Evaluation of Fortetropin in geriatric and senior dogs with reduced mobility

As pets age, quality of life and mobility can be affected by pain of osteoarthritis and age-related muscle atrophy (sarcopenia). The purpose of this randomized, double-blinded, placebo-controlled study was to evaluate the effects of Fortetropin, a nonthermal-pasteurized, freeze-dried, fertilized egg yolk product, on mobility in senior dogs. Mobility scores were calculated using a standardized and validated client-based survey: the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire. Results showed mild, but statistically significant, improvement of the mobility scores for the treatment group at both week 6 (P = 0.03) and week 12 (P = 0.006) compared to the baseline score. No statistical improvement was noted at any time in the placebo group or between the treatment and placebo group.

Protein-containing synthetic surfactant versus protein-free synthetic surfactant for the prevention and treatment of respiratory distress syndrome

BACKGROUND

Respiratory distress syndrome (RDS) is a significant cause of morbidity and mortality in preterm infants. RDS is caused by a deficiency, dysfunction, or inactivation of pulmonary surfactant. Numerous surfactants of either animal extract or synthetic design have been shown to improve outcomes. New surfactant preparations that include peptides or whole proteins that mimic endogenous surfactant protein have recently been developed and tested.

OBJECTIVES

To assess the effect of administration of synthetic surfactant containing surfactant protein mimics compared to protein free synthetic surfactant on the risk of mortality, chronic lung disease, and other morbidities associated with prematurity in preterm infants at risk for or having RDS.

SEARCH STRATEGY

Standard search methods of the Cochrane Neonatal Review Group were used. The search included MEDLINE (1966 - March 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) in all languages.

SELECTION CRITERIA

Randomized and quasi-randomized controlled clinical trials were considered for this review. Studies that enrolled preterm infants or low birth weight infants at risk for or having RDS who were treated with either a synthetic surfactant containing surfactant protein mimics or a protein free synthetic surfactant were included for this review. Studies of treatment or prevention of respiratory distress syndrome were included.

DATA COLLECTION AND ANALYSIS

Data regarding mortality, chronic lung disease and multiple secondary outcome measures were abstracted by the review authors. Statistical analysis was performed using Review Manager software. Categorical data were analyzed using relative risk, risk difference, and number needed to treat. 95% confidence intervals reported. A fixed effects model was used for the meta-analysis. Heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

One study was identified that compared protein containing synthetic surfactants (PCSS) to protein free synthetic surfactants. Infants who received protein containing synthetic surfactant compared to protein free synthetic surfactant did not demonstrate significantly different risks of prespecified primary outcomes: mortality at 36 weeks postmenstrual age (PMA) [RR 0.89 (95% CI 0.71, 1.11)], chronic lung disease at 36 weeks PMA [RR 0.89 (95% CI 0.78, 1.03)], or the combined outcome of mortality or chronic lung disease at 36 weeks PMA [RR 0.88 (95% CI 0.77, 1.01)]. Among the secondary outcomes, a decrease in the incidence of respiratory distress syndrome at 24 hours of age was demonstrated in the group that received PCSS [RR 0.83 (95% CI 0.72, 0.95).

AUTHORS' CONCLUSIONS

In the one trial comparing protein containing synthetic surfactants compared to protein free synthetic surfactant for the prevention of RDS, no statistically different clinical differences in death and chronic lung disease were noted. Clinical outcomes between the two groups were generally similar although the group receiving protein containing synthetic surfactants did have decreased incidence of respiratory distress syndrome. Further well designed studies comparing protein containing synthetic surfactant to the more widely used animal derived surfactant extracts are indicated.

A novel proteoliposomal vaccine elicits potent antitumor immunity in mice

Therapeutic vaccination against idiotype is a promising strategy for immunotherapy of B-cell malignancies. Its feasibility, however, is limited by the requirement for a patient-specific product. Here we describe a novel vaccine formulation prepared by simply extracting cell-membrane proteins from lymphoma cells and incorporating them together with IL-2 into proteoliposomes. The vaccine was produced in 24 hours, compared with more labor-intensive and time-consuming hybridoma or recombinant DNA methods. The vaccine elicited T-cell immunity in vivo, as demonstrated by secretion of type 1 cytokines. It protected against tumor challenge at doses of tumor antigen 50 to 100 times lower than that previously observed using either liposomes formulated with IL-2 and secreted lymphoma immunoglobulin or a prototype vaccine consisting of lymphoma immunoglobulin conjugated to keyhole limpet hemocyanin. The increased potency justifies testing similar patient-specific human vaccines prepared using extracts from primary tumor samples.

A novel proteoliposomal vaccine induces antitumor immunity against follicular lymphoma

Clinical studies suggest that treatment with vaccines comprised of idiotype protein may be associated with improved clinical outcome in follicular lymphoma patients. The time-consuming process required to generate patient-specific vaccines is a major limitation, however. Here we report results of a pilot clinical trial with a novel autologous, tumor-derived proteoliposome vaccine formulation that could be rapidly produced within a single day. Vaccination was safe, induced autologous tumor-specific type 1 cytokine responses in 5 out of 10 follicular lymphoma patients, and was associated with induction of a sustained complete response in one patient. Other patients had large tumor burdens and progressed after a median duration of 8 months. These results suggest that further testing of this vaccine formulation, particularly in the setting of minimal disease, is warranted. Furthermore, the proteoliposome formulation may provide a model for vaccine development for other human cancers, for which tumor-associated antigens need not be defined.

Treatment of passive experimental autoimmune encephalomyelitis in SJL mice with a recombinant TCR ligand induces IL-13 and prevents axonal injury

The major goal of this study was to evaluate the efficacy and mechanism of a rTCR ligand (RTL) construct (I-A(s)/proteolipid protein (PLP)-139-151 peptide = RTL401) for treatment of SJL/J mice developing passive experimental autoimmune encephalomyelitis (EAE) that did not involve coimmunization with the highly inflammatory CFA. Our results demonstrated clearly that RTL401 was highly effective in treating passive EAE, with kinetics of recovery from disease very similar to treatment of actively induced EAE. The potent RTL401 treatment effect was reflected by a partial reduction of infiltrating mononuclear cells into CNS, minimal inflammatory lesions in spinal cord, and preservation of axons injured in vehicle-treated mice during the progression of EAE. Interestingly, in the absence of CFA, RTL401 treatment strongly enhanced production of the Th2 cytokine, IL-13, in spleen, blood, and spinal cord tissue, with variable effects on other Th1 and Th2 cytokines, and no significant effect on the Th3 cytokine, TGF-beta1, or on FoxP3 that is expressed by regulatory T cells. Moreover, pretreatment of PLP-139-151-specific T cells with RTL401 in vitro induced high levels of secreted IL-13, with lesser induction of other pro- and anti-inflammatory cytokines. Given the importance of IL-13 for protection against EAE, these data strongly implicate IL-13 as a dominant regulatory cytokine induced by RTL therapy. Pronounced IL-13 levels coupled with marked reduction in IL-6 levels secreted by PLP-specific T cells from blood after treatment of mice with RTL401 indicate that IL-13 and IL-6 may be useful markers for following effects of RTL therapy in future clinical trials in multiple sclerosis.

SP-A-enriched surfactant for treatment of rat lung transplants with SP-A deficiency after storage and reperfusion

BACKGROUND

The function of pulmonary surfactant is affected by lung transplantation, contributing to impaired lung transplant function. A decreased amount of surfactant protein-A (SP-A) after reperfusion is believed to contribute to the impaired surfactant function. Surfactant treatment has been shown to improve lung transplant function, but the effect is variable. We investigated whether SP-A enrichment of surfactant improved the efficacy of surfactant treatment in lung transplantation.

METHODS

Left and right lungs of Lewis rats, inflated with 50% O2, were stored for 20 hr at 8 degrees C. Surfactant in bronchoalveolar lavage fluid from right lungs was investigated after storage (n=6). Left lungs were transplanted into syngeneic recipients and treated with SP-A-deficient surfactant (n=6) or SP-A-enriched surfactant (n=6) just before reperfusion. Air was instilled into untreated lung transplants (n=6). Sham operated (n=4) and normal (n=8) animals served as controls. Lung function was measured during 1 hr of reperfusion; surfactant components in bronchoalveolar lavage fluid were measured after reperfusion.

RESULTS

After storage the amount of SP-A decreased by 27%, whereas surfactant phospholipids changed minimally. After reperfusion a further decrease of SP-A was paralleled by profound changes in surfactant phospholipids. Lung transplant function, however, remained relatively good. After instillation of SP-A-enriched surfactant, PO2 values were reached that approximated sham control PO2 values, whereas after SP-A-deficient surfactant treatment, the PO2 values did not improve.

CONCLUSION

Enrichment of surfactant with SP-A for treatment of lung transplants improves the efficacy of surfactant treatment.

Effects of C1 inhibitor and r-SP-C surfactant on oxygenation and histology in rats with lavage-induced acute lung injury

OBJECTIVE

To assess the effects of C1 inhibitor (INH) administration and r-SP-C surfactant application on oxygenation and lung histology in an acute respiratory distress syndrome model.

DESIGN AND SETTING

Randomized, controlled experimental study in an animal research laboratory.

MATERIAL

36 adult male Sprague-Dawley rats.

INTERVENTIONS

Animals were subjected to repetitive lung lavage. Four experimental groups and two control groups were studied: groups 1 and 2 served as controls. Animals of groups 3-6 received 200 U/kg body weight C1-INH (group 3), 25 mg/kg r-SP-C surfactant (group 4) or both (group 5) at 60 min postlavage (pl). Animals of group 6 were treated with 200 U/kg C1-INH1 at 10 min pl. Animals of group 1 were killed 60 min (min) pl, animals of groups 2-6 were killed at 210 min pl. Thereafter the lungs were excised for histological examination.

MEASUREMENTS AND RESULTS

Hyaline membrane formation, intra-alveolar neutrophil (PMN) accumulation and intra-alveolar/perivascular haemorrhage were graded semiquantitatively (0-4). Blood gases were determined 120, 150, 180 and 210 min pl. At 210 min pl pO(2) in group 4 (456+/-74 mmHg) and group 5 (387+/-155 mmHg) was significantly higher than in controls (72+/-29 mmHg) or after C1-INH monotherapy (group 3: 120+/-103, group 6: 63+/-12 mmHg). PMN infiltration after C1-INH monotherapy was significantly less severe than in controls. The combination of r-SP-C surfactant and C1-INH led to significantly lower PMN infiltration than surfactant monotherapy.

CONCLUSION

In this lavage-induced acute respiratory distress syndrome model the administration of C1-INH might be followed by a higher clinical efficacy of exogenously supplied recombinant SP-C surfactant.

Evaluation of exogenous surfactant in HCL-induced lung injury

The efficacy of exogenous surfactant administration is influenced by numerous factors, which has resulted in variable outcomes of clinical trials evaluating this treatment for the acute respiratory distress syndrome (ARDS). We investigated several of these factors in an animal model of acid aspiration including different surfactant preparations, and different delivery methods. In addition, high-frequency oscillation (HFO), a mode of mechanical ventilation known to recruit severely damaged lungs, was utilized. Lung injury was induced in adult rabbits via intratracheal instillation of 0.2 N HCl followed by conventional mechanical ventilation (CMV) until Pa(O2)/FI(O2) values ranged from 220 to 270 mm Hg. Subsequently, animals were given one of three surfactants administered via three different methods and physiological responses were assessed over a 1-h period. Regardless of the surfactant treatment strategy utilized, oxygenation responses were not sustained. In contrast, HFO resulted in a superior response compared with all surfactant treatment strategies involving CMV. The deterioration in physiological parameters after surfactant treatment was likely due to overwhelming protein inhibition of the surfactant. In conclusion, various surfactant treatment strategies were not effective in this model of lung injury, although the lungs of these animals were recruitable with HFO, as reflected by the acute and sustained oxygenation improvements.

Protective role of lung surfactant protein D in a murine model of invasive pulmonary aspergillosis

The protective effects of intranasal administration of amphotericin B (AmB), human SP-A, SP-D and a 60-kDa fragment of SP-D (rSP-D) were examined in a murine model of invasive pulmonary aspergillosis (IPA). The untreated group of IPA mice showed no survival at 7 days postinfection. Treatment with AmB, SP-D, and rSP-D increased the survival rate to 80, 60, and 80%, respectively, suggesting that SP-D (and rSP-D) can protect immunosuppressed mice from an otherwise fatal challenge with Aspergillus fumigatus conidia.

Enzyme plus light therapy to repair DNA damage in ultraviolet-B-irradiated human skin

Ultraviolet-B (UVB) (290-320 nm) radiation-induced cyclobutane pyrimidine dimers within the DNA of epidermal cells are detrimental to human health by causing mutations and immunosuppressive effects that presumably contribute to photocarcinogenesis. Conventional photoprotection by sunscreens is exclusively prophylactic in nature and of no value once DNA damage has occurred. In this paper, we have therefore assessed whether it is possible to repair UVB radiation-induced DNA damage through topical application of the DNA-repair enzyme photolyase, derived from Anacystis nidulans, that specifically converts cyclobutane dimers into their original DNA structure after exposure to photoreactivating light. When a dose of UVB radiation sufficient to induce erythema was administered to the skin of healthy subjects, significant numbers of dimers were formed within epidermal cells. Topical application of photolyase-containing liposomes to UVB-irradiated skin and subsequent exposure to photoreactivating light decreased the number of UVB radiation-induced dimers by 40-45%. No reduction was observed if the liposomes were not filled with photolyase or if photoreactivating exposure preceded the application of filled liposomes. The UVB dose administered resulted in suppression of intercellular adhesion molecule-1 (ICAM-1), a molecule required for immunity and inflammatory events in the epidermis. In addition, in subjects hypersensitive to nickel sulfate, elicitation of the hypersensitivity reaction in irradiated skin areas was prevented. Photolyase-induced dimer repair completely prevented these UVB radiation-induced immunosuppressive effects as well as erythema and sunburn-cell formation. These studies demonstrate that topical application of photolyase is effective in dimer reversal and thereby leads to immunoprotection.

Dexamethasone enhances the activity of rSP-C surfactant but not of exosurf in a rat model of the acute lung injury

The possible enhancement of surfactant activity by pretreatment with a glucocorticosteroid (dexamethasone) was investigated in a rat lung lavage model of acute lung injury. Animals received a dose of dexamethasone (10 mg/kg i.p.) prior to the protein-free surfactant preparation Exosurf (pure phospholipids containing surfactant, Wellcome GmbH, Burgwedel, Germany) and a rSP-C based surfactant, respectively. Both surfactants were intratracheally instilled at doses of 25 and 100 mg phospholipids per kg body weight and were compared with pretreatment with dexamethasone at each dose level. These groups were also compared with untreated controls and to pretreatment with dexamethasone alone with respect to improvements in oxygenation, to inhibition of infiltration of polymorphonuclear neutrophil leukocytes (PMNL) and to influence formation of hyaline membranes. Dexamethasone alone had no influence on the reduced PaO(2) but reduced the infiltration of PMNL and the formation of hyaline membranes. Dexamethasone improved the oxygenation at both doses of rSP-C surfactant. At the low dose of rSP-C surfactant there were additional effects detectable with regard to histopathologic improvements. In contrast, dexamethasone had no additional effect on oxygenation and formation of hyaline membranes when combined with Exosurf. Only the infiltration of PMNL was decreased by combined treatment with dexamethasone and Exosurf. The effect was comparable to that of pretreatment with dexamethasone alone. In this animal model, pretreatment with dexamethasone showed additional effects on rSP-C surfactant that were superior to each treatment alone. From the comparison of rSP-C surfactant with the synthetic surfactant preparation Exosurf, we conclude that the activity of Exosurf cannot be improved substantially by additional pretreatment with drugs like glucocorticosteroids.

Modified natural and synthetically reconstituted surfactant therapies for acute lung injury caused by endotoxin in rats

BACKGROUND

Impairment of surfactant is involved in development of acute respiratory distress syndrome. To develop artificial surfactant substitute for clinical use, we prepared synthetically reconstituted surfactant (SRS) by adding porcine surfactant-associated protein B and C (SP-B and SP-C) to synthetic phospholipids, and compared its effect with that of modified natural surfactant (MNS) in rats with acute lung injury caused by endotoxin.

METHODS

Escherichia coli endotoxin (71+18 mg x kg(-1), mean+/-SD) was injected into the tracheas of 27 anesthetized and mechanically ventilated rats (FI(O2) of 1.0). When the PaO2 had decreased to below 26.7 kPa, the rats were randomly assigned to three groups. The MNS and SRS groups (n=9, each) were given 100 mg x kg(-1) of MNS and SRS through the airway, respectively. The control group (n=9) was given air in the same volume.

RESULTS

The PaO2 of the control group remained below 13.3 kPa until the end of the experiment (6 h after the assignment). The PaO2 of the MNS group increased to 45.3+/-9.5 kPa and that of the SRS group to 45.5+/-3.7 kPa 0.5 h after the assignment (P<0.05 vs. control group). The PaO2 of both groups remained above 40 kPa throughout the experiment.

CONCLUSION

In this acute lung injury model, the effects of replacement therapy with surfactant consisting of synthetic phospholipids, SP-B and SP-C, were the same as those observed with MNS. These results warrant development of surfactant substitutes based on natural SP-B and SP-C, and synthetic phospholipids.

A rat model of acute respiratory distress syndrome (ARDS) Part 2, influence of lavage volume, lavage repetition, and therapeutic treatment with rSP-C surfactant

The influence of lavage volume, and lavage repetition with physiological saline solution (groups 1-3: 3x4, 4x4, 5x4, groups 7-9: 3x8, 5x8, 7x8, mL per animal) was studied in a rat lung lavage model of the acute respiratory distress syndrome (ARDS). Anesthetized and tracheotomized rats (12 rats/group) were pressure-controlled ventilated with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration: expiration ratio of 1:2, peak inspiratory pressure of 28 cm H2O at positive end-expiratory pressure of 8 cm H2O during the whole experimental period. To investigate the influence of therapeutic treatment, a recombinant surfactant protein C (rSP-C) containing surfactant was used. Therefore, rats which received a lavage of 4x4 mL per animal (groups 4 to 6) or 7x8 mL per animal (groups 10-12) were treated intratracheally with surfactant doses of 12.5, 25, or 100 mg phospholipids (PL) per kg body weight (bw). In all groups, partial arterial oxygen pressures (PaO2, mm Hg) and partial arterial carbon dioxide pressures (PaCO2, mm Hg) were determined 30 min before, directly after, and 5, 30, 60, 90, 120, 150, 180, and 210 min after the last lavage. Additionally, animals were euthanized 210 min after the last lavage for semiquantitative histopathological grading of coded lung slides. Grading was performed with respect to the severity of hyaline membrane formation (HM), margination and infiltration of polymorphonuclear neutrophil leukocytes (PMNL) into the lung alveoli and interstitial and intraalveolar edema (E). The intrapulmonary distribution of intratracheally applied rSP-C was estimated in selected lung slides stained with polyclonal anti-rSP-C antibody and was compared to unlavaged control rats and unlavaged rats which received 100 mg/kg bw rSP-C. The repetitive lavage depleted the lung from its natural surfactant resources leading to a pathophysiological cascade similar to that of the acute respiratory distress syndrome. PaO2 levels and HM formation showed a lavage-induced decrease. Both changes were significantly dependent on the repetition and volume of the lavage; however, the parameters PMNL and E did not show such a dependence. Treatment with rSP-C surfactant significantly improved oxygenation and reduced HM-formation in a dose-dependent manner independent from the lavage volume. All doses of rSP-C surfactant showed no clear influence on the parameters PMNL and E independently from the lavage volume. In lavaged rat lungs (ARDS-model), the exogenously applied rSP-C was distributed homogeneously along the alveolar lining. Unlavaged rats that received a similar dose of rSP-C showed a marked inhomogeneous extracellular distribution, mainly associated with larger bronchi, while the type II pneumocytes were stained positively in unlavaged control and unlavaged rSP-C treated rats.

CONCLUSION

This model mimics very closely the wide spectrum of the clinical situation of human acute lung injury (ALI) because the variation of lavage volume and repetition lead to reproducible different severity grades and states of ALI. The significant reduction of pathognomic changes due to treatment with rSP-C surfactant showed that this is a useful model to estimate the influence of therapeutic concepts in ALI and ARDS.

Principles of surfactant replacement

Surfactant therapy is an established part of routine clinical management of babies with respiratory distress syndrome. An initial dose of about 100 mg/kg is usually needed to compensate for the well documented deficiency of alveolar surfactant in these babies, and repeated treatment is required in many cases. Recent experimental and clinical data indicate that large doses of exogenous surfactant may be beneficial also in conditions characterized by inactivation of surfactant, caused by, for example, aspiration of meconium, infection, or disturbed alveolar permeability with leakage of plasma proteins into the airspaces. The acute response to surfactant therapy depends on the quality of the exogenous material (modified natural surfactants are generally more effective than protein-free synthetic surfactants), timing of treatment in relation to the clinical course (treatment at an early stage of the disease is better than late treatment, and may reduce the subsequent need for mechanical ventilation), and mode of delivery (rapid instillation via a tracheal tube leads to more uniform distribution and is more effective than slow airway infusion). Treatment with aerosolized surfactant improves lung function in animal models of surfactant deficiency or depletion, but is usually associated with large losses of the nebulized material in the delivery system. Furthermore, data from experiments on immature newborn lambs indicate that treatment response may depend on the mode of resuscitation at birth, and that manual ventilation with just a few large breaths may compromise the effect of subsequent surfactant therapy. The widespread clinical use of surfactant has reduced neonatal mortality and lowered costs for intensive care in developed countries. The hydrophobic surfactant proteins SP-B and SP-C are probably essential for optimal biophysical and physiological activity of exogenous surfactants isolated from mammalian lungs, and the dose-effectiveness (in part reflecting resistance to inactivation) can be further improved by enrichment with SP-A. The development of new artificial surfactant substitutes, based on synthetic analogues of the native surfactant proteins, is an important challenge for future research.

Synthetic surfactant protein analogues

Surfactant preparations for the treatment of respiratory distress syndrome (RDS) that contain phospholipids and small amounts of the two hydrophobic proteins, SP-B and SP-C, are presently obtained from animal lungs. Since structural information about SP-B and SP-C is available, it appears possible to design analogues that can replace the native proteins in synthetic surfactants. SP-C contains a single helix, but analogues with the poly-Val sequence of the native molecule do not fold into a native-like alpha-helical conformation. However, replacement of all Val with Leu yields efficient folding into a helical structure and Leu-based SP-C analogues effectively accelerate spreading of surfactant lipids and exhibit some physiological activity in animal models of RDS. The inferior in vivo activity of synthetic surfactants containing SP-C only compared to that of surfactant preparations derived from natural sources may be caused by a lack of covalently linked palmitoyl groups in the analogues and/or absence of SP-B. SP-B is significantly larger than SP-C and has a tertiary fold of several amphipathic helices in a dimeric structure. A single simplified amphipathic helical peptide containing only Leu and Lys does not mimic the surface properties of SP-B in vitro. These circumstances make the design of SP-B analogues from solely structural considerations less likely to be successful than in the case of SP-C.

Comparison of rSP-C surfactant with natural and synthetic surfactants after late treatment in a rat model of the acute respiratory distress syndrome

1. In a previous paper we showed that an SP-C containing surfactant preparation has similar activity as bovine-derived surfactants in a rat lung lavage model of the adult respiratory distress syndrome. In this study surfactant was given ten minutes after the last lavage (early treatment). In the present investigation we were interested how different surfactant preparations behave when they are administered 1 h after the last lavage (late treatment). 2. Four protein containing surfactants (rSP-C surfactant, bLES, Infasurf and Survanta) were compared with three protein-free surfactants (ALEC, Exosurf and the phospholipid (PL) mixture of the rSP-C surfactant termed PL surfactant) with respect to their ability to improve gas exchange in this more stringent model when surfactant is given one hour after the last lavage. For better comparison of the surfactants the doses were related to phospholipids. The surfactants were given at doses of 25, 50 and 100 mg kg(-1) body weight. The surfactants were compared to an untreated control group that was only ventilated for the whole experimental period. 3. Tracheotomized rats (8-12 per dose and surfactant) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min(-1), inspiration expiration ratio of 1:2, peak inspiratory pressure of 28 cmH2O at positive endexpiratory pressure (PEEP) of 8 cmH2O. Animals were ventilated for one hour after the last lavage and thereafter the surfactants were intratracheally instilled. During the whole experimental period the ventilation was not changed. 4. Partial arterial oxygen pressures (PaO2, mmHg) at 30 min and 120 min after treatment were used for statistical comparison. All protein containing surfactants caused a dose-dependent increase of the reduced PaO2 values at 30 min after treatment. The protein-free surfactants showed only weak dose-dependent increase in PaO2 values at this time. This difference between the protein-containing and the protein-free surfactants was even more pronounced when comparing the PaO2 values at 120 min after treatment. Only rSP-C surfactant, bLES and Infasurf showed a dose-dependent increase in PaO2 at this time. 5. With this animal model of late treatment it is possible even to differentiate between bovine derived surfactants. The differences between protein-containing and protein-free surfactants become even more pronounced. From the comparison of rSP-C surfactant with bovine-derived surfactants and the PL surfactant without rSP-C, it can be concluded that addition of rSP-C is sufficient to achieve the same activity as that of natural surfactants.

Synthetic mimics of surfactant proteins B and C: in vitro surface activity and effects on lung compliance in two animal models of surfactant deficiency

Synthetic surfactant peptides SP-B1-78 and SP-C1-31 in a standard phospholipid mixture have been employed to examine the correlation between in vitro surface activity and in vivo function of synthetic surfactant preparations in the isolated rat lung and premature rabbit models of respiratory distress syndrome. Monolayer techniques showed that SP-B peptides have a high propensity for association with a phospholipid structure. By dynamic respreading, synthetic SP-B and SP-C showed rapid spreading and attained low surface tensions. Used as replacement surfactants in two animal models, these synthetic surfactant preparations partially restored lung compliance in lavaged rats and premature rabbits better than a pure phospholipid preparation and to a degree comparable to clinical surfactant, measured by pressure/volume curves. Our data confirm that in vitro functional determinations of synthetic surfactant peptides are instrumental in the preparation of replacement surfactants, and that dispersions thus selected represent viable therapeutic alternatives to current treatments for respiratory distress syndrome.

Spiking Survanta with synthetic surfactant peptides improves oxygenation in surfactant-deficient rats

The hypothesis that the in vivo function of Survanta (Beractant) can be improved by supplementation with synthetic surfactant peptides B and C was tested in a surfactant-deficient rat model. Full length surfactant protein-B (SP-B1-78) (B) and palmitoylated surfactant protein-C (SP-C1-35) (C), and synthetic KL4 peptide were added to Survanta after extraction, creating extracted Survanta (ES) with 1% B, 2% B, and 2% B plus 1% C, or mixed with Survanta without extraction, creating modified Survanta (S) with 2% B, 2% B plus 1% C, and 2% KL4. Adult rats were ventilated with 100% oxygen, tidal volumes (VT) of 7.5 ml/kg and a rate of 60/min, and were lavaged until the PaO2 dropped below 80 mm Hg, when 100 mg/kg of surfactant was instilled. After 15 to 60 min of ventilation, pressure-volume (P-V) curves were generated in situ. Instillation of ES or S with 2% B plus 1% C led to the greatest increase in oxygenation, closely followed by ES and S with 2% B, and more distantly by S plus 2% KL4. TLC was comparable among the ES and S groups, but greater than that of air-placebo controls. These data suggest that spiking of Survanta with synthetic SP-B and SP-C increased oxygenation more effectively than B or KL4 alone in this surfactant-deficient rat model.

Lung function in premature rabbits treated with recombinant human surfactant protein-C

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.

Synthetic protein analogues in artificial surfactants

Today, airway instillation of surfactant preparations is a generally used treatment for respiratory distress syndrome in premature infants. Most commercially available surfactants are purified from animal lungs and contain lipids, mainly phospholipids, and about 2% of the hydrophobic surfactant proteins B and C (SP-B and SP-C). During the last half-decade the main structural properties of these proteins have been clarified and this knowledge now makes it possible to design synthetic analogues for future use in artificial surfactants.

Foreign body reaction to exogenous pulmonary surfactant in an infant with hydrops and cardiomyopathy

We present a hydropic infant who received exogenous surfactant and who had Noonan phenotype with hypertrophic cardiomyopathy. The infant had clinically diagnosed stridor for which bronchoscopy did not identify an origin. He died at 30 days of age. The bronchioles showed numerous eosinophilic plugs with a foreign body giant cell reaction. The plugs were positively immunostained with anti-aposurfactant protein B.

Surfactant protein-B supplementation improves in vivo function of a modified natural surfactant

The effect of the addition of surfactant protein (SP)-B or SP-B plus SP-C (SP-BC) to a surfactant made from bovine lung (Survanta) was evaluated in 27-d-gestation preterm rabbits. The animals were treated with Survanta, Survanta + 2% SP-B, Survanta + 3% SP-BC, or sheep surfactant. They were then ventilated with 3 cm H2O positive end-expiratory pressure and tidal volumes of 8 mL/kg. Survanta + 2% SP-B was prepared by adding SP-B in water to Survanta or by adding SP-B in chloroform [SP-B(Chl)] to lipid-extracted Survanta. Dynamic compliances of the Survanta + 2% SP-B(Chl)- and Survanta + 3% SP-BC-treated rabbits were greater (p < 0.05) than those treated with Survanta or Survanta + 2% SP-B in water and were comparable to sheep surfactant. Postventilation pressure-volume curves for the groups treated with Survanta supplemented with SP-B had significantly larger retained volumes on deflation compared with those treated only with Survanta (p < 0.01). The effects of ventilation style on the responses were assessed by ventilating other groups of rabbits treated with Survanta, Survanta + 0.5% SP-B(Chl), Survanta + 2% SP-B(Chl), or sheep surfactant with tidal volumes of 10 mL/kg and 0 cm H2O positive end-expiratory pressure. SP-B (2%) augmented the in vivo function of Survanta without positive end-expiratory pressure, and 0.5% SP-B had no effect. Infasurf, a surfactant with more SP-B, was more effective than Survanta when tested in the preterm rabbits. SP-B is a critical factor for optimum immediate surfactant function.

Surfactant protein B deficiency: antenatal diagnosis and prospective treatment with surfactant replacement

An infant with a family history of congenital alveolar proteinosis associated with surfactant protein B (SP-B) deficiency was identified when SP-B was not detected in amniotic fluid obtained at 37, 38, and 40 weeks of gestation. Surfactant replacement with commercially available preparations that contained SP-B was begun soon after delivery. Progressive respiratory failure developed despite continued surfactant replacement, corticosteroid therapy, and extracorporeal membrane oxygenation. The infant died at 54 days of age while awaiting lung transplantation. Surfactant extracted from amniotic fluid, bronchoalveolar lavage fluid, and lung tissue had no phosphatidylglycerol; surface tension was 24 dynes/cm (normal, < 10 dynes/cm) and did not decrease with in vitro addition of exogenous SP-B. Pulmonary vascular permeability measured with positron emission tomography was twice normal. At autopsy the alveolar proteinosis pattern was less prominent than that seen in affected siblings. Immunoreactivity of SP-B was absent in type II cells, but numerous foreign body granulomas with central immunoreactivity for SP-B and surfactant protein C were present. We conclude that exogenous surfactant replacement did not normalize surfactant composition, activity, or pulmonary vascular permeability. These findings suggest that endogenous SP-B synthesis is necessary for mature surfactant metabolism and function.

Surfactant proteins and anti-surfactant antibodies in sera from infants with respiratory distress syndrome with and without surfactant treatment

The presence of surfactant protein antigenemia and of surfactant protein antibodies was determined in serum from surfactant-treated and control infants with respiratory distress syndrome who were enrolled in a prospective randomized clinical trial. The surfactant used for treatment (surfactant TA) contained surfactant proteins (SPs) B and C and no SP-A. Enzyme-linked immunosorbent assays (ELISAs) that identify surfactant-associated proteins and ELISAs that identify IgG or IgM directed against surfactant proteins were used to investigate sera from these infants obtained prior to treatment, at 1 week of age, and at 2 months of age. There were no significant differences between average values in the surfactant-treated and control groups at each time period. However, in the control group, averaged results from ELISAs that identify SP-A and that identify IgM antibodies to SP-A or to SP-B, C showed significant differences between pretreatment sera and sera obtained at 1 week of age. No significant differences were noted in averaged results for IgG. Positive ELISA values were more frequently found in the control group than in the surfactant-treated group with regard to SP-A, and IgM against SP-A and SP-B, C in sera from neonates at 1 week of age. No positive ELISA values were found in sera from infants at 2 months of age. It is concluded that some patients with severe respiratory distress syndrome presumably leak surfactant proteins into the circulation and that this induces transient low titers of IgM antibody. This occurrence is decreased with surfactant treatment. Surfactant treatment may reduce leak of surfactant proteins into the vascular space by reducing lung damage.

Failure to detect surfactant protein-specific antibodies in sera of premature infants treated with survanta, a modified bovine surfactant

Serum from premature infants enrolled in either single-dose or multidose surfactant replacement studies with bovine lung-based exogenous surfactant (Survanta) were analyzed for antibodies reactive with mixtures of bovine surfactant proteins SP-B and SP-C. Sera from 404 premature infants enrolled in single-dose studies and 1024 premature infants enrolled in multidose studies were analyzed, representing a total of 987 samples and 2743 serum samples, respectively. The sera were obtained from treated and control infants at the time of treatment and 1 week, 4 weeks, and 6 months thereafter. Polyclonal antisera generated in rabbits against the small molecular weight proteins were uniformly reactive with the bovine surfactant test antigens; however, antibodies reacting with the surfactant proteins were never detected by immunoblot analysis with the infant sera. Antibodies against common human viral antigens were readily detected in infant serum samples. The horseradish-peroxidase conjugated second antibodies (antihuman immunoglobin G or antihuman immunoglobins A, G, and M) used in the studies were highly reactive with both immunoglobin G and immunoglobin M classes of human antibodies. Therefore there was failure to detect specific immunological responses to the bovine surfactant proteins present in Survanta after single or multiple doses of exogenous surfactant administered in the perinatal period.