Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds

This paper provides an extensive overview of published studies on the development and applications of three-dimensional bone tissue engineering (TE) scaffolds with potential capability for the controlled delivery of therapeutic drugs. Typical drugs considered include gentamicin and other antibiotics generally used to combat osteomyelitis, as well as anti-inflammatory drugs and bisphosphonates, but delivery of growth factors is not covered in this review. In each case reviewed, special attention has been given to the technology used for controlling the release of the loaded drugs. The possibility of designing multifunctional three-dimensional bone TE scaffolds for the emerging field of bone TE therapeutics is discussed. A detailed summary of drugs included in three-dimensional scaffolds and the several approaches developed to combine bioceramics with various polymeric biomaterials in composites for drug-delivery systems is included. The main results presented in the literature are discussed and the remaining challenges in the field are summarized with suggestions for future research directions.     

Relationships between microstructure and transport properties of proton-conducting porous PVDF membranes

Fluorinated polymers are today investigated as possible alternatives to Nafion™ in PEM Fuel Cells. In this paper, we study the relationships between the microstructure and the proton transport of porous PVDF homopolymer membranes swollen by 11 M aqueous solution of H₃PO₄. The analysis is performed on membranes with different nominal pores size values, d_p. The membranes are thermally stable at least up to 250 °C. A dependence of the proton transport on the pores size has been found, that is particularly evident for low d_p values and at low relative humidity (R.H.). Conductivity values exceeding 0.1 S cm⁻¹ are obtained at 80 °C even at 10% R.H. for d_p ≥ 0.22 μm. We show that the behaviour of the transport properties cannot be simply rationalized in terms of d_p, but it requires an accurate knowledge of the membrane microstructure (tortuosity, pores interconnections and size distributions). ³¹P NMR spectroscopy also shows that anisotropic interactions take place between the components of the solution and at a lower extent, between the solution and the pores walls, also for d_p values in the micrometer range. In order to make a preliminary check of the suitability of these membranes for applications in Direct Methanol Fuel Cells (DMFCs), studies of methanol crossover and diffusion through the membrane have been carried out and compared with those of Nafion™.     

The role of environmental factors and medium composition on bacteriocin-like inhibitory substances (BLIS) production by Enterococcus mundtii strains

Bacteriocin-like inhibitory substances (BLIS)-producers Enterococcus mundtii WGWT1-1A, WGW11.2, WGJ20.1, WGJ40.2 and WGK53 from raw material origin were subjected to a study for the characterization of antimicrobial compound production under several growth conditions, including different cultivation media, growth temperatures, pHs, different concentrations and sources of nitrogen compounds, carbohydrates and other nutritional factors, and in the presence of different percentages of ethanol and NaCl. The five E. mundtii strains showed different behaviors. However, in all cases, MRS and sour dough bacteria (SDB) were found as the optimal media for BLIS production. In general, the higher BLIS production was observed with pH in the range 6.0-8.0 and, except 45 degrees C, the temperature did not show a defining effect. Low or no BLIS activity was detected after growth without nitrogen sources and carbohydrates. Absence of Tween 80, triammoniun citrate, K2HPO4, MgSO4 and MnSO4 did not affect BLIS activity levels. Except for a strain (WGWT1-1A), ethanol did not play a negative role in BLIS expression, while NaCl determined decrease of BLIS activity, proportional with concentration. The above strains did not contain plasmids, hence, BLIS expression is encoded by chromosomal DNA.     

Monitoring combustion unstable dynamics by means of control charts

Thermoacoustic instabilities in combustion chambers represent a serious threat to combustion systems, which can lead to performance degradation as well as to relevant structural damages. The nonlinearity of these phenomena represents a serious obstacle to the prediction of the evolution of the relevant system variables. The early prediction of out-of-control states in combustion chambers might represent an important step ahead in the design of accurate control system for the suppression of undesired behaviours. This study proposes the application of control charts to the prediction of out-of-control states in an experimental combustion chamber. EWMA control charts have been used because they are very useful when on line single measurements are collected from the process. In order to deal with the high level of autocorrelation characterising the deterministic nonlinear experimental measurement, the EWMA control charts have been applied to the residuals of an input–output NARMAX identification model, implemented by means of a Multilayer Perceptron artificial neural network. Obtained results show the ability of the control charts in detecting unstable combustion phenomena, pointing out the promising application of these statistical tools in the diagnostic of combustion instabilities.     

Low-density lipoproteins are more electronegatively charged in type 1 than in type 2 diabetes mellitus

Multifactorial etiology is involved in premature atherosclerosis related to diabetes. Most of the mechanisms that are responsible for the etiology in diabetes have remained unsolved so far. Type 1 diabetes is associated with a favorable lipid pattern and with microangiopathy, which is not true for type 2 diabetes, which is related to dyslipidemia and macroangiopathy. The aim of this work was to evaluate the degree of LDL modification related to the types of diabetes. The question is whether the LDL could be differently modified since the pathogenesis of type 1 and type 2 diabetes is different. Thirtyone type 1 (19 male and 12 female) and thirty type 2 (18 male and 12 female) diabetic patients were included in this study. Isolated LDL was analyzed by capillary electrophoresis for diene conjugate content and for electronegativity. LDL from type 1 diabetes subjects showed the highest electrophoretic mobility (P=0.000). Instead, the diene conjugates contents were higher in the type 2 patients with HbA1c levels >8% (P=0.007). In conclusion, the increased diene content in type 2 diabetic subjects in poor glycemic control and the highest LDL mobility found in type 1 subjects show that the LDL undergoes different modifications. In type 2 patients, electronegative LDL are in a state of higher susceptibility to oxidation, whereas in type 1 subjects the finding of electronegative lipoproteins could provide an index of the relative atherogenicity of circulating LDL, especially as LDL has higher electrophoretic mobility than normal subjects.