We report the activity of recombinant human surfactant apoprotein-C (rSP-C[Cys]2) and various phospholipids in a preterm rabbit model of respiratory distress syndrome (RDS). Mixtures of rSP-C(Cys)2 and certain phospholipids had similar activity (lung compliance and lung pressure-volume behavior) to rabbit surfactant in this model. The activity of rSP-C(Cys)2 was maximal at 1 mol% protein and varied significantly with the phospholipid composition. Chemically synthesized SP-C had similar activity to rSP-C(Cys)2. Deletion of six amino-terminal residues did not affect function. Substitution of cysteines and cysteine6 with adjacent serines (rSP-C[Ser]2) by site-specific mutagenesis minimized aggregation of rSP-C but did not affect activity. Palmitoylation of cysteine5 and cysteine6 in rSP-C (rSP-C[C16]2) did not enhance the activity of rSP-C(Cys)2. We conclude that bacterial expression is a practical source of functional SP-C, and that nonacylated forms of SP-C may be useful adjuvants to phospholipids in the treatment of RDS and possibly other forms of acute lung injury.

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The elastic pressure/volume (P/V) curve obtained by the multiple linear regression (MLR) technique using a new model, was compared with the quasi-static P/V points obtained by the rapid airway occlusion technique.Seven infants were studied during mechanical ventilation using a pressure controlled mode. The resistive pressure was subtracted from airway opening pressure, thus determining the elastance related pressure, which was then plotted against the volume to make an MLR-elastance curve. Quasi-static P/V curves of the rapid occlusion technique were constructed by plotting the different inspiratory and expiratory volumes against the corresponding values of the quasi-static airway pressure.The calculated MLR-elastance curves closely fit the experimental quasi-static P/V points obtained by the occlusion technique. There were, however, some discrepancies due to the viscoelastic behaviour of the respiratory system.Although slightly altered by these discrepancies, the multiple linear regressionelastance curves did fit the observed quasi-static pressure/volume characteristics for use in clinical practice. Respiratory system elastance has been shown to exhibit a negative lung volume dependence due to the curvilinear character of static pressure/volume [1 -3] (P/V) curves. During mechanical ventilation, the lungs are frequently inflated to the nonlinear level on the P/V curve. It is generally accepted that a graphic presentation of the P/V relationship at a given respirator setting can provide great insight regarding whether or not lung overdistension occurs.The static P/V relationship, as a parameter for the elasticity of the respiratory system, can be determined by various methods. The super syringe technique is a continuous procedure of step-by-step inflation and deflation using a large syringe while the patient is disconnected from the ventilator [4]. The interrupter technique consists of rapid occlusions within a single breath cycle [5,6] or of interrupting airways at different inflation and deflation volumes [7 -9]. All occlusion data can then be plotted on a P/V diagram. The constant flow technique is performed during volume controlled mechanical ventilation using a very slow constant inflation flow of 3 L?min -1 or 9 L?min -1 , and thus pressure consumed by the flow resistance in the airway is not considered to be of any clinical relevance [10,11]. These techniques are sometimes not practical to perform or require the presence of a trained investigator and the respirator settings may need to be changed. With the increasing availability of computer-based data acquisition systems, high speed data collection and analyses are now possible using the computerized least-squares multiple regression analysis technique [12]. Using a multiple linear regression (MLR) analysis to analyse the flow and pressure changes at the airway opening during mechanical ventilation, permits dynamic mechanics to be measured noninvasively without interfering with the ventilation pattern being employed. An MLR analysis also allows...

An unusual case of biliary atresia with jejunal atresia is herein described. Only 12 cases demonstrating biliary atresia associated with a jejunal atresia have been previously reported in Japan. The pathogenesis of biliary atresia is thought to be secondary to the influence of jejunal atresia.