free surfactant lipids (LH-20), LH-20 + 5% SP-A, LH-20 + 1% SP-B, LH-20 + 1% SP-C, LH-20 + 5% SP-A + 1% SP-B + 1% SP-C (SP-ABC), natural sheep surfactant, or 4 ml/kg 0.45% NaCl (control) and then ventilated with tidal volumes of 8 ml/kg and 3 cm H2O positive end-expiratory pressure (PEEP). Ventilatory pressures (peak pressures minus PEEP) and dynamic compliances of the LH-20 + SP-C rabbits were greater (p < 0.01) than those of control, LH-20, and LH-20 + SP-A groups but lower (p < 0.05) than in the LH-20 + SP-B, LH-20 + SP-ABC, and sheep surfactant groups. Recoveries of intravascular labeled albumin in the lungs were comparable in the LH-20 + SP-B, LH-20 + SP-C, LH-20 + SP-ABC, and sheep surfactant groups and less (p < 0.01) than in LH-20 + SP-A rabbits, which had lower (p < 0.05) recoveries than did the control and LH-20 groups. The postventilation pressure-volume curves for LH-20 + SP-B and LH-20 + SP-ABC rabbits had significantly lower opening pressures, larger maximal lung volumes, and larger retained volumes on deflation relative to the LH-20 + SP-C, LH-20, and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Physiologic responses and distribution of aerosolized surfactant (Survanta) in a nonuniform pattern of lung injury.

The underlying pattern of lung injury in patients with the adult respiratory distress syndrome (ARDS) may be nonuniform. The purpose of this study was to document whether a nonuniform pattern of lung injury influences treatment responses to aerosolized exogenous surfactant. Adult sheep underwent either total lung lavage (Tot Lav) or partial lung lavage (Par Lav) with saline, and they were subsequently mechanically ventilated for 90 min. Previous studies confirmed that this procedure induces acute lung injury. Partial lavage animals had their right upper lobe (RUL) protected from lavage by balloon obstruction of the RUL bronchus, and the occlusion was removed prior to the ventilatory period. Animals in both groups were then treated with either nebulized surfactant (Neb Surf) or nebulized saline (Neb Saline) for a further 180 min. PaO2, PaCO2, and peak inspiratory pressure significantly improved for the Tot Lav-Neb Surf animals compared with pretreatment values (p < 0.01). There were no significant changes for the other three groups (Tot Lav-Neb Saline, Par Lav-Neb Surf, Par Lav-Neb Saline). Lobar distribution of aerosolized [3H]surfactant in lung tissue revealed that Par Lav-Neb Surf animals had approximately 50% of the total surfactant recovered from the RUL compared with approximately 20% recovery from the RUL in the Tot Lav-Neb Surf group. The preferential deposition of exogenous surfactant in the RUL of the Par Lav-Neb Surf group resulted in significantly less surfactant deposited in other injured regions of the lung (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1993

Changes in exogenous surfactant in ventilated preterm lamb lungs.

Preterm lambs were treated with either a surfactant from bovine lung (Survanta) or three synthetic surfactants (Exosurf), a 69:22:9 mixture of dipalmitoylphosphatidylcholine, phosphatidylglycerol, and palmitic acid prepared by heat annealing (Lipid Mixture 1) or with glass beads (Lipid Mixture 2). After 5 h of ventilation, large and small aggregate surfactant fractions were isolated from alveolar washes by centrifugation. SP-A was used as an indicator for the association of endogenous surfactant components with the treatment surfactants. The large aggregate fraction from Survanta-treated lambs contained more SP-A than did the fractions from the lambs treated with the other surfactants (p < 0.05). The surfactants used to treat the sheep and the large aggregate surfactants from alveolar washes increased compliances when tested in surfactant-deficient, immature rabbits, relative to that in control animals. The large aggregate fractions in alveolar washes from lambs treated with Survanta, Lipid Mixture 1, and Lipid Mixture 2 improved compliances in the preterm rabbits to a greater extent than did the surfactants used to treat the lambs. The small aggregate fractions were inactive as surfactants. The function of exogenous surfactant can be improved after exposure to the preterm lung. The improvement may result from the association of exogenous surfactant with components of endogenous surfactant.

Analysis of Variance↗
PubMed1991

Nebulized vs. instilled exogenous surfactant in an adult lung injury model.

Three days after subcutaneous injection of N-nitroso-N-methylurethane (NNNMU) to induce lung injury, adult rabbits were mechanically ventilated and lung function was evaluated. Each animal then received either nebulized Survanta (Neb Surv), nebulized saline (Neb Saline), nebulized gas alone (Neb Gas), or tracheally instilled Survanta (Inst Surv). The ventilation efficiency index (VEI) value increased significantly compared with pretreatment values (P less than 0.01) over a 3-h treatment period for the Neb Surv animals, whereas VEI values for the other three groups decreased after treatment (P less than 0.05). Arterial PO2-to-fraction of inspired O2 ratios and dynamic compliance values significantly decreased after treatment for the Inst Surv group (P less than 0.05). Pressure-volume curves demonstrated a significantly greater volume at maximal pressure for the Neb Surv group compared with each of the other groups studied (P less than 0.01). The calculated quantity of surfactant recovered in lung tissue for the Neb Surv group was only 4.9 +/- 1.0 mg lipid/kg compared with 100 mg lipid/kg delivered to the Inst Surv group. Surfactant administered as an aerosol resulted in modest physiological improvements in this model of lung injury and was superior to the tracheal instillation technique.

Aerosols↗
PubMed1985

Size and surface charge properties of myelin vesicles from normal and diseased (multiple sclerosis) brain.

Differences have been observed between myelin vesicles prepared from normal human central nervous system and from white matter of patients who died with multiple sclerosis (MS). The mean cross-sectional area of the vesicles was 5.69 +/- 0.17 micron 2 from normal myelin and 3.71 +/- 0.28 micron 2 for diseased myelin. Vesicle size was reduced to 4.08 +/- 0.21 micron 2 when normal myelin vesicles were prepared in the presence of 0.1 mM EDTA. The presence of Ca2+ during the preparation of the vesicles had no effect on the mean cross-sectional area. In the case of MS myelin vesicles, 0.1 mM EDTA had no effect on vesicle size, whereas the presence of Ca2+ increased the vesicle size from 3.71 +/- 0.28 to 5.40 +/- 0.31 micron 2. Electrokinetic analysis revealed that the electrophoretic mobility of normal myelin vesicles was -5.169 +/- 0.193 X 10(-8) compared with -6.093 +/- 0.202 X 10(-8) m2 s-1 V-1 for the MS myelin vesicles. The presence of 0.1 mM EDTA increased the electrophoretic mobility of the normal vesicles to -6.483 +/- 0.151 X 10(-8) m2 s-1 V-1 but did not significantly affect that of the MS vesicles. Addition of 0.1 mM Ca2+ decreased the electrophoretic mobility of both normal and MS vesicles to similar mobilities. From these data, the surface charge densities were calculated for both normal and MS myelin vesicles and found to be -2.93 and -5.39 mV m-1, respectively. The phase transition temperature determined by wide-angle x-ray diffraction studies was 63 degrees C for normal myelin vesicles and 43 degrees C for MS myelin vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗