Temporal changes in foveal contour after macular hole surgery

BACKGROUND

To investigate the changes in inner foveal contour after surgery for macular hole (MH) and its clinical implications.

METHODS

This retrospective observational case series included 66 eyes from 66 patients who underwent surgery for MH. Notching of tissue was defined as an abrupt alteration in the inner contour of the parafoveal tissue based on postoperative optical coherence tomography (OCT) image. The distance between the parafoveal edges of the outer plexiform layer (OPL) was defined as the inter-OPL distance. The inter-OPL distance was divided into nasal, temporal, superior, and inferior lengths. The difference in the lengths of each direction between the early and late postoperative period was compared between directions with and without notching.

RESULTS

The early and late postoperative examination was performed at 4.6±2.9 weeks and 6.2±0.6 months, respectively. Notching of tissue was noted in 54 eyes (81.8%). In 53 eyes with a measurable inter-OPL distance, the notching of tissue was noted in 45 eyes (84.9%) regardless of preoperative MH size. The mean amount of foveal tissue elongation that occurred during the designated period was 104.6±68.8 and 78.4±72.9 μm in the directions with and without the notching of tissue (P<0.001), respectively.

CONCLUSIONS

The changes in the inner foveal contour, including notching of tissue and elongation of foveal tissue, were noted in the majority of eyes after MH surgery. Notching of tissue on OCT image could be a clinical marker for the development of foveal tissue elongation after MH surgery.

Heterogeneity of intrinsic biophysical properties among cochlear nucleus neurons improves the population coding of temporal information

Reliable representation of the spectrotemporal features of an acoustic stimulus is critical for sound recognition. However, if all neurons respond with identical firing to the same stimulus, redundancy in the activity patterns would reduce the information capacity of the population. We thus investigated spike reliability and temporal fluctuation coding in an ensemble of neurons recorded in vitro from the avian auditory brain stem. Sequential patch-clamp recordings were made from neurons of the cochlear nucleus angularis while injecting identical filtered Gaussian white noise currents, simulating synaptic drive. The spiking activity in neurons receiving these identically fluctuating stimuli was highly correlated, measured pairwise across neurons and as a pseudo-population. Two distinct uncorrelated noise stimuli could be discriminated using the temporal patterning, but not firing rate, of the spike trains in the neural ensemble, with best discrimination using information at time scales of 5-20 ms. Despite high cross-correlation values, the spike patterns observed in individual neurons were idiosyncratic, with notable heterogeneity across neurons. To investigate how temporal information is being encoded, we used optimal linear reconstruction to produce an estimate of the original current stimulus from the spike trains. Ensembles of trains sampled across the neural population could be used to predict >50% of the stimulus variation using optimal linear decoding, compared with ∼20% using the same number of spike trains recorded from single neurons. We conclude that heterogeneity in the intrinsic biophysical properties of cochlear nucleus neurons reduces firing pattern redundancy while enhancing representation of temporal information.

Cell patterning with mucin biopolymers

The precise spatial control of cell adhesion to surfaces is an endeavor that has enabled discoveries in cell biology and new possibilities in tissue engineering. The generation of cell-repellent surfaces currently requires advanced chemistry techniques and could be simplified. Here we show that mucins, glycoproteins of high structural and chemical complexity, spontaneously adsorb on hydrophobic substrates to form coatings that prevent the surface adhesion of mammalian epithelial cells, fibroblasts, and myoblasts. These mucin coatings can be patterned with micrometer precision using a microfluidic device, and are stable enough to support myoblast differentiation over seven days. Moreover, our data indicate that the cell-repellent effect is dependent on mucin-associated glycans because their removal results in a loss of effective cell-repulsion. Last, we show that a critical surface density of mucins, which is required to achieve cell-repulsion, is efficiently obtained on hydrophobic surfaces, but not on hydrophilic glass surfaces. However, this limitation can be overcome by coating glass with hydrophobic fluorosilane. We conclude that mucin biopolymers are attractive candidates to control cell adhesion on surfaces.

Probiotic-mediated competition, exclusion and displacement in biofilm formation by food-borne pathogens

The objective of this study was to examine the inhibitory effect of probiotic strains on pathogenic biofilm formation in terms of competition, exclusion and displacement. Probiotic strains (Lactobacillus acidophilus KACC 12419, Lact. casei KACC 12413, Lact. paracasei KACC 12427 and Lact. rhamnosus KACC 11953) and pathogens (Salmonella Typhimurium KCCM 40253 and Listeria monocytogenes KACC 12671) were used to evaluate the auto-aggregation, hydrophobicity and biofilm formation inhibition. The highest auto-aggregation abilities were observed in Lact. rhamnosus (17·5%), Lact. casei (17·2%) and Lact. acidophilus (15·1%). Salm. Typhimurium had the highest affinity to xylene, showing the hydrophobicity of 53·7%. The numbers of L. monocytogenes biofilm cells during the competition, exclusion and displacement assays were effectively reduced by more than 3 log when co-cultured with Lact. paracasei and Lact. rhamnosus. The results suggest that probiotic strains can be used as alternative way to effectively reduce the biofilm formation in pathogenic bacteria through competition, exclusion and displacement.

Endoscopic focal modulation microscopy

We present endoscopic focal modulation microscopy (FMM) for minimally invasive imaging of deep tissue with high contrast, and then compare the results using endoscopic confocal microscopy (CM). Deep tissue imaging is achieved using a needle-like endoscopic probe based on gradient-index (GRIN) lenses. A tissue-like phantom with fluorescent micro-beads and rat kidney tubules were imaged through the endoscopic probe with FMM. FMM effectively rejected the background signals from the out-of-focus plane, thereby enhancing the image contrast and the optical sectioning ability. The combination of the GRIN endoscopic probe and FMM provides deep tissue imaging with better contrast than endoscopic CM.

Heterotopic ossification after central nervous system trauma: A current review

Neurogenic heterotopic ossification (NHO) is a disorder of aberrant bone formation affecting one in five patients sustaining a spinal cord injury or traumatic brain injury. Ectopic bone forms around joints in characteristic patterns, causing pain and limiting movement especially around the hip and elbow. Clinical sequelae of neurogenic heterotopic ossification include urinary tract infection, pressure injuries, pneumonia and poor hygiene, making early diagnosis and treatment clinically compelling. However, diagnosis remains difficult with more investigation needed. Our pathophysiological understanding stems from mechanisms of basic bone formation enhanced by evidence of systemic influences from circulating humor factors and perhaps neurological ones. This increasing understanding guides our implementation of current prophylaxis and treatment including the use of non-steroidal anti-inflammatory drugs, bisphosphonates, radiation therapy and surgery and, importantly, should direct future, more effective ones.

Probiotic-mediated competition, exclusion and displacement in biofilm formation by food-borne pathogens

The objective of this study was to examine the inhibitory effect of probiotic strains on pathogenic biofilm formation in terms of competition, exclusion and displacement. Probiotic strains (Lactobacillus acidophilus KACC 12419, Lact. casei KACC 12413, Lact. paracasei KACC 12427 and Lact. rhamnosus KACC 11953) and pathogens (Salmonella Typhimurium KCCM 40253 and Listeria monocytogenes KACC 12671) were used to evaluate the auto-aggregation, hydrophobicity and biofilm formation inhibition. The highest auto-aggregation abilities were observed in Lact. rhamnosus (17·5%), Lact. casei (17·2%) and Lact. acidophilus (15·1%). Salm. Typhimurium had the highest affinity to xylene, showing the hydrophobicity of 53·7%. The numbers of L. monocytogenes biofilm cells during the competition, exclusion and displacement assays were effectively reduced by more than 3 log when co-cultured with Lact. paracasei and Lact. rhamnosus. The results suggest that probiotic strains can be used as alternative way to effectively reduce the biofilm formation in pathogenic bacteria through competition, exclusion and displacement.

Soluble expression of OmpA from Haemophilus parasuis in Escherichia coli and its protective effects in the mouse model of infection

Haemophilus parasuis causes contagious porcine Glässer's disease leading to severe losses in the swine industry. In this study, we established an efficient Escherichia colibased system for the expression of H. parasuis major outer-membrane protein (MOMP) that has been known as a good vaccine candidate against Glässer's disease. Use of an E. coli-derived pelB leader sequence made it possible to produce recombinant MOMP (rMOMP) as the soluble forms without an additional refolding process. Using two different animal models, it was evaluated that the rMOMP was capable of inducing a significant immune response and providing protection against H. parasuis infection.

Gamma-aminobutyric acid production using immobilized glutamate decarboxylase followed by downstream processing with cation exchange chromatography

We have developed a gamma-aminobutyric acid (GABA) production technique using his-tag mediated immobilization of Escherichia coli-derived glutamate decarboxylase (GAD), an enzyme that catalyzes the conversion of glutamate to GABA. The GAD was obtained at 1.43 g/L from GAD-overexpressed E. coli fermentation and consisted of 59.7% monomer, 29.2% dimer and 2.3% tetramer with a 97.6% soluble form of the total GAD. The harvested GAD was immobilized to metal affinity gel with an immobilization yield of 92%. Based on an investigation of specific enzyme activity and reaction characteristics, glutamic acid (GA) was chosen over monosodium glutamate (MSG) as a substrate for immobilized GAD, resulting in conversion of 2.17 M GABA in a 1 L reactor within 100 min. The immobilized enzymes retained 58.1% of their initial activities after ten consecutive uses. By using cation exchange chromatography followed by enzymatic conversion, GABA was separated from the residual substrate and leached GAD. As a consequence, the glutamic acid was mostly removed with no detectable GAD, while 91.2% of GABA was yielded in the purification step.

Electrical characteristics of 2D and 3D microelectrodes for high-resolution retinal prostheses

In order to provide high quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrode should be large. As the number of microelectrode is increased, the dimension of the microelectrode is decreased, which in turn results in the increased interface impedance of microelectrode and decreased dynamic range of injection current. In addition, the reduced maximum limit of injection current may not be sufficiently large to stimulate the ganglion cells in a retina. In order to improve the trade-off envelope between number of microelectrode and current injection limit, a 3D microelectrode structure can be used as an alternative. From the advancement of microfabrication technology, the fabrication of highly-accurate 3D structures with small dimensions is possible. This paper presents a first comprehensive electrical characterization of 2D and 3D microelectrodes for high-resolution retinal prostheses. Microelectrodes which differ in shapes and diameters are analyzed. Their interface impedances and charge injection limits are quantitatively analyzed. This research can be used to define requirements for further retinal prosthetic device research.