A Combination of Short and Simple Surfactant Protein B and C Analogues as a New Synthetic Surfactant: In Vitro and Animal Experiments

PURPOSE: Pulmonary surfactants for preterm infants contain mostly animal-derived surfactant proteins (SPs), which are essential for lowering surface tension. We prepared artificial pulmonary surfactants using synthetic human SP analogs and performed in vitro and in vivo experiments. MATERIALS AND METHODS: We synthesized peptide analogues that resemble human SP-B (RMLPQLVCRLVLRCSMD) and SP-C (CPVHLKRLLLLLLLLLLLLLLLL). Dipalmitoylphosphatidylcholine (DPPC), phosphatidylglycerol (PG), and palmitic acid (PA) were added and mixed in lyophilized to render powdered surfactant. Synsurf-1 was composed of DPPC:PG:PA:SP-B (75:25:10:3, w/w); Synsurf-2 was composed of DPPC:PG:PA:SP-C (75:25:10:3, w/w); and Synsurf-3 was composed of DPPC:PG:PA:SP-B:SP-C (75:25:10:3:3, w/w). We performed in vitro study to compare the physical characteristics using pulsating bubble surfactometer and modified Wilhelmy balance test. Surface spreading and adsorption test of the surfactant preparations were measured. In vivo test was performed using term and preterm rabbit pups. Pressure-volume curves were generated during the deflation phase. Histologic findings were examined. RESULTS: Pulsating bubble surfactometer readings revealed following minimum and maximum surface tension (mN/m) at 5 minutes: Surfacten® (5.5±0.4, 32.8±1.6), Synsurf-1 (16.7±0.6, 28.7±1.5), Synsurf-2 (7.9±1.0, 33.1±1.6), and Synsurf-3 (7.1±0.8, 34.5±1.0). Surface spreading rates were as follows: Surfacten® (27 mN/m), Synsurf-1 (43 mN/m), Synsurf-2 (27 mN/m), and Synsurf-3 (27 mN/m). Surface adsorption rate results were as follows: Surfacten® (28 mN/m), Synsurf-1 (35 mN/m), Synsurf-2 (29 mN/m), and Synsurf-3 (27 mN/m). The deflation curves were best for Synsurf-3; those for Synsurf-2 were better than those for Surfacten®. Synsurf-1 was the worst surfactant preparation. Microscopic examination showed the largest aerated area of the alveoli in the Synsurf-3 group, followed by Synsurf-1 and Surfacten®; Synsurf-2 was the smallest. CONCLUSION: Synsurf-3 containing both SP-B and SP-C synthetic analogs showed comparable and better efficacy than commercially used Surfacten® in lowering surface tension, pressure-volume curves, and tissue aerated area of the alveoli.

Development of a Synthetic Surfactant Using a Surfactant Protein-C Peptide Analog: In Vitro Studies of Surface Physical Properties

PURPOSE: Pulmonary surfactant (PS) replacement has been the gold standard therapy for neonatal respiratory distress syndrome; however, almost all commercial PSs contain animal proteins. We prepared a synthetic PS by using a human surfactant protein (SP) analog and evaluated its in vitro properties. MATERIALS AND METHODS: A peptide sequence (CPVHLKRLLLLLLLLLLLLLLLL) of human SP-C was chosen to develop the peptide analog (SPa-C). The new synthetic SP-C PS (sSP-C PS) was synthesized from SPa-C, dipalmitoyl phosphatidylcholine, phosphatidyl glycerol, and palmitic acid. Physical properties of the sSP-C PS were evaluated by measuring the maximum and minimum surface tensions (STs), surfactant spreading, and adsorption rate. In addition, we recorded an ST-area diagram. The data obtained on sSP-C PS were subsequently compared with those of purified natural bovine surfactant (PNBS), and the commercial product, Surfacten(R). RESULTS: The sSP-C PS and Surfacten(R) were found to have maximum ST values of 32-33 mN/m, whereas that of PNBS was much lower at 19 mN/m. The minimum ST values of all three products were less than 10 mN/m. The values that were measured for the equilibrium ST of rapidly spreading sSP-C PS, Surfacten(R), and PNBS were 27, 27, and 24 mN/m, respectively. The surface adsorptions were found to be the same for all three PSs (20 mN/m). ST-area diagrams of sSP-C PS and Surfacten(R) revealed similar properties. CONCLUSION: In an in vitro experiment, the physical properties exhibited by sSP-C PS were similar to those of Surfacten(R). Further study is required to evaluate the in vivo efficacy.

Preparation and evaluation of lipid vesicles of camptothecin as targeted drug delivery system

Site-specific delivery of anticancer based therapy of human cancers has led to several remarkable outcomes, particularly in the therapy of breast cancer and lymphoma. Camptothecin, a plant secondary metabolite is widely used in the treatment of metastatic breast cancer and lymphoma. However its side effect profile often results in cessation of therapy. In this study the principle of both active as well as passive targeting using camptothecin loaded stealth liposomes as per the magic gun approach was followed. Stealth liposomes of camtothecin were prepared by thin film hydration method using a PEGylated phospholipid like DSPE-MPEG 2000. Similarly conventional liposomes were prepared using phospholipids like DPPC, DSPC. Conventional liposomes were coated with a hydrophilic biocompatible polymer like chitosan. It was found that chitosan coating of the conventional liposomes increased the physical stability of the liposomal suspension. Further, chitosan coated conventional liposomes and the PEGylated liposomes released the drug for a prolonged period of time, compared to the uncoated conventional liposomes. In vivo screening of the formulations for their antitumor efficacy was carried out in rats. Breast cancer was induced in female Sprague-Dawley rats using an indirectly acting chemical carcinogen DMBA [7, 12 dimethyl benz[a]anthracene]. It was found that there was significant decrease [P<0.01] in tumor volume in the rat group treated with test 2 formulation and test 1 formulation compared to standard free CPT. However the chitosan coated liposomal formulation showed a better antitumor efficacy than that of the PEGylated liposomal formulation

Biocompatible Dispersion Methods for Carbon Black

The biological activity of particles is largely dependent on their size in biological systems. Dispersion in the aqueous phase has been both a critical impediment to and a prerequisite for particle studies. Carbon black has been used as a surrogate to investigate the biological effects of carbonaceous particles. Here, biocompatible methods were established to disperse carbon black into ultrafine and fine particles which are generally distinguished by the small size of 100 nm. Carbon black with a distinct particle size, N330 and N990 were suspended in blood plasma, cell culture media, Krebs-Ringer's solution (KR), or physiological salt solution (PSS). Large clumps were observed in all dispersion preparations; however, sonication improved dispersion - averaged particle sizes for N330 and N990 were 85.0 +/- 42.9 and 112.4 +/- 67.9 nm, respectively, in plasma; the corresponding sizes in culture media were 84.8 +/- 38.4 and 164.1 +/- 77.8 nm. However, sonication was not enough to disperse N330 less than 100 nm in either KR or PSS. Application of Tween 80 along with sonication reduced the size of N330 to less than 100 nm, and dispersed N990 larger than 100 nm (73.6 +/- 28.8 and 80.1 +/- 30.0 nm for N330 and 349.5 +/- 161.8 and 399.8 +/- 181.1 nm for N990 in KR and PSS, respectively). In contrast, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) exhibited little effect. Electron microscopy confirmed the typical aciniform structure of the carbon arrays; however, zeta potential measurement failed to explain the dispersibility of carbon black. The methods established in this study could disperse carbon black into ultrafine and fine particles, and may serve as a useful model for the study of particle toxicity, particularly size-related effects.

Effect of methylprednisolone pretreatment on pulmonary permeability and dipalmitoylphosphatidylcholine content in rabbits with reexpansion pulmonary edema / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of methylprednisolone pretreatment on pulmonary lung permeability index and the content of the pulmonary surfactant dipalmitoylphosphatidylcholine (DPPC) in a rabbit model of reexpansion pulmonary edema.</p><p><b>METHODS</b>Twenty-one male New Zealand white rabbits were randomly divided into control group, reexpansion, and reexpansion+methylprednisolone pretreatment groups. The rabbit model of reexpansion pulmonary edema was established using Sakaos method. A bolus dosage of methylprednisolone (3 mg/kg) in reexpansion+methylprednisolone group group or 2.0 ml/kg normal saline in the other two groups was administered intravenously 20 min before reexpansion pulmonary edema. Bronchoalveolar lavage fluid (BALF) and arterial blood samples were collected for measurement of the total protein (TP) and DPPC contents 4 h after reexpansion, and the pulmonary permeability index was calculated.</p><p><b>RESULTS</b>The pulmonary permeability index in methylprednisolone pretreatment group was significantly lower than that in the reexpansion group (0.007∓0.002 vs 0.177∓0.004, P<0.05). Methylprednisolone pretreatment significantly increased DPPC concentration in the BALF as compared with saline treatment in the reexpansion group (61.815∓28.307 vs 101.955∓24.544 µg/ml, P<0.05).</p><p><b>CONCLUSION</b>Methylprednisolone pretreatment can increase pulmonary surfactant content and improve pulmonary permeability in the rabbit model of reexpansion pulmonary edema.</p>

Gene transfer system mediated by PEI-cholesterol lipopolymer with lipid microbubbles / 药学学报

The properties of polyethyleneimine-cholesterol cationic lipopolymer (PEI-Chol) as gene carries and its gene transfer efficiency in vitro with lipid microbubbles were presented in this paper. PEI-Chol lipopolymer was synthesized by linking cholesterol chloroformate to the amino groups of branched poly(ethyleneimine) (PEI) of 1 800. The structure and molecular weight of PEI-Chol were confirmed by IR, 1H NMR and MADI-TOF-MS (matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry), respectively. The average molecular weight of PEI-Chol was approximately 2 000. The gene delivery system of bubble/PEI-Chol/DNA was constructed by mixed PEI-Chol/pDNA (N/P 10:1) complexes with lipid microbubbles (2-8 microm) which were prepared by DPPC, DSPE-PEG2000 and perfluoropropane with the reverse phase evaporation technique. pEGFP-Cl (enhanced green fluorescent protein) was used as report gene to investigate the DNA condensing ability of PEI-Chol lipopolymer by agarose gel electrophoresis. And their cytotoxicity and in vitro transfer efficiency of different complexes were compared with each other in A549 and MCF-7. The results indicated PEI-Chol lipopolymer can condense plasmid DNA when N/P ratio upto 4, PEI-Chol complexes and bubble/PEI-Chol/DNA complexes were nontoxic to A549 and MCF-7 when formulated at the N/P ratio of 10/1 as determined by MTT assay. This bubble/PEI-Chol/DNA delivery system provided good transfer efficiency with other desirable characteristics such as against-precipitation of plasma proteins. In conclusion, bubble/PEI-Chol/DNA complex is a novel non-viral gene delivery system.

Changes of dipalmitoyl phosphatidyl choline after mechanical ventilation in patients with acute cerebral injury / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To detect the levels of dipalmitoyl phosphatidyl choline (DPPC) in the sputum of the patients with acute cerebral injury without primary pulmonary injury after mechanical ventilation treatment.</p><p><b>METHODS</b>DPPC levels in sputum of 35 patients with acute cerebral injury but without pulmonary injury were detected with high performance liquid chromatography at the beginning of ventilation and 16-20 days, 21-40 days, and 41-60 days after ventilation, respectively.</p><p><b>RESULTS</b>There was no significant difference of the DPPC levels between 16-20 days after ventilation (3.36+/-0.49) and at the beginning of ventilation (3.37+/-0.58) (P>0.05). The mean levels of DPPC decreased significantly at 21-40 days (2.87 mg/ml+/-0.26 mg/ml, P<0.05) and 41-60 days (1.93 mg/ml+/-0.21 mg/ml, P<0.01) after ventilation compared with that at the beginning of ventilation. At the same period, the peak inspiratory pressure and the mean pressure of airway increased significantly, whereas the static compliance and the partial pressure of oxygen in artery decreased significantly. Among the 25 patients who received ventilation for more than 20 days, 8 (32%) had slightly-decreased partial pressure of oxygen in artery compared with that at the beginning of ventilation.</p><p><b>CONCLUSIONS</b>Mechanical ventilation can decrease the DPPC levels, decrease the lung compliance and increase the airway pressure, even impair the oxygenation function in patients with acute cerebral injury. Abnormal DPPC is one of the major causes of ventilator-associated lung injury.</p>

Cholesteryl hemisuccinate as liposomal membrane stabilizer and its use in the preparation of saikosaponin-D liposomes / 药学学报

<p><b>AIM</b>To study the membrane stabilization effect and mechanism of cholesteryl hemisuccinate (CHEMS) on dipalmitoylphosphatidylcholine (DPPC) liposomes; Saikosaponin-D (SSD) liposomes were prepared by using CHEMS as a membrane stabilizer and its encapsulation efficiency and hemolytic activity were evaluated.</p><p><b>METHODS</b>Differential scanning calorimetry (DSC) and calcein release were used to study membrane stabilization effect of CHEMS on DPPC membrane, Fourier transform infrared spectroscopy (FT-IR) was used to study the interacting mechanism of CHEMS with DPPC, sedimentation experiment was done to study the interaction of CHEMS with SSD and hemolytic study was used to evaluate the hemolytic activity of SSD-liposomes with CHEMS as membrane stabilizer.</p><p><b>RESULTS</b>DSC analysis showed that CHEMS and cholesterol (CHOL) could all decrease the Tm value slightly and the deltaH value markedly. CHEMS was more effective than CHOL in decreasing the deltaH value of DPPC membrane. It suggested that CHEMS was more effective in increasing DPPC membrane stability. It was also proved by calcein release study carried out both in PBS and 30% plasma. The findings by FT-IR suggested that CHEMS has both hydrogen bond and electrostatic interaction with the polar head of DPPC. CHEMS did not form insoluble complex (INCOM) with SSD by sedimentation experiment. Stable SSD-liposomes were prepared using DPPC and CHEMS and decreased effectively the hemolytic activity of SSD, SSD-liposomes may be given intravenously at a concentration of 15 microg x mL(-1), while free SSD was forbidden to be given intravenously.</p><p><b>CONCLUSION</b>CHEMS was more effective than CHOL in increasing DPPC membrane stability, and it could be of great use in the preparation of cholesterol-dependent hemolytic saponins-liposomes. The hemolytic activity of SSD-liposomes was greatly reduced, allowing a possible concentration of 15 microg x mL(-1) to be intravenously administered.</p>

Biodistribution and hepatocytes targeting of cationic liposomes surface-modified with sterylglucoside and golyethylene glycol / 药学学报

<p><b>AIM</b>To investigate the biodistribution and the hepatocytes targeting of cationic liposome containing 3beta[N-( N',N'-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) and surface-modified liposomes with sterylglucoside (SG) and polyethylene glycol-distearoylphosphatidylethanolamine (PEG-DSPE).</p><p><b>METHODS</b>Cationic liposomes (CL) composed of DC-Chol and dipalmitoylphosphatidylcholine (DPPC), SG/PEG modified cationic liposome (SG/PEG-CL), both contained trace 3H-cholesterol (3H-Chol) as radiolabel, were prepared. The liposomes encapsulating 125I-labled antisense oligodeoxynucleotide (125I-asODN) (SG/PEG-CL-asODN) were also prepared. The biodistribution of CL, SG/PEG-CL, SG/PEG-C2-asODN as well as 125I-asODN solution, were studied. The radioactivities in hepatocytes and non-hepatocytes after administration of CL and SG/PEG-CL were determined by infuseing method.</p><p><b>RESULTS</b>CL and SG/PEG CL significantly aggregated in liver. The distribution of SG/PEG CL was significantly higher in hepatocytes (P < 0.01) and lower in non-hepatocytes (P < 0.01) than that of CL. The concentrations of SG/PEG-CL-asODN in liver and spleen were significantly higher than that of asODN solution (P < 0.01).</p><p><b>CONCLUSION</b>Cationic liposome modified with SG/PEG changed the distribution of asODN. Cationic liposome can target hepatocytes more effective after being modified with SG.</p>

Ocular controlled delivery of brimonidine using liposomes as a particulate carrier

The ocular activity of a single dose of brimonidine 0.2% in solution and liposomal formulations was evaluated in 28 adult patients with recently diagnosed primary open angle glaucoma. Multilamellar liposomes were prepared from dipalmitoyl phosphatidcholine and cholesterol. Stearylamine and dicetyl phosphate were used to modify the net surface charge of liposomes. The evaluation of the performance of various formulations of the drug was assessed on the basis of the influence of the drug on the intraocular pressure. Results demonstrated that the intra-ocular activity of the drug using various liposomal formulations was greater than that of solution form. Moreover, concerning the liposomal surface charge, the drug activity was greatest for positively charged liposomes, less for neutral liposomes and least for negatively charged liposomes. This could be attributed to electrostatic attraction between the negatively charged surface of the corneal epithelial and positively charged liposomal surface. In conclusion, it was clearly observed that liposomal ophthalmic drug delivery system seems to be a promising approach for the selective targeting of the drug

Experiencia en 100 prematuros con enfermedad de membrana hialina tratados con surfactante sintético / Preterm newborns with hyaline membrane disease treated with synthetic surfactant. a 100 cases experience

Introducción. El objetivo de este estudio fue describir y analizar los resultados obtenidos en 100 prematuros con enfermedad de membrana hialina tratados con ventilación mecánica intermitente (VMI) y surfactante sintético.Material y métodos. En un período de 3 años, se estudiaron 100 prematuros menores de 37 semanas de edad gestacional, mayores de 500 g con enfermedad de membrana hialina que requirieron VMI y a los cuales se les administró surfactante sintético en la modalidad de rescate, siguiendo un protocolo establecido y con un máximo de 3 dosis. Se evaluaron a las 6 y 24 horas: presión media de la vía aérea (MAP), gradiente alvéolo-arterial de oxígeno (DA-aO2) e índice de oxigenación (IO2), además de registrar sus principales complicaciones.Resultados. La mayor parte de los prematuros fueron de sexo masculino, con peso promedio de 1 609 g (ñ764) y 86 por ciento con peso adecuado para edad gestacional y con una media de 31.1 (ñ 3.7) semanas. Presentaron asfixia perinatal 80 por ciento de los prematuros, la mayoría fueron obtenidos por cesárea, requiriendo intubación endotraqueal y VMI desde el nacimiento. Del grupo de 100 prematuros 33 por ciento recibió una dosis de surfactante, 29 por ciento 2 dosis y 38 por ciento 3 dosis, mostrando los 3 grupos mejoría en MAP, DA-aO2 e IO2, posterior a las 6 horas y siendo más evidente a las 24 horas de su administración. La persistencia de conducto arterioso y la sepsis resultaron las complicaciones predominantes. El promedio en días en VMI y los de estancia hospitalaria fueron de 13 (ñ 14) y de 42 (ñ 25) respectivamente. La mortalidad global fue de 20 por ciento y la mortalidad para los menores de 1 000 g fue de 48 por ciento. Conclusiones. Con la aplicación del surfactante sintético se encontró mejoría importante de casi todos los parámetros respiratorios estudiados. El surfactante sintético es en la actualidad un arma terapéutica útil en el recién nacido con enfermedad de membrana hialina y en VMI.

A new membrane probing steroidal spin label: synthesis and applications.

The applicability of a new steroidal spin label, 3-oxo-androstan-17 beta-yl-(2",2",6",6"-tetramethyl-N-oxyl) piperidyl butan-1',4'-dioate, in studying the phase transition properties of model membrane L-alpha-dipalmitoyl phosphatidyl choline (DPPC) in the presence and absence of drugs has been explored. Its synthesis and characterization has been described herein. Besides, the localization of this spin label in lipid liposomes has been studied using electron spin resonance (ESR), differential scanning calorimetry (DSC) and 1H and 31P NMR spectroscopic techniques. The label has also been used to study the permeability of epinephrine into membrane. The results show that the spin label has a good potential as a spin probe in the study of biomembranes.

Proteínas pulmonares asociadas a sustancias con actividad surfactante7 / Pulmonary proteins associated to substances with surfactant activity

La ausencia de surfactantes pulmonares trae como consecuencia el incremento de la tensión superficial a lo largo del epitelio alveolar, provocando un colapso alveolar y la lisis de las células epiteliales. Este proceso culmina con la aparición de un síndrome de insuficiencia respiratoria, que es la causa principal de morbimortalidad en niños prematuros. Recientemente, la aplicación de mezclas de agentes surfactantes con fines terapéuticos ha constituido un gran apoyo para la terapia respiratoria, ya que permite una evolución más rápida de los niños que padecen este síndrome. Por todo esto, resulta de gran importancia el conocimiento más detallado de la función, el metabolismo y la regulación de la expresión genética de las proteíinas surfactantes, para el diseño de nuevas y mejores estrategias terapéuticas para combatir este síndrome

Hemoperfusión en intoxicación por paraquat / Hemoperfusion in paraquat poisoning

Presentamos un paciente de 3 años de edad con intoxicación por Paraquat, a quien se le practicaron las medidas de prevención de absorción del tóxico, tres y media horas después de su ingestión accidental. A las 20 horas posteriores se consideró otra alternativa terapéutica, la hemoperfusión con carbón, debido a sus condiciones clínicas estables, sin alteraciones sistémicas aparentes, pero con persistencia de la prueba cualitativa del Paraquat en orina fuertemente positiva, lo que indicaba mal pronóstico. A las 22 horas se inicia la técnica en el Servicio de Nefrología del Hospital "J. M. de los Ríos", utilizando un Hemo-Adsorda 150 C (GAMBRO), durante un período de 3 horas. No se presentaron complicaciones de trombocitopenia, hipotensión, hipoglicemia, o trastornos electrolíticos. Al finalizar, se repitió la prueba cualitativa de orina, apreciándose disminución significativa de la reacción. La evolución fue satisfactoria, sin observarse complicaciones hepáticas, renales, ni respiratorias. Su seguimiento ambulatorio 5 meses después es adecuado. Realizamos revisión de la literatura especializada, y se recomiendan pautas del manejo