Preparation and characterization of a novel antimicrobial film dressing for wound healing application

Antibacterial activity and good mechanical properties are some of the characteristics required for an appropriate film dressing. A novel polymer blend was developed for wound healing application. Twenty-four formulations using the polymers chitosan, poly(vinyl alcohol) and/or ɛ-Polylysine and the plasticizer glycerol were designed using factorial design and then the films were prepared by the casting/solvent evaporation method. Seventeen films were obtained among the twenty-four proposed formulations that were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Mechanical properties, such as tensile strength (σ), elongation at break (ɛ) and Young's modulus (Y) as well as antibacterial properties were determined. The best candidate was then further analyzed with regard to porosity, Water Vapor Transmission Rate (WVTR), swelling and cytotoxicity experiments. The results showed a film with semi-occlusive characteristics, good mechanical properties and no toxic. Incorporation of ɛ-Polylysine increased antibacterial activity against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria

Bacteriostatic effect of ε-polylysine and its effect on urine lead level / 中国职业医学

OBJECTIVE: To evaluate the bacteriostatic effect of ε-polylysine( ε-PL) on four common putrefactive bacteria including Staphylococcus aureus,Enterococcus faecalis,Pseudomonas aeruginosa,and E. coli and its effect on urine lead level. METHODS: Broth dilution method was used for the determination of the minimum inhibitory concentration( MIC) ofε-PL on the four kinds of putrefactive bacteria; the inhibitory effects of ε-PL with final mass concentration of 40. 000 mg / L on the urine sample were observed; graphite furnace atomic absorption spectrometry was used for determining the lead level in the 40. 000 mg / L( mass concentration) ε-PL solution and the urine lead level in normal healthy groups; the bacteriostatic effects of ε-PL and nitric acid were compared. RESULTS: The MIC of ε-PL on Staphylococcus aureus,Enterococcus faecalis,Pseudomonas aeruginosa,and E. coli was 40. 000 mg / L. There was no bacterial growth in the urine sample with40. 000 mg / L( mass concentration) ε-PL when urine was kept at room temperature for 24 hours to 15 days. The lead level was < 2. 0 μg / L in the 40. 000 mg / L( mass concentration) ε-PL solution. When the ε-PL with final mass concentration of 40. 000 mg / L and the nitric acid with a volume fraction of 1. 0% were respectively used as the antiseptics,the descending rates of the lead levels in the urine samples were similar,and after the urine sample was preserved for 15 days,the descending rates of the urine lead were both smaller than 10. 0% after be stored for 15 days. CONCLUSION: ε-PL can substitute nitric acid as a new natural preservative for preservation of samples for urine lead determination.

The Influence of PEG Modification on EGF-PLL Binding Capacities to EGFR / 生物化学与生物物理进展

Cationic polymers are being developed quickly as gene delivery vectors. For in vivo gene delivery, the cationic polymers are usually further modified by hydrophilic polymer grafting or ligand conjugation, which have been shown to increase the vector stability, gene delivery efficiency and specificity greatly. Some previous research had shown that modified hydrophilic polymer may partly shield the targeting ligand and result in poor delivery specificity. Developing a method to evaluate the influence of PEG modification on targeting delivery is particularly critical to cationic polymer design and gene therapy development. One of most commonly used cationic polymer polylysine (PLL) was chosen as a model. Targeting ligand epidermal growth factor(EGF)was conjugated with PLL to form PLL-EGF. Then hydrophilic polymer polyethylene glycol (PEG) with molecular mass 7 000 and 20 000 were used to modify PLL-EGF respectively to generate PEG7000-g-PLL-EGF and PEG20000-g-PLL-EGF. In BIAcore experiments, epidermal growth factor receptor (EGFR) was conjugated onto BIAcore chip and various PEG modified PLL-EGF solutions were flowed over the chip. By observing the change of RU value, the specific interaction of EGF to EGFR was compared. Compared with PLL-EGF, PEG modified PLL-EGF showed lower association rate and higher disassociation rate to EGFR. Furthermore, compared to PEG7000 modified PLL-EGF, PEG20000 modified PLL-EGF got lower association rate and higher disassociation rate to EGFR. The Scatchard analysis results showed that the interactions between EGFR and PLL-EGF or PEG-PLL-EGF are non-linear. It can be concluded that PEG modification indeed reduced the association rate and enhanced the dissociation rate of EGF to EGFR. The length of PEG chain was also a key factor to influence interaction between ligand and receptor. The results showed that it was critical important to evaluate the influence of PEG modification on delivery specificities. The BIAcore method developed in this paper can successfully evaluate the influence, which would be important for cationic polymer design and its application as potential non-viral gene delivery vectors.

Function study on cryopreservation of APA microencapsulated bovine chromaffin cells / 国际生物医学工程杂志

Objective To observe the morphology, cell viability and secretion function of catecholamine of the alginate-polylysine-alginate (APA) microencapsulated bovine chromaffin cells (BCCs) before and after cryopreserving with liquid nitrogen. Methods The APA microencapsulated BCCs were cryopreserved with dimethyl sulfoxide as cryopreservative agent by slow cooling and rapid rewarming for revivification. The change of cell function was observed by detecting the cell viability and secretion of catecholamine. Results As compared with the precryopreseving cells, the morphology and cell viability of the resuscitated APA microencapsulated BCCs showed no significant change. The catecholamine secretion volume of BCCs remained 80% of that by the precryopreserving cells. Conclusion It demonstrates that the resuscitated cryopreserved APA microencapsulated BCCs still remained good morphology, cell viability and secretion function of catecholamine.

Hypothermia Methods Used in Low Temperature Preservation of Alginate-Polylysine-Alginate Microcapsules / 中国康复理论与实践

@#ObjectiveTo explore the methods of low temperature preservation for alginate-polylysine-alginate (APA) microcapsules.MethodsAPA microcapsules were prepared with static electricity, and underwent hypothermal treatment respectively through methods of program control, gradient by icebox and put in liquid nitrogen directly, finally preserved in liquid nitrogen. The form and permeability of APA microcapsules were checked after rewarming.ResultsThe rates of integrity, crenation and damage were (91.2±1.57)%, (3.1±0.81)% and (5.7± 2.62 )% in the program control group; (85.3±1.42)%, (5.2±0.74)% and (9.5± 3.81 )% in the gradient by icebox group; (14.5±1.57)%, (84.1±3.47)% and (1.4±2.62)% in the directly put in liquid nitrogen group. The membrane permeability of full APA microcapsules after frozen and reworming was not changed obviously.ConclusionThe program control method can preferably preserve APA microcapsules at low temperature and keep them having normal form and permeability.

Target delivery of lactose poly-L-lysine combined HSV-TK to human liver cancer cells / 中国医师杂志

Objective To explore a new molecular target for HSV-tk/GCV system in human liver cancer therapy.Methods The lactose and poly-L-lysine covalently linked compound(Lac-PLL) were prepared by using reductive amination methods and purified by using Sephadex G10 gel filtration.The value of n was determined by methods of phenol-vitriol colorimetry.The plasmid r-pAs16Dr was mixed with the conjugate to form a gene delivery complex named GlanPLL-r-pAs16Dr.The GlanPLL-r-pAs16Dr was transformed to different cell lines such as HepG2 and A549 to confirm the expression of RFP.The expression of HSV-tk was confirmed by RT-PCR.Cells with various concentrations of GCV were observed at different time points using MTT.Results The PLL modified by 34 Lac was obtained by using chemical synthesis.The RFP was expressed in HepG2 by 48h after transfection,and was not expressed in A549.The expression of HSV-tk was only detected in HepG2 using RT-PCR.The HepG2 transformed with GlanPLL-r-pAs16Dr was sensitive to GCV and the growth inhibiting rate was 70.5% with the treatment of low concentration of GCV(1mg/L) for 3 days.The A549 was not sensitive to GCV.Conclusion Lac-PLL,which is easy to prepare,is an efficient carrier for HSV-tk to be delivered to hepatoma cell lines by binding to ASGPR.

Effects of Polylysine Coating on GH3 Rat Pituitary Tumor Cells in Culture / 대한해부학회지

GH3 cells are derived from rat pituitary tumor cells that secrete prolactin and growth hormone, and important in studying prolactin-secreting pitutary tumors. This study was performed to examine the effects of polylysine on growth and differentiation of GH3 cells by means of (a) cell attachment assay (b) cell count and bromodeoxyuridine labeling and (c) immunohistochemistry for prolactin in the absence or presence of epidermal growth factor (EGF). Cell shape, attachment to the culture surface and growth of GH3 cells were not affected by polylysine coating. The percentages of prolactin-immunoreactive cells were higher in the cells cultured on the polylysine-coated surface compared to those on the plastic surface. Cell number and BrdU incorporation were lower in the EGF-treated cells on both culture surfaces. The results provided basic information on the effects of polylysine coating on GH3 cells in culture and suggested that polylysine coating was useful for the study on GH3 cells because it enhanced cell differentiation as well as it provided stronger attachment than plastic surfaces.

Penicilina y pruebas de sensibilidad / Penicillin and hypersensitivity test

Se hace un recuento histórico sobre la alergia penicilínica y las pruebas de sensibilidad; se presentan las bases inmunológicas, las manifestaciones clínicas y los factores de riesgo asociados a esta hipersensibilidad. Se explica detalladamente la metodología necesaria para llevar a cabo pruebas cutáneas que sean de valor clínico.

Information is summarized in this review on the history, immunological bases, clinical manifestations and risk factors associated with penicillin allergy. A detailed methodology is explained to perform clinically significant skin tests

Screening of Poly-?-lysine-producing Strain and its Fermentation Technology / 微生物学通报

A strain with 2 g/L yield of poly-?-lysine was firstly screened from soil on an agar plate containing methylene blue and then further selected by a flask experiment. The strain was preliminarily identified as Streptomyces albulus. The experiment about medium optimization showed that glucose was the best carbon sources and yeast extract and (NH_4)_2SO_4 were the best compound nitrogen sources. The yield of ?-PL reached 3.9 g/L with optimal medium.

Screening and Identification of ?-PL Producing Strain / 微生物学通报

A simple and sensitive method was developed to screen ?-PL p ro duced strains from soils. 150mg/L K_2Cr_2O_7 was added to th e solid medium for actinomycetes enriching. A basic dye, methylene blue, incorp orated in the agar plate to detect alkali producers, because dye reacted with th e secreted basic polymers by electrostatic interaction with the secreted basic p dymers and formed special zoon. And then dragendorff regent was used to detect alkaloid producers. Four ?-PL producers were obtained by TLC analysis. Meanw hile, phylogenetic analysis of PL6-3 strain, including morphology, physiologica l and biochemical characters and chemotaxomy were performed and phylogenetic tre e was constructed based on the 16S rDNA sequences. And the results indicated th at PL6-3 strain is a member of Kitasatospora.

Model flavoproteins : Interaction of ribofIavin-5'-monophosphate with poly-( α –L-lysine) and poly-( α -L-histidine).

The interactions of flavin mononucleotide (riboflavin-5'-monophosphate) with two polypeptides, poly-(α-L-lysine) and poly-(α-L-histidine) in water and 0.05 Μ phosphate buffer were studied by measuring circular dichroism in the pH range 3 to 11. The interation of flavin mononucleotide with the two polypeptides was due to hydrophobic as well as ionic associations and was further influenced by the involvement of the ribityl side chain. The results of the present study have shown that small changes in the environmental conditions of the interacting molecules could modify their mode of interaction considerably.