Development of photochemical method for meniscal repair: a preliminary study

Visible light combined with naphthalimides has previously been shown to catalyze formation of physical bonds in avascular meniscal tissue. The first objective was to modify the existing in vitro testing method (i.e., adhesion testing using lap-jointed slices) to gain more sensitivity in detecting relative bonding strengths among candidate bonding agents. A repeated measures experimental design (RMED) was used to account for variability in properties among bovine menisci and was achieved by testing all treatments/controls on slices from each meniscus. Additionally, to make the method more clinically relevant in modeling a bucket-handle tear, the bovine meniscal slices were cut with collagen fibers parallel to the test slice's length. Peak stress was greater for the complete treatment group (light plus naphthalimide) than for the control or incomplete treatment groups (light only or napthalimide only). The second objective was to perform concentration and photoactivation time dose-response studies. In the concentration dose-response study, peak stress was greater for all treatments when compared with the control but not different among treatment groups; however, there was a trend of increased bonding strength with increased concentration. In the photoactivation time dose-response study, peak stress was greater for all treatments when compared with the control and greater for the 3-min treatment vs. the 6- and 9-min treatments. Peak stress was not different between the longer treatments. The RMED provided increased reproducibility and statistical sensitivity for detecting differences among treatments and will be used to test candidate bonding agents prior to in vivo testing.     

Impedimetric immunosensor for the specific label free detection of ciprofloxacin antibiotic

Impedance spectroscopy approaches combined with the immunosensor technology have been used for the determination of trace amounts of ciprofloxacin antibiotic belonging to the fluoroquinolone family. The sensor electrode was based on the immobilization of anti-ciprofloxacin antibodies by chemical binding onto a poly(pyrrole-NHS) film electrogenerated on a solid gold substrate. The electrode surface was modified by electropolymerization of pyrrole-NHS, antibody grafting and ciprofloxacin immunoreaction. The sensitive steps of surface modification, cyclic voltammetry (CV) and atomic force microscopy (AFM) imaging have been used for electrode surface characterization. The immunoreaction of ciprofloxacin on the grafted anti-ciprofloxacin antibody directly triggers a signal via impedance spectroscopy measurements which allows the detection of extremely low concentration of 10 pg/ml ciprofloxacin.     

Focus: Addiction: A Feasibility Study of Bilateral Anodal Stimulation of the Prefrontal Cortex Using High-Definition Electrodes in Healthy Participants

Transcranial direct current stimulation (tDCS) studies often use one anode to increase cortical excitability in one hemisphere. However, mental processes may involve cortical regions in both hemispheres. This study’s aim was to assess the safety and possible effects on affect and working memory of tDCS using two anodes for bifrontal stimulation. A group of healthy subjects participated in two bifrontal tDCS sessions on two different days, one for real and the other for sham stimulation. They performed a working memory task and reported their affect immediately before and after each tDCS session. Relative to sham, real bifrontal stimulation did not induce significant adverse effects, reduced decrement in vigor-activity during the study session, and did not improve working memory. These preliminary findings suggest that bifrontal anodal stimulation is feasible and safe and may reduce task-related fatigue in healthy participants. Its effects on neuropsychiatric patients deserve further study.     

Characterization of compost produced from separated pig manure and a variety of bulking agents at low initial C/N ratios

The aim of this study was to investigate the composting of separated pig manure solids with or without a variety of bulking agents at a low initial C/N ratio (12.5-23.3). Compost stability was investigated using an oxygen uptake rate (OUR) test and compost maturity was investigated using a germination index test. All treatments showed typical patterns of compost temperature. Temperatures above 60 °C were achieved by Day 2, followed by a thermophilic phase (50-60 °C), which lasted for 1 to 2 weeks followed by a cooling phase. The stability of one of treatments which did not contain any bulking agent - OUR of 25 mmol O₂ kg⁻¹ OM hour⁻¹ - was negatively affected by its initial high water content (69%). The addition of a bulking agent and initial water content below 60% were necessary to compost the separated solid fraction of pig manure at a low initial C/N ratio.     

Quality control in homograft valve processing: when to screen for microbiological contamination?

Human donor heart valves remain essential for many reconstructive heart procedures. Heart valve donations are a scarce resource which must be used efficiently and safely. Infection transmission remains a potential risk with homograft valve use. Early experience with homograft valves identified high rates of microbial contamination at collection and initiated the practise of immersion in an antibiotic cocktail. Many centres rely on the microbiology screening after exposure to the antibiotic cocktail. We in our centre accept or reject valves on the basis of the microbiology screening at the time of collection prior to immersion in antibiotic solution. We wanted to compare our rate of valve discard and the rate of microbial contamination at implant with other centres. Valves are collected for the Irish Heart Valve Tissue Bank through partnership between the National Centre for Cardiothoracic Surgery and the Irish Blood Transfusion Service. Valves are collected in a surgical theatre setting and processed in dedicated section of the Irish Blood Transfusion Board. Tissues are screening for microbiology at collection and also at implantation. A total of 564 human heart valves and valve conduits were processed through the service during the study period. 167 (29.6%) were discarded during the processing and storage stages. The major reason for this in 117 cases was unsatisfactory microbiology on initial tissue screening. Repeat screening of accepted valves at the time of implantation identified positive cultures in only 0.9%. Optimal use of these limited resources is clearly important. However recipient safety remains paramount. One-fifth of collected valves are discarded at the processing stage due to positive microbiology screening. This is a higher rate of discard then other centres which reject 5.6–10% due to positive microbiology. However our rate of contamination at time of implant is lower then the 3% rate reported elsewhere. We are satisfied that our current discard rate, although significant, reflects rigorous quality control and the optimal balance between valve availability and patient safety.     

Mystique is a new insulin-like growth factor-I-regulated PDZ-LIM domain protein that promotes cell attachment and migration and suppresses Anchorage-independent growth

By comparing differential gene expression in the insulin-like growth factor (IGF)-IR null cell fibroblast cell line (R- cells) with cells overexpressing the IGF-IR (R+ cells), we identified the Mystique gene expressed as alternatively spliced variants. The human homologue of Mystique is located on chromosome 8p21.2 and encodes a PDZ LIM domain protein (PDLIM2). GFP-Mystique was colocalized at cytoskeleton focal contacts with alpha-actinin and beta1-integrin. Only one isoform of endogenous human Mystique protein, Mystique 2, was detected in cell lines. Mystique 2 was more abundant in nontransformed MCF10A breast epithelial cells than in MCF-7 breast carcinoma cells and was induced by IGF-I and cell adhesion. Overexpression of Mystique 2 in MCF-7 cells suppressed colony formation in soft agarose and enhanced cell adhesion to collagen and fibronectin. Point mutation of either the PDZ or LIM domain was sufficient to reverse suppression of colony formation, but mutation of the PDZ domain alone was sufficient to abolish enhanced adhesion. Knockdown of Mystique 2 with small interfering RNA abrogated both adhesion and migration in MCF10A and MCF-7 cells. The data indicate that Mystique is an IGF-IR-regulated adapter protein located at the actin cytoskeleton that is necessary for the migratory capacity of epithelial cells.