Influence of surface modification of Ti6Al7Nb alloy on adhesion of poly (lactide-co-glycolide) coating (PLGA).

The paper presents the results of studies on the influence of surface topography and wettability of a Ti6Al7Nb alloy substrate on the adhesion of a PLGA coating. The alloy surface was modified using a mechanical pre-treatment including: grinding, vibration treatment, mechanical polishing, sandblasting and anodic oxidation. The polymer coating was applied to the metal substrate by a dip-coating method. The scope of the research included microscopic observations of the substrate and polymer coating using SEM and acoustic microscopy. In addition, studies on the wettability and topography of the polymer coating and the metal substrate, the thickness of the polymer coating as well as qualitative and quantitative testing of the adhesion of the polymer coating to the substrate were carried out. Coating adhesion tests were conducted for samples in the initial state and after 6 weeks exposure to Ringer's solution. Analysis of the results indicates the influence of the method used to modify the metal substrate on its topography and wettability. These parameters affect the thickness of the obtained polymer coating. Regardless the parameters of the metal substrate, a qualitative analysis of the adhesion of the coating applied to the substrate of the Ti6Al7Nb alloy did not show any delamination for both samples exposed and non-exposed to Ringer's solution. On the other hand, quantitative scratch-test studies showed different adhesion of the polymer coating to the substrate depending on the surface topography obtained by various modification methods. The cytotoxicity test conducted by the indirect method using extracts confirmed that the surface modification does not affect cell growth. The complex methods of surface pre-treatment of the alloy together with the kind of polymer selected for the study allowed to develop well adhered PLGA layers on Ti6Al7Nb intended for short term implants. The lack of delamination of the layer during 6 weeks was proved, what allows for maintaining the protection function of the layer during this period and contribute to improving biocompatibility.

Multifunctional PLGA/Parylene C Coating for Implant Materials: An Integral Approach for Biointerface Optimization.

Functionalizing implant surfaces is critical for improving their performance. An integrated approach was employed to develop a multifunctional implant coating based on oxygen plasma-modified parylene C and drug-loaded, biodegradable poly(dl-lactide-co-glycolide) (PLGA). The key functional attributes of the coating (i.e., anti-corrosion, biocompatible, anti-infection, and therapeutic) were thoroughly characterized at each fabrication step by spectroscopic, microscopic, and biologic methods and at different scales, ranging from molecular, through the nano- and microscales to the macroscopic scale. The chemistry of each layer was demonstrated separately, and their mutual affinity was shown to be indispensable for the development of versatile coatings for implant applications.

Influence of vascular endothelial growth factor (VEGF) on gastroprotection in stress-induced gastric mucosal ulcers in rats.

In the process of evolution a number of complicated mechanisms have developed to protect the gastric mucous membrane, e.g., angiogenesis and stimulation of mucosal growth. The aim of this study was to determine the role of vascular endothelial growth factor (VEGF) administered intraperitoneally in the gastroprotective response to stress-induced acute gastric ulcers in rats. A dramatic increase in the number of blood vessels was observed when VEGF was injected 24 h before stress exposure. Gastric secretion, depth of ulceration and ulceration index decreased significantly after VEGF application. The results demonstrate the gastroprotective effect of VEGF on stress-induced ulceration.

Designing bioresorbable polyester matrices for controlled doxorubicin release in glioma therapy.

The influence of the chain microstructure on release process of doxorubicin from polymeric matrices was analyzed. Aliphatic polyester copolymers with optimal chain microstructure, i.e. poly(glycolide-co-L-lactide, 15/85) (PGLA) and poly(glycolide-co-epsilon-caprolactone, 10/90) (PGCA) were synthesized for long-term doxorubicin delivery systems. Various release profiles from PGLA and PGCA matrices were obtained. The investigations revealed the most steadily doxorubicin release from PGCA matrices with 5% (w/w) of drug content. Degradation of matrices with and without drug was monitored by means of NMR spectroscopy and confirmed stability of degradation process. From PGCA matrices the increase of released doxorubicin amount was observed during first 60 days. On the contrary in case of matrices obtained from PGLA the delay of doxorubicin release was observed during first 50 days, what was caused by interaction of drug molecules with polylactide chain of polymer matrix. The interaction between doxorubicin molecules and polylactide chains was confirmed by IR spectroscopy. This fact can be used for designing of delivery systems consisting of combination of matrices with different microstructure of copolymer chains in order to adjust concentration of released doxorubicin and stabilization of drug release process.

Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro.

We assessed the rate of release of a model nucleoside (adenosine, 5%, w/w) from nine different lactide-glycolide or lactide-caprolactone polymers. The polymer discs were eluted every second day with an artificial cerebrospinal fluid at the elution rate roughly approximating the brain extracellular fluid formation rate. Adenosine in eluate samples was assayed by HPLC. Three polymers exhibited a relatively constant release of adenosine for over four weeks, resulting in micromolar concentrations of nucleoside in the eluate. This points to the necessity of further development of polymers of this types as intracerebral nucleoside delivery systems for local treatment of brain tumors.

The application of microspheres from the copolymers of lactide and epsilon-caprolactone to the controlled release of steroids.

The microspheres made of the copolymers of lactide and epsilon-caprolactone were used for the controlled release of progesterone and beta-estradiol. The copolymers contained 83-94% of l or d,l-lactide. The influence of the microstructure of lactidyl blocks in the copolymer chains on the drug release rate was studied. More uniform release rate was observed in the case of the copolymer derived from d,l-lactide as composed to l-lactide. For the copolymer containing 83-94% of d,l-lactide units the progesterone and beta-estradiol release rate in vitro was found to be practically constant within over 40 days. The in vivo studies performed on rats revealed that the period of constant release rate of beta-estradiol can be prolonged to about 70 days. The microspheres made of the applied poly-(d,l-lactide-co-epsilon-caprolactone) are the convenient system for long time release of steroids.

[Level of stress during pregnancy estimated by mothers and average weight of newborns and frequency of low birth weight]. / Poziom stresu w czasie ciazy w ocenie matek a sredni ciezar ciala noworodków i czestosc wystepowania malej urodzeniowej masy ciala.

Low birth weight is still important health problem in many countries. Children's low birth weight increases mortality, injures central nervous system, somatic, interferes with intellectual and emotional development. Low birth weight is frequently occurring in Poland--between 7-9% of live births. There are many risk factors, among them behavioural and environmental. In Poland an attention was put on chemical and physical environmental factors. Behavioural factors (stress) are disregarded. In the present paper it was decided to check the relationship between stress during pregnancy (estimated by pregnant), child birth weight and frequency of low birth weight. The research was carried out by use of a questionnaire using the "case-control study". In the research were involved 450 mothers of new-born children (the group of cases: untimely, premature delivery or child birth weight below 2500 g) and 450 mothers of new-born children (control group-physiologically delivered). Mothers were asked about their relations to the pregnancy; professional and personal stress during pregnancy was estimated. The results were analysed by counting risk ratio coefficient (RR) and correlation coefficient. The research showed, that there is no relation between acceptation of pregnancy, stress and frequency of low birth weight or the average child birth weight. The researches didn't prove unfavourable influence of stress reaction caused by professional and personal stressors on intrauterine foetus development.

Carbon-13 NMR studies of alpha-elastin.

NMR investigations of model protein of elastic fibre is presented. Detailed conformation of alpha-elastin polypeptide chain is discussed by comparison with the conformation of synthetic repeat peptides of elastin. Amino acid composition of alpha-elastin obtained from C-13 NMR spectra correlates with the results of sequencing of tropoelastin.