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.

Repeatability of knee impulsive loading measurements with skin-mounted accelerometers and lower limb surface electromyographic recordings during gait in knee osteoarthritic and asymptomatic individuals.

OBJECTIVES: To determine the repeatability of knee joint impulsive loading measurements with skin-mounted accelerometers (SMAs) and lower limb surface electromyography (EMG) recordings during gait. METHODS: Triaxial SMA and EMG from 4 muscles during level and stair walking in nine healthy and nine knee osteoarthritis (OA) subjects were used. The initial peak acceleration (IPA), root mean square (RMS), maximal acceleration transient rate (ATRmax) and mean EMG activity (EMGact) were calculated. The coefficient of variation (CV) and the intraclass correlation coefficient (ICC) were calculated to measure repeatability. RESULTS: The CV and ICC of RMS accelerations ranged from 4.9% to 10.9% and from 0.69 to 0.96 in both study groups during level walking. The CV and ICC of IPA and ATRmax varied from 7.7% to 14.2% and from 0.85 to 0.99 during level and stairs up walking in healthy subjects. The CV and ICC of EMGact ranged from 8.3% to 31.7% and from 0.16 to 0.97 in both study groups. CONCLUSIONS: RMS accelerations exhibited good repeatability during walking in healthy and knee OA subjects. The repeatability of EMG measurements was acceptable in healthy subjects depending on the measured muscles.

Microbiological investigations of oxygen plasma treated parylene C surfaces for metal implant coating.

Parylene C surface was modified by the use of oxygen plasma treatment and characterized by microscopic and surface-sensitive techniques (E-SEM, AFM, XPS, LDI-TOF-MS, contact angle). The influence of the treatment on surface properties was investigated by calculations of surface free energy (Owens-Wendt method). Moreover, early adhesion (Culture Plate Method, Optical Microscopy Test) and biofilm formation ability (Cristal Violet Assay) on the parylene C surface was investigated. The bacteria strains which are common causative agents of medical device-associated infections (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa--reference strains and clinical isolates) were used. It was concluded that chemical (oxygen insertion) and physical (nanotopography generation) changes, have a significant impact on the biocompatibility in terms of increased hydrophilicity (θ w of unmodified sample = 88° ± 2°, θ w of 60 min modified sample = 17.6° ± 0.8°) and surface free energy (SFE of unmodified sample = 42.4 mJ/m(2), and for 60 min modified sample = 70.1 mJ/m(2)). At the same time, no statistical effect on biofilm production and bacteria attachment to the modified surface of any of the tested strains was observed.

Prescribing for off-label use and unauthorized medicines in three paediatric wards in Finland, the status before and after the European Union Paediatric Regulation.

WHAT IS KNOWN AND OBJECTIVE: The European Paediatric Regulation aims to reduce off-label use of medicines in paediatric pharmacotherapy. Prescribing for off-label use and unauthorized medicines was common in the paediatric wards of the Kuopio University Hospital in 2001. To evaluate the possible impact of the Regulation on the prevalence and the frequency on such prescribing, we repeated the study in 2011 as it was conducted 10 years earlier. METHODS: In this prospective study, the prescriptions for patients below 18 years of age were reviewed during a 2-week period in each of the three wards; neonatal intensive care unit, general paediatric ward and paediatric surgical ward in April and May 2011. The medicine's authorizing status of all prescriptions was determined according to the approved summary of product characteristics valid during the study in Finland. Data concerning unauthorized medicines were also recorded and classified. RESULTS: Out of the entire study population of 123 patients, 119 received a total of 1054 prescriptions in 2011. The proportion of patients with at least one prescription for off-label use or for an unauthorized medicine was significantly higher, 79% (n = 97) in 2011, compared to 58% in 2001 (P < 0·001). For newborns, significantly more prescriptions were for off-label use in 2011 than in 2001 (51% vs. 22%; P < 0·001). The proportion of prescriptions for unauthorized medicines was significantly higher in children below 2 years of age than in older children in both years (21% vs. 5% in 2011 and 24% vs. 3% in 2001, P < 0·001). WHAT IS NEW AND CONCLUSION: The prescribing for off-label use and unauthorized medicines was more prevalent in 2011 than in 2001. This indicates that the recent legislation has had only minor or no impact on the authorizing status of medicines commonly used in paediatric inpatients in specialized care.

In vitro and in vivo degradation profile of aliphatic polyesters subjected to electron beam sterilization.

Degradation characteristics in response to electron beam sterilization of designed and biodegradable aliphatic polyester scaffolds are relevant for clinically successful synthetic graft tissue regeneration. Scaffold degradation in vitro and in vivo were documented and correlated to the macroscopic structure and chemical design of the original polymer. The materials tested were of inherently diverse hydrophobicity and crystallinity: poly(L-lactide) (poly(LLA)) and random copolymers from L-lactide and ε-caprolactone or 1,5-dioxepan-2-one, fabricated into porous and non-porous scaffolds. After sterilization, the samples underwent hydrolysis in vitro for up to a year. In vivo, scaffolds were surgically implanted into rat calvarial defects and retrieved for analysis after 28 and 91days. In vitro, poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) samples degraded most rapidly during hydrolysis, due to the pronounced chain-shortening reaction caused by the sterilization. This was indicated by the rapid decrease in both mass and molecular weight of poly(LLA-co-DXO). Poly(L-lactide-co-ε-caprolactone) (poly(LLA-co-CL)) samples were also strongly affected by sterilization, but mass loss was more gradual; molecular weight decreased rapidly during hydrolysis. Least affected by sterilization were the poly(LLA) samples, which subsequently showed low mass loss rate and molecular weight decrease during hydrolysis. Mechanical stability varied greatly: poly(LLA-co-CL) withstood mechanical testing for up to 182 days, while poly(LLA) and poly(LLA-co-DXO) samples quickly became too brittle. Poly(LLA-co-DXO) samples unexpectedly degraded more rapidly in vitro than in vivo. After sterilization by electron beam irradiation, the three biodegradable polymers present widely diverse degradation profiles, both in vitro and in vivo. Each exhibits the potential to be tailored to meet diverse clinical tissue engineering requirements.

Time-varying spectrum estimation of heart rate variability signals with Kalman smoother algorithm.

A time-varying parametric spectrum estimation method for analyzing dynamics of heart rate variability (HRV) signals is presented. In the method, HRV signal is first modeled with a time-varying autoregressive model and the model parameters are solved recursively with a Kalman smoother algorithm. Time-varying spectrum estimates are then obtained from the estimated model parameters. The obtained spectrum can be further decomposed into separate components, which is especially advantageous in HRV applications where low frequency (LF) and high frequency (HF) components are generally aimed to be distinguished. As case studies, the dynamics of HRV signals recorded during 1) orthostatic test, 2) exercise test and 3) simulated driving task are analyzed.

Headspace solid-phase microextraction--a tool for new insights into the long-term thermo-oxidation mechanism of polyamide 6.6.

Low-molecular-mass products formed during thermo-oxidation of polyamide 6.6 at 100 degrees C were extracted by headspace solid-phase microextraction and identified by GC-MS. A total of 18 degradation products of polyamide 6.6 were identified. In addition some low-molecular-mass products originating from the lubricants were detected. The identified degradation products were categorized into four groups where compounds within each group contain the same structural feature. In groups A, B and C several new thermo-oxidation products of polyamide 6.6 were identified including cyclic imides, pyridines and structural fragments from the original polyamide chain. 1-Pentyl-2,5-pyrrolidinedione (pentylsuccinimide) showed the largest increase in abundance during oxidation. The cyclopentanones in group D were already present in the un-aged material. Their amounts decreased during ageing and they are thus not formed during thermo-oxidation of polyamide 6.6 at 100 degrees C. The identified thermo-oxidation products can be formed as a result of extensive oxidation of the hexamethylenediamine unit in the polyamide backbone. The degradation products pattern shows that the long-term thermo-oxidative degradation, just like thermal degradation and photo-oxidation of polyamide 6.6, starts at the N-vicinal methylene groups.

Hypermethylation of calcitonin gene regulatory sequences in human breast cancer as revealed by genomic sequencing.

DNA methylation has been studied intensively during the past years in order to elucidate its role in the regulation of gene expression, gene imprinting and cancer progression. Earlier studies have shown that a general genomic under-methylation is associated with chronic lymphocytic leukemia and metastatic prostate cancer. Site-specific methylation changes, as revealed by the use of methylation-sensitive restriction enzymes, have been reported to occur in the promotor region of the calcitonin gene in chronic myeloid leukemia as it progresses from the chronic phase to blast crisis, in non-Hodgkin's lymphoid neoplasms and in non-lymphocytic leukemia. We have now explored possible methylation changes associated with benign and malignant breast tumors. Two approaches were employed: (i) chemical determination of general genomic methylation status and (ii) base-specific analysis of the methylation changes in the promoter of the calcitonin gene with the aid of genomic sequencing. The results did not reveal any changes of total DNA 5-methylcytosine content in ductal carcinoma of breast in comparison with benign tumors. There was a small, yet significant, increase in 5-methylcytosine content in lobular carcinoma. Genomic sequencing of the promoter region of the calcitonin gene, however, revealed a striking hypermethylation at or around the transcription start site of the gene in ductal carcinomas. In benign tumors and lobular carcinomas, this region was either entirely unmethylated or only slightly methylated. The latter changes may reflect a regional hypermethylation of the short arm of chromosome 11, which harbors, in addition to the calcitonin gene, a number of putative or established tumor-suppressor genes. Our results demonstrate that genomic sequencing in its present form can be used for a reliable and precise DNA methylation analysis of primary human tumors.

Carcinoembryonic antigen is expressed on endothelial cells. A putative mediator of tumor cell extravasation and metastasis.

Carcinoembryonic antigen (CEA) is a highly glycosylated cell surface protein. It is produced in large amounts in essentially all colon and several other adenocarcinomas. It has therefore been widely used as a clinical tumor marker. CEA is also a member of the immunoglobulin superfamily. Members of this family, such as ICAM-1, ICAM-2, VCAM-1 and NCAM, are known to participate in cell-cell adhesion. Similarly, the intercellular adhesion properties of CEA have been documented: it has been shown to mediate homotypic adhesion of cultured human colon adenocarcinoma cell lines. In this study we show for the first time that CEA is expressed on cultured human umbilical vein endothelial cells and on the endothelial cell line Ea.hy926. The expression of CEA on cultured endothelial cells can be enhanced by TNF-alpha or IFN-gamma, and decreased by IL-4. We demonstrate using immunohistochemistry that anti-CEA monoclonal antibody reacted with FVIII-positive endothelium in tissue sections prepared from lymph nodes. Finally, we were able to show that CEA-positive breast carcinoma cells bind to purified CEA protein, whereas CEA-negative breast carcinoma cells do not. These results reveal for the first time that endothelial cells express CEA on the cell surface and suggest that CEA-expressing adenocarcinomas could adhere to endothelial cells via CEA-CEA interaction, thus facilitating tumor cell extravasation and hematogenic metastasis.

Down-regulation of monocytic VLA-4 leads to a decreased adhesion to VCAM-1.

The alpha 4 beta 1 integrin VLA-4 is expressed on practically all leukocytes, except on mature granulocytes. Here we show that in vitro treatment of monocytic cells with phorbol-12-myristate-13-acetate (PMA) leads to a selective decrease in the VLA-4 alpha-chain expression, both at the RNA and protein level. Meanwhile the expression of beta 1 and that of alpha 5, another alpha-chain associating with beta 1, was seen to increase. The decrease of alpha 4 expression was restricted to monocytic cells, and was not observed on other VLA-4-positive cells tested (MOLT-4 T cells and HOS sarcoma cells). The down-regulation of the VLA-4 alpha-chain was followed by a decreased binding capacity of the cells to recombinant VCAM-1. This data indicates that while previous findings show that the integrin-dependent adhesion may rapidly be regulated by altering the avidity of the interacting molecules, their quantitative modulation also has a clear impact on adhesion.