Timeline to dysphagia resolution after endoscopic intervention of an interarytenoid defect based on Video Fluoroscopic Swallow Study dysphagia severity

INTRODUCTION

We previously reported that endoscopic repair of a Type 1 Laryngeal Cleft (LC1) or Deep Interarytenoid Groove (DIG) improves swallowing function postoperatively. However, caregivers often ask about the timeline to resolution of the need for thickening. This study re-examines this cohort to answer this important caregiver-centered question.

METHODS

We reassessed a 3-year retrospective, single-center dataset of children with dysphagia found to have a LC-1 or DIG on endoscopic exam. The primary outcome was rate of complete resolution of dysphagia at 2, 6, and 12 months after endoscopic intervention. A sub-group analysis was made based on severity of dysphagia prior to intervention and by type of endoscopic repair.

RESULTS

Thirty-nine patients with mean age 1.35 years that had a LC-1 or DIG met criteria for inclusion. Rate of complete dysphagia resolution increased over time. Those with mild dysphagia (flow-reducing nipple and/or IDDSI consistency 1 or 2) had brisker resolution than those with moderate dysphagia (IDDSI consistency 3 or 4) at 2 months (67% vs 5%, p < 0.01) and at 6 months (80% vs 18%, p < 0.01) after endoscopic repair. There was no difference in dysphagia resolution between patients grouped by type of endoscopic repair.

CONCLUSION

Addressing an interarytenoid defect in patients will not result in immediate, complete dysphagia resolution in most patients. However, patients that only require a flow-reducing nipple and/or thickening to an IDDSI consistency 1 or 2 have brisker resolution of the need for thickening than those that require an IDSSI consistency 3 or 4 prior to intervention. These results inform pre-operative discussions of the timeline to resolution based upon severity of dysphagia and help manage caregiver expectations.

Longitudinal Exposure-Response Modeling of Multiple Indicators of Alzheimer's Disease Progression

BACKGROUND

Progression in Alzheimer's disease manifests as changes in multiple biomarker, cognitive, and functional endpoints. Disease progression modeling can be used to integrate these multiple measures into a synthesized metric of where a patient lies within the disease spectrum, allowing for a more dynamic measure over the range of the disease.

OBJECTIVES

This study aimed to combine modeling techniques from psychometric research (e.g., item response theory) and pharmacometrics (e.g., hierarchical models) to describe the multivariate longitudinal disease progression for patients with mild-to-moderate Alzheimer's disease. Additionally, we aimed to extend the subsequent model to make it suitable for clinical trial simulation, with the inclusion of covariates, to explain variability in latent progression (i.e., disease progression) and to aid in the assessment of enrichment strategies.

DESIGN

Multiple longitudinal endpoints in the Alzheimer's Disease Neuroimaging Initiative database were modeled. This model was validated internally using visual predictive checks, and externally by comparing data from the placebo arms of two Phase 2 crenezumab studies, ABBY (NCT01343966) and BLAZE (NCT01397578).

SETTING

The Alzheimer's Disease Neuroimaging Initiative began in 2004: the initial 5-year study (ADNI-1) was extended by 2 years in 2009 by a Grand Opportunities grant (ADNI-GO), and in 2011 and 2016 by further competitive renewals of the ADNI-1 grant (ADNI-2 and ADNI-3, respectively). This work studies natural progression data from patients with confirmed Alzheimer's disease. The Phase 2 ABBY and BLAZE trials evaluated the safety and efficacy of crenezumab in patients with mild-to-moderate Alzheimer's disease.

PARTICIPANTS

From the Alzheimer's Disease Neuroimaging Initiative database, 305 subjects who had a baseline diagnosis of mild-to-moderate Alzheimer's disease were included in modeling. From the ABBY and BLAZE studies, 158 patients were included from the studies' placebo arms.

MEASUREMENTS

Longitudinal cognitive and functional assessments modeled included the Clinical Dementia Rating (both as Sum of Boxes and individual item scores), the Mini-Mental State Examination, the Alzheimer's Disease Assessment Scale - Cognitive Subscale, the Functional Activities Questionnaire, the Montreal Cognitive Assessment, and the Rey Auditory Verbal Learning Test. Also included were the imaging variable fluorodeoxyglucose-positron emission tomography and the following magnetic resonance imaging volumetrics: entorhinal, fusiform, hippocampal, intra-cranial, mid-temporal, ventricular, and whole brain.

RESULTS

Applying item response theory approaches in this longitudinal setting showed clinical assessments informing a common disease scale in the following order (from early disease to late disease): Rey Auditory Verbal Learning Test, Functional Activities Questionnaire, Montreal Cognitive Assessment, Alzheimer's Disease Assessment Scale - Cognitive Subscale 12, Clinical Dementia Rating - Sum of Boxes, and Mini-Mental State Examination. The Clinical Dementia Rating communication and home-and-hobbies items were most informative at earlier disease stages, while memory, orientation, and personal care informed the disease status at later stages. A clinical trial simulation model was developed and accurately described within-sample longitudinal distribution of endpoints. Simplifying the model to use only baseline age, MMSE, and APOEε4 status as predictors, out-of-sample mean progression of ADAS-Cog and CDR Sum of Boxes in the ABBY and BLAZE placebo arms was accurately described; however, the variability in these endpoints was underpredicted and suggests possibility for further model refinement when extrapolating from the ADNI sample to trial data. Clinical trial simulations were performed to exemplify use of the model to investigate hypothetical disease modification effects on the multivariate, longitudinal progression on the Alzheimer's Disease Assessment Scale - Cognitive Subscale and the Clinical Dementia Rating - Sum of Boxes.

CONCLUSIONS

The latent variable structure of item response theory can be extended to capture a variety of scales that are common assessments and indicators of disease status in mild-to-moderate Alzheimer's disease. These models are not intended to support causal inferences, but they do successfully characterize the observed correlation between endpoints over time and result in concise numerical indices of disease status that reflect the totality of evidence from considering the endpoints jointly. As such, the models have utility for a variety of tasks in clinical trial design, including simulation of hypothetical drug effects, interpolation of missing data, and assessment of in-sample information.

The future is now: model-based clinical trial design for Alzheimer's disease

Failures in trials for Alzheimer's disease (AD) may be attributable to inadequate dosing, population selection, drug inefficacy, or insufficient design optimization. The Coalition Against Major Diseases (CAMD) was formed in 2008 to develop drug development tools (DDT) to expedite drug development for AD and Parkinson's disease. CAMD led a process that successfully advanced a clinical trial simulation (CTS) tool for AD through the formal regulatory review process at the US Food and Drug Administration (FDA) and European Medicines Agency (EMA).

A cell simulator platform: the cell collective

Diseases are often a result of multiple malfunctions in complex, nonlinear biological/biochemical networks. As such, these processes are far more complicated to understand because they tend to give rise to functions that are emergent in nature, i.e., higher-level (mal)functions that are more than the sum of their parts. Systems biology provides a new approach to understanding biological systems and diseases from a holistic perspective.

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

Nanopost plasmonic crystals

We describe a class of plasmonic crystal that consists of square arrays of nanoposts formed by soft nanoimprint lithography. As sensors, these structure show somewhat higher bulk refractive index sensitivity for aqueous solutions in the visible wavelength range as compared to plasmonic crystals consisting of square arrays of nanowells with similar dimensions, with opposite trends for the case of surface bound layers in air. Three-dimensional finite-difference time-domain simulations quantitatively capture the key features and assist in the interpretation of these and related results.

Familiarity with and use of accommodations and supports among postsecondary students with mental illnesses

OBJECTIVE

Many persons with serious mental illnesses are interested in pursuing postsecondary education and are doing so in increasing numbers. Accommodations can be essential, but limited research suggests that few formally seek accommodations, although increased efforts to heighten awareness may be changing this. The purpose of this study was to examine whether students with mental illnesses are increasingly aware of, and utilize, accommodations and academic supports and to identify the supports that are most used and perceived to be most helpful.

METHODS

A national Internet survey was conducted from July 2005 to July 2006, resulting in responses from 190 current and 318 former students with mental illnesses.

RESULTS

The study found modest but significant negative correlations between how long ago students left college and their familiarity with accommodations, their request for or receipt of accommodations, and their use of the Office for Students With Disabilities. These results were particularly noticeable when comparing current and former students. Moderate positive correlations that were significant were found between familiarity with accommodations, use of campus disability offices, and request for or receipt of accommodations.

CONCLUSIONS

There is increased awareness and use of accommodations among students with mental illnesses, but it is also clear that most receive supports directly from instructors without going through the formal accommodations process. Encouraging students to utilize disability offices and greater attention to accommodation barriers may further increase support seeking. Supports that are most used and viewed as most helpful provide direction for service providers and campus personnel in their efforts to facilitate students' educational goals.

Barriers to recovery and recommendations for change: the Pennsylvania Consensus Conference on psychiatry's role

OBJECTIVE

Recovery has emerged over the past decade as a dominant theme in public mental health care.

METHODS

The 2006 Pennsylvania Consensus Conference brought together 24 community psychiatrists to explore the barriers they experienced in promoting recovery and their recommendations for change.

RESULTS

Twelve barriers were identified and classified into one of three categories: psychiatry knowledge, roles, and training; the need to transform public mental health systems and services; and environmental barriers to opportunity. Participants made 22 recommendations to address these barriers through changes in policies, programs, and psychiatric knowledge and practice.

CONCLUSIONS

The recommendations identify areas for change that can be accomplished through individual psychiatrist action and organized group efforts.

Experimental and theoretical studies of transport through large scale, partially aligned arrays of single-walled carbon nanotubes in thin film type transistors

Gate-modulated transport through partially aligned films of single-walled carbon nanotubes (SWNTs) in thin film type transistor structures are studied experimentally and theoretically. Measurements are reported on SWNTs grown by chemical vapor deposition with systematically varying degrees of alignment and coverage in transistors with a range of channel lengths and orientations perpendicular and parallel to the direction of alignment. A first principles stick-percolation-based transport model provides a simple, yet quantitative framework to interpret the sometimes counterintuitive transport parameters measured in these devices. The results highlight, for example, the dramatic influence of small degrees of SWNT misalignment on transistor performance and imply that coverage and alignment are correlated phenomena and therefore should be simultaneously optimized. The transport characteristics reflect heterogeneity in the underlying anisotropic metal-semiconductor stick-percolating network and cannot be reproduced by classical transport models.

Activation of alpha7 acetylcholine receptors augments stimulation-induced hippocampal theta oscillation

In the septohippocampal formation alpha7 nicotinic receptors (alpha7 nAChRs) are predominantly expressed by neurons well positioned to modulate hippocampal theta oscillation, such as GABAergic interneurons in the hippocampus, and by both GABAergic and cholinergic septal neurons. In the present experiments, we evaluated the efficacy of the recently developed selective alpha7 nAChR agonist PNU-282987 on hippocampal theta oscillation in anaesthetized rats. This compound shows high affinity for the rat alpha7 nAChRs (Ki = 26 nM) but a negligible activity at other nAChRs. Systemic administration of PNU-282987 significantly enhanced the power (by 40%) of hippocampal theta oscillation induced by electrical stimulation of the brainstem reticular formation. In contrast, the amnesic and muscarinic receptor antagonist scopolamine significantly decreased the power (by 68%) of the stimulation-induced theta oscillation. Given the connection between hippocampal theta oscillation and cognitive processes, it is proposed that precognitive actions of alpha7 nAChR agonists could be mediated, at least in part, by modulation of hippocampal oscillatory activity.

Trisomy of chromosome 18 in the baboon (Papio hamadryas anubis)

Trisomy 18 is usually a lethal chromosomal abnormality and is the second most common autosomal trisomy in humans, with an incidence of 1:8000 live births. It is commonly associated with abnormalities of the lower and upper extremities, having the frequency of 95% and 65%, respectively. A newborn female olive baboon (Papio hamadryas anubis) was diagnosed with intrauterine growth retardation and severe arthrogryposis-like congenital joint deformities. Cytogenetic analysis including G-banding and fluorescence in situ hybridization (FISH) revealed that the congenital abnormalities were associated with chromosomal mosaicism for trisomy 18. Genetic analysis with microsatellites from chromosome 18 confirmed the maternal origin of the extra chromosome 18. This is the first report of trisomy 18 in the baboon, which may be a promising animal model of human disease.

Hall effect in the accumulation layers on the surface of organic semiconductors

We have observed the Hall effect in the field-induced accumulation layer on the surface of single-crystal samples of a small-molecule organic semiconductor rubrene. The Hall mobility muH increases with decreasing temperature in both the intrinsic (high-temperature) and trap-dominated (low-temperature) conduction regimes. In the intrinsic regime, the density of mobile field-induced charge carriers extracted from the Hall measurements, nH, coincides with the density n calculated using the gate-channel capacitance and becomes smaller than n in the trap-dominated regime. The Hall data are consistent with the diffusive bandlike motion of field-induced charge carriers between trapping events.

National Estimates for Mental Health Mutual Support Groups, Self-Help Organizations, and Consumer-Operated Services

The authors report on a 2002 national survey of mental health mutual support groups (MSG) and self-help organizations (SHO) run by and for mental health consumers and/or family members, and consumer-operated services (COS). They found 7,467 of these groups and organizations-3,315 MSGs, 3,019 SHOs, and 1,133 COSs-greatly eclipsing the number of traditional mental health organizations (4,546). MSGs reported that 41,363 people attended their last meetings. SHOs reported a total of 1,005,400 members. COSs reported serving 534,551 clients/members in 1 year. The array of services and supports provided within each of these types (MSG, SHO, COS) is reported, and implications for the President's New Freedom Commission on Mental Health recommendations are explicated.

Intrinsic charge transport on the surface of organic semiconductors

The air-gap field-effect technique enabled realization of the intrinsic (not limited by static disorder) polaronic transport on the surface of rubrene (C42H28) crystals over a wide temperature range. The signatures of this intrinsic transport are the anisotropy of the carrier mobility, mu, and the growth of mu with cooling. Anisotropy of mu vanishes in the activation regime at low temperatures, where the transport is dominated by shallow traps. The deep traps, introduced by x-ray radiation, increase the field-effect threshold without affecting mu, an indication that the filled traps do not scatter polarons.

In-line liquid-crystal microcell polarimeter for high-speed polarization analysis

We report a type of high-speed microcell polarimeter that utilizes microelectrodes, liquid-crystal films, and ultrathin high-contrast polarizers, all integrated between the tips of two optical fibers. When combined with optimized nematic liquid-crystal materials, this compact (2.5 cm x 0.5 cm x 0.5 cm) device offers excellent optical properties and continuous, high-speed operation at > 2 kHz with moderately low operating voltages. It requires no bulk optical elements, and it shows excellent performance when implemented for the measurement of degree of polarization in 10-Gbit/s test systems. Polarimeters based on this design have promising potential applications in polarization analysis for high-speed optical communication systems.

Investigation into the relationship between body surface area and total body potassium using Monte Carlo and measurement

The use of body surface area (BSA) as a means of indexing chemotherapy doses is widespread even though the value of this practice is uncertain. In principle, the body cell mass (BCM) more closely represents the body's metabolic size and this is investigated here as an alternative to BSA; since 98% of body potassium is intracellular the derivation of total body potassium (TBK) via the measurement of 40K in a whole body counter (WBC) will provide a useful normalizing index for metabolic size, potentially avoiding toxicity and underdosing. The Queen Elizabeth Hospital WBC has been used in this study, initially involving single geometrical phantoms and then combinations of these to simulate human body habitus. Monte Carlo N-particle (MCNP) codes were constructed to model the phantoms and simulate the measurements made in the WBC. Efficiency corrections were derived by comparing measurement and modelled data for each detector separately. A method of modelling a person in the WBC as a series of ellipsoids was developed. Twenty-four normal males and 24 females were measured for their 40K emissions. Individual MCNP codes were constructed for each volunteer and the results used in conjunction with the measurements to derive TBK, correcting for body habitus effects and detector efficiencies. An estimate of the component of error arising from sources other than counting statistics was included by analysing data from the measurement of phantoms. The total residual errors (expressed as coefficients of variation) for males and females were 10.1% and 8.5% respectively. The measurement components were determined to be 2.4% and 2.5%, implying that the biological components were 9.8% and 8.1% respectively. These results suggest that the use of BSA for indexing chemotherapy doses is likely to give rise to clinically significant under- or overdosing.

Use of optical coherence tomography for assessment of dental caries: quantitative procedure

A method for quantitative assessment of dental caries using optical coherence tomography (OCT) was demonstrated. Development of caries lesions in 15 bovine teeth, by demineralization in acidic buffer solution, was quantitatively assessed daily for 3 days, using OCT. An OCT system which can collect A-scans (depth versus reflectivity curve), B-scans (longitudinal images) and C-scans (transverse images at constant depth) was used. While the B- and C-scans qualitatively described the lesion detected, the A-scan which showed the depth (mm) resolved reflectivity (dB) of the tooth tissue was used for the quantitative analysis. After a simple normalization procedure to determine the actual depth the light travelled into the tooth tissue, the area (R) under the A-scan was quantified as a measure of the degree of reflectivity of the tissue. The result showed that R (dB mm) decreased with increasing demineralization time. The percentage reflectivity loss (R%) in demineralized tissue, which related to the amount of mineral loss, was also calculated, and it was observed that R% increased with increasing demineralization time. It was concluded that with the above procedure, OCT could quantitatively monitor the mineral changes in a caries lesion on a longitudinal basis.

A confidence-set approach for finding tightly linked genomic regions

As more studies adopt the approach of whole-genome screening, geneticists are faced with the challenge of having to interpret results from traditional approaches that were not designed for genome-scan data. Frequently, two-point analysis by the LOD method is performed to search for signals of linkage throughout the genome, for each of hundreds or even thousands of markers. This practice has raised the question of how to adjust the significance level for the fact that multiple tests are being performed. Various recommendations have been made, but no consensus has emerged. In this article, we propose a new method, the confidence-set approach, that circumvents the need to correct for the level of significance according to the number of markers tested. In the search for the gene location of a monogenic disorder, multiplicity adjustment is not needed in order to maintain the desired level of confidence. For complex diseases involving multiple genes, one needs only to adjust the level of significance according to the number of disease genes--a much smaller number than the number of markers in a genome screen-to ensure a predetermined genomewide confidence level. Furthermore, our formulation of the tests enables us to localize disease genes to small genomic regions, an extremely desirable feature that the traditional LOD method lacks. Our simulation study shows that, for sib-pair data, even when the coverage probability of the confidence set is chosen to be as high as 99%, our approach is able to implicate only the markers that are closely linked to the disease genes.

Paper-like electronic displays: large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks

Electronic systems that use rugged lightweight plastics potentially offer attractive characteristics (low-cost processing, mechanical flexibility, large area coverage, etc.) that are not easily achieved with established silicon technologies. This paper summarizes work that demonstrates many of these characteristics in a realistic system: organic active matrix backplane circuits (256 transistors) for large ( approximately 5 x 5-inch) mechanically flexible sheets of electronic paper, an emerging type of display. The success of this effort relies on new or improved processing techniques and materials for plastic electronics, including methods for (i) rubber stamping (microcontact printing) high-resolution ( approximately 1 microm) circuits with low levels of defects and good registration over large areas, (ii) achieving low leakage with thin dielectrics deposited onto surfaces with relief, (iii) constructing high-performance organic transistors with bottom contact geometries, (iv) encapsulating these transistors, (v) depositing, in a repeatable way, organic semiconductors with uniform electrical characteristics over large areas, and (vi) low-temperature ( approximately 100 degrees C) annealing to increase the on/off ratios of the transistors and to improve the uniformity of their characteristics. The sophistication and flexibility of the patterning procedures, high level of integration on plastic substrates, large area coverage, and good performance of the transistors are all important features of this work. We successfully integrate these circuits with microencapsulated electrophoretic "inks" to form sheets of electronic paper.

Formulation and evaluation of a folic acid receptor-targeted oral vancomycin liposomal dosage form

PURPOSE

To demonstrate utility of folic acid-coated liposomes for enhancing the delivery of a poorly absorbed glycopeptide, vancomycin. via the oral route.

METHODS

Liposomes prepared as dehydration-rehydration vesicles (DRVs) containing vancomycin were optimized for encapsulation efficiency and stability. A folic acid-poly(ethylene oxide)-cholesterol construct was synthesized for adsorption at DRV surfaces. Liposomes were characterized by differential scanning calorimetry (DSC) and assessed in vitro in the Caco-2 cell model and in vivo in male Sprague-Dawley rats. Non-compartmental pharmacokinetic analysis of vancomycin was conducted after intravenous and oral administration of solution or liposome-encapsulated vancomycin with or without 0.05 mole ratio FA-PEO-Chol adsorbed at liposome surfaces.

RESULTS

Optimal loading of vancomycin (32%) was achieved in DRVs of DSPC:Chol:DCP, 3:1:0.25 mole ratio (m.r.) after liposome extrusion. Liposomes released less than 40% of the entrapped drug after 2 hours incubation in simulated gastrointestinal (GI) fluid and simulated intestinal fluid containing a 10 mM bile salt cocktail. Incorporation of FA-PEO-Chol in liposomes increased drug leakage by 20% but resulted in a 5.7-fold increase in Caco-2 cell uptake of vancomycin. Liposomal delivery significantly increased the area under the curve of oral vancomycin resulting in a mean 3.9-fold and 12.5-fold increase in relative bioavailability for uncoated and FA-PEO-Chol-coated liposomes, respectively, compared with an oral solution.

CONCLUSIONS

The design of FA-PEO-Chol-coated liposomes resulted in a dramatic increase in the oral delivery of a moderate-size glycopeptide in the rat compared with uncoated liposomes or oral solution. It is speculated that the cause of the observed effect was due to binding of liposome-surface folic acid to receptors in the GI tract with subsequent receptor-mediated endocytosis of entrapped vancomycin by enterocytes.

Noncontact quantitative spatial mapping of stress and flexural rigidity in thin membranes using a picosecond transient grating photoacoustic technique

This paper describes a purely optical technique for measuring and spatially mapping out stress and rigidity in thin membranes. Its application to a membrane of aluminum nitride that has significant spatial nonuniformities in its elastic properties demonstrates the method. The attractive features of this technique--fast, noncontacting measurement, good spatial resolution, ability to quantify in-plane anisotropy--make it potentially useful for characterizing elements of microelectromechanical structures, masks for advanced lithography systems, acoustic filters, and other devices in which the mechanical properties of membranes are important.

Src homology 2 domain substitution modulates the kinase and transforming activities of the Fes protein-tyrosine kinase

The c-fes proto-oncogene encodes a Mr 93,000 protein-tyrosine kinase (Fes) that is strongly expressed in myeloid cells and has been implicated in myelomonocytic differentiation. Fes autophosphorylation and transforming activity are highly restrained after ectopic expression in fibroblasts, indicating tight negative regulation of Fes kinase activity in vivo. Here we investigated the regulatory role of the Fes Src homology 2 (SH2) domain by producing a series of chimeric constructs in which the Fes SH2 domain was replaced with those of the transforming oncogenes v-Fps and v-Src or by the NH2-terminal SH2 domain of the Ras GTPase-activating protein. Wild-type and chimeric Fes proteins readily underwent tyrosine autophosphorylation in vitro and produced identical cyanogen bromide phosphopeptide cleavage patterns, indicating that the SH2 substitutions did not influence overall kinase activity or autophosphorylation site selection. However, metabolic labeling of Rat-2 fibroblasts expressing each construct showed that only the Fes/Src SH2 chimera was active in vivo. Consistent with this result, the Fes/Src SH2 domain chimera exhibited potent transforming activity in fibroblasts and enhanced differentiation-inducing activity in K-562 myeloid leukemia cells. In addition, the Fes/Src SH2 chimera exhibited constitutive localization to focal adhesions in Rat-2 fibroblasts and induced the attachment and spreading of TF-1 myeloid cells. These data demonstrate a central role for the SH2 domain in the regulation of Fes kinase activity and biological function in vivo.

Characteristics of heat flow in optical fiber devices that use integrated thin-film heaters

We describe the analysis of heat flow in a type of tunable optical fiber grating that uses thin-film resistive heaters microfabricated on the surface of the fiber. The high rate of heat loss from these microstructures and the relatively low thermal diffusivity of the glass yield unusual thermal properties. Approximate one-dimensional analytical calculations capture important aspects of the thermal characteristics of these systems. Comparison with experimental results that we obtained from devices with established designs validates certain features of the computations. This modeling also establishes the suitability of integrated thin-film heaters for several new types of tunable fiber grating devices.

Survival and differentiation of cultured retinal progenitors transplanted in the subretinal space of the rat

We have shown that embryonic retina contains progenitors which display stem cell properties in vitro. These cells are proliferative and in addition to expressing the neuroectodermal marker, nestin, are multipotential. These properties and the fact that the putative stem cells can differentiate as photoreceptors when exposed to conducive environment identify them as a viable transplantation reagents to address degenerative retinal diseases. Here we report the survival and differentiation of cultured retinal progenitors upon subretinal transplantation. The retinal progenitor grafts, either as neural spheres or in the form of dissociated cells, survived without disrupting the morphology and laminar organization of the host retina. They did not form rosettes, the morphological barrier to the reconstruction of the normal anatomy of the retina. In addition, transplanted progenitors expressed photoreceptor-specific markers, suggesting that progenitors have the potential to differentiate as photoreceptors. Our observations suggest that cultured retinal progenitors can be a viable reagents for therapeutic transplantation.

Regulation of c-Fes tyrosine kinase and biological activities by N-terminal coiled-coil oligomerization domains

The cytoplasmic protein-tyrosine kinase Fes has been implicated in cytokine signal transduction, hematopoiesis, and embryonic development. Previous work from our laboratory has shown that active Fes exists as a large oligomeric complex in vitro. However, when Fes is expressed in mammalian cells, its kinase activity is tightly repressed. The Fes unique N-terminal sequence has two regions with strong homology to coiled-coil-forming domains often found in oligomeric proteins. Here we show that disruption or deletion of the first coiled-coil domain upregulates Fes tyrosine kinase and transforming activities in Rat-2 fibroblasts and enhances Fes differentiation-inducing activity in myeloid leukemia cells. Conversely, expression of a Fes truncation mutant consisting only of the unique N-terminal domain interfered with Rat-2 fibroblast transformation by an activated Fes mutant, suggesting that oligomerization is essential for Fes activation in vivo. Coexpression with the Fes N-terminal region did not affect the transforming activity of v-Src in Rat-2 cells, arguing against a nonspecific suppressive effect. Taken together, these findings suggest a model in which Fes activation may involve coiled-coil-mediated interconversion of monomeric and oligomeric forms of the kinase. Mutation of the first coiled-coil domain may activate Fes by disturbing intramolecular coiled-coil interaction, allowing for oligomerization via the second coiled-coil domain. Deletion of the second coiled-coil domain blocks fibroblast transformation by an activated form of c-Fes, consistent with this model. These results provide the first evidence for regulation of a nonreceptor protein-tyrosine kinase by coiled-coil domains.

Dual on-fiber thin-film heaters for fiber gratings with independently adjustable chirp and wavelength

Dual, independently addressable thin-film resistive heaters fabricated in a multilayer geometry on the surface of an optical fiber provide a new, flexible means for thermally tuning the properties of intracore gratings. In particular, control of the current that is applied to each of these heaters permits the chirp and the central wavelength of the grating to be adjusted independently. The designs and simple fabrication procedures for these types of device, the important physics of heat flow in them, and a tunable add-drop filter that demonstrates essential aspects of their operation are described.

Fabrication of photonic crystal lasers by nanomolding of solgel glasses

We demonstrate the formation, in a single process step, of periodic arrays of features of surface relief with submicrometer lateral dimensions in hybrid organic and inorganic solgel glasses by using elastomeric molding techniques. Lasers formed with molded photonic crystal resonators that consist of triangular, square, and honeycomb lattices of cylindrical posts and holes show emission spectra and lasing thresholds that are similar to devices formed by conventional high-resolution photolithographic patterning of thick layers of thermally grown oxide.

Folic acid-PEO-labeled liposomes to improve gastrointestinal absorption of encapsulated agents

The design of targeted oral liposomes is anticipated to improve the systemic delivery of poorly absorbed agents, such as proteins and peptides. A poly(ethylene oxide) (PEO)-folic acid (FA) derivative was prepared and evaluated for improving liposome transport across a model gastrointestinal cell line (Caco-2). FA-PEO-cholesterol (Chol) derivatives were synthesized and adsorbed at liposome surfaces encapsulating Texas Red((R))-Dextran 3000 (TR-dex), a poorly-absorbed, neutral, hydrophilic, large molecular weight (M(w)) marker. Apparent permeabilities (P(app)) of Caco-2 cells to FA-PEO conjugates, TR-dex, uncoated TR-dex liposomes, and FA-coated TR-dex liposomes were compared at 2 h post-administration. Intracellular delivery of TR-dex was detected by fluorescence microscopy. An increase in intracellular accumulation of TR-dex associated with FA-PEO-coated liposomes, but not other formulations, was evidence of the potential of FA-targeted liposomes in the oral delivery of poorly absorbed, large M(w) agents.

In vitro analysis of a mammalian retinal progenitor that gives rise to neurons and glia

In vivo lineage studies have shown that retinal cells arise from multipotential progenitors whose fates are regulated by cell-cell interactions. To understand the mechanism underlying their maintenance and differentiation, we have analyzed the differentiation potential of progenitors derived from embryonic rat retina in vitro. These progenitors proliferate and remain undifferentiated in vitro in the presence of epidermal growth factor (EGF) and display properties similar to stem cells. In addition to expressing nestin, the neuroectodermal stem cell marker, retinal progenitors are multipotential. Upon withdrawal of EGF and addition of serum, the progenitors downregulate the expression of nestin and express cell-type specific markers corresponding to neurons and glia. In addition to expressing cell-type specific markers, retinal progenitors and their progeny could be distinguished on the basis of their distinct voltage gated current profile. A proportion of progenitors is lineage restricted and the fate of these cells can be influenced by the microenvironment, suggesting that stage-specific interactions mediated by the local environment influence the progression of progenitors towards acquisition of differentiated phenotypes.

Preparation and release of ibuprofen from polyacrylamide gels

The conditions of preparation of polyacrylamide (polyAC) gels, the incorporation of ibuprofen (IB), and the kinetics of IB release under various conditions have been evaluated. Transparent, opaque, or elastic gels were prepared depending on the concentration of acrylamide (AC) and the cross-linking agent, N,N'-methylenebisacrylamide (BIS). Release studies in media below pH 5.0 resulted in opaque gels. The kinetics of IB release was a function of the AC, BIS, and the pH of the medium, but the optimum composition, in terms of gel integrity and release characteristics, was 7% AC cross-linked with BIS at a 50:1 ratio. Modulation of the release rate was possible with the incorporation of 10% of certain polymers. The amount of IB that could be incorporated per gram of transparent gel was a function of the amount of polymer initiator N,N,N',N'-tetramethylene diamine (TEMED) used per gram of gel. More than 200 mg of IB could be incorporated per gram of transparent gel by using 100 microliters of TEMED. The release of IB obeyed matrix/swelling-controlled kinetics and 70-80% of the IB was released from gels containing 10 to 40 mg IB per gram of gel in 5 hr at pH 7.4 and 37 degrees C.

Solubilization of liposomes by weak electrolyte drugs. II. Cefotaxime

The solubilization of dimyristoylphosphatidylcholine (DMPC) liposomes by the weak electrolyte drug, cefotaxime (CFX), has been studied as a function of pH, DMPC, temperature, presence of cholesterol (CHOL), and method of liposome preparation. At 7.5 mM CFX the lag time for solubilization increased, the rate of solubilization decreased, and the minimum turbidity reached increased as a function of DMPC at pH 1.0 and 40 degrees C. Solubilization was most pronounced at pHs below the pKa but inhibited at least one pH unit above the pKa. The critical mole ratio of unionized CFX:DMPC, Rec, for solubilization was estimated to be 0.12. Reducing the temperature slowed the rate of solubilization as did the addition of CHOL. Encapsulation of CFX in liposomes did not significantly reduce CFX degradation,. k1 = 0.048 h-1 at 40 degrees C and a complex of DMPC and a degradation product of CFX precipitated as rectangular crystals. As a result, an increase in the turbidity of solubilized systems was observed from about 20 h to 48 h depending on the conditions. Liposomes in the gel state or with at least 20% CHOL did not undergo an apparent reversal of solubilization. It is concluded that the inclusion of weak electrolyte drugs existing predominantly as the unionized species in liquid crystalline state liposomes may undergo a slow solubilization process not necessarily recognized during characterization.

The potential of liposomes in oral drug delivery

Oral liposome drug delivery has been the subject of much cynicism. Results have been quite variable and, for the most part, have not been predicated on specific objectives that would lead to success. Prerequisites are stability in the gastrointestinal environment and binding to specific sites. Transport via paracellular and transcellular routes from normal epithelial tissue or Peyer's patches leads to different outcomes of drug delivery and immunization, respectively. Polymerized, microencapsulated, and polymer-coated liposomes have all increased the potential of oral liposomes. Using targeted liposomes and a greater understanding of their cellular processing will ultimately lead to effective therapies from oral liposomes.

The role of NeuroD as a differentiation factor in the mammalian retina

NeuroD, a vertebrate homolog of Drosophila atonal gene, plays an important role in the differentiation of neuronal precursors (Lee et al., 1995). We have investigated whether NeuroD subserves a similar function in mammalian retinal neurogenesis. Expression of NeuroD is detected in successive stages of retinal neurogenesis and is associated with a differentiating population of retinal cells. The association of NeuroD predominantly with postmitotic precursors in early as well as late neurogenesis suggests that NeuroD expression plays an important role in the terminal differentiation of retinal neurons. The notion is supported by observations that overexpression of NeuroD during late neurogenesis promotes premature differentiation of late-born neurons, rod photoreceptors, and bipolar cells, and that NeuroD can interact specifically with the E-box element in the proximal promoter of the phenotype-specific gene, opsin.

The c-Fes family of protein-tyrosine kinases

The human c-fes protooncogene encodes a protein-tyrosine kinase (c-Fes) distinct from c-Src, c-Abl and other nonreceptor tyrosine kinases. Although originally identified as the cellular homolog of several transforming retroviral oncoproteins, Fes was later found to exhibit strong expression in myeloid hematopoietic cells and to play a direct role in their differentiation. Recent work has shown that Fes exhibits a more widespread expression pattern in both developing and adult tissues, suggesting a general physiological function for this kinase and its closely related homolog, Fer. This review highlights the unique aspects of Fes structure, regulation, and function that set it apart from other tyrosine kinase families.

Optical heterodyne detection of laser-induced gratings

A novel optical arrangement for heterodyne detection of laser-induced gratings based on the use of a phase mask for both excitation and probe beams provides phase stability and control without the need for an active stabilization scheme. The arrangement greatly simplifies the laser-induced grating experiment. The performance of the technique in both transmission and reflection geometries is illustrated through measurements of bulk and surface acoustic waves generated by picosecond laser pulses.

Liposomal formulations of synthetic MUC1 peptides: effects of encapsulation versus surface display of peptides on immune responses

Synthetic human MUC1 peptides are important candidates for therapeutic cancer vaccines. To explore whether a human MUC1 peptide BP25 (STAPPAHGVTSAPDTRPAPGSTAPP) can be rendered immunogenic by incorporation in liposomes, the effects of physical association of the peptide with liposomes on immune responses were investigated. Lipid conjugated and nonconjugated MUC1 peptides were incorporated in liposomes with a composition of distearoylphosphatidylcholine/cholesterol/dimyristoylphosphatidylglyc erol (3:1:0.25, molar ratio) containing monophosphoryl lipid A (1% w/w of the total lipids). Liposomes were characterized for peptide retention by HPLC and for surface peptide display of MUC1 epitopes by flow cytometry. C57BL/6 mice were immunized with lipopeptide alone, peptide mixed with peptide-free liposomes, and peptide associated with liposomes in entrapped or surface-exposed forms. T cell proliferative responses, cytokine patterns, and antibody isotypes were studied. Results showed that immune responses were profoundly influenced by the liposome formulations. Physically associated, either encapsulated or surface-exposed, peptide liposomes elicited strong antigen-specific T cell responses, but not lipopeptide alone or peptide mixed with peptide-free liposomes. Analysis of the cytokines secreted by the proliferating T cells showed a high level of IFN-gamma and undetectable levels of IL-4, indicating a T helper type 1 response. Thus, physical association of the peptide with liposomes was required for T cell proliferative responses, but the mode of association was not critical. On the other hand, the nature of the association significantly affected humoral immune responses. Only the surface-exposed peptide liposomes induced MUC1-specific antibodies. A domination of anti-MUC1 IgG2b over IgG1 (94 versus 6%) was observed. Our results support the hypothesis that different immune pathways are stimulated by different liposome formulations. This study demonstrated that a liposome delivery system could be tailored to induce either a preferential cellular or humoral immune response.

Imaging profiles of light intensity in the near field: applications to phase-shift photolithography

We describe a method of imaging the intensity profiles of light in near-field lithographic experiments directly by using a sensitive photoresist. This technique was applied to a detailed study of the irradiance distribution in the optical near field with contact-mode photolithography carried out by use of elastomeric phase masks. The experimental patterns in the photoresist determined by scanning electron microscopy and atomic force microscopy were compared with the corresponding theoretical profiles of intensity calculated by use of a simple scalar analysis; the two correlate well. This comparison makes it possible to improve the theoretical models of irradiance distribution in the near field. Analysis of the images highlights issues in the experimental design, provides a means for the optimization of this technique, and extends its application to the successful fabrication of test structures with linewidths of ~50 nm.

Activation of STAT3 by the c-Fes protein-tyrosine kinase

STATs (signal transducers and activators of transcription) are transcription factors that contain SH2 domains and are activated by tyrosine phosphorylation, often in response to cytokine stimulation. Recent evidence indicates that the transforming tyrosine kinases encoded by the v-Src, v-Abl, and v-Fps oncogenes can induce STAT activation, suggesting that their normal cellular homologs may contribute to STAT activation under physiological conditions. In this report, we provide direct evidence that c-Fes, the normal human homolog of v-Fps, potently activates STAT3. Transient transfection of human 293T cells with STAT3 and Fes resulted in strong stimulation of STAT3 DNA binding activity. In contrast, only modest activation of STAT5 by Fes was observed in this system, indicative of possible selectivity. To determine whether Fes-induced STAT3 activation is dependent upon endogenous mammalian kinases, co-expression studies were also performed in Sf-9 insect cells. Fes also induced a dramatic increase in STAT3 DNA binding activity in this system, whereas no activation of STAT5 was observed. As a positive control, both STAT3 and STAT5 were shown to be activated by the Bcr-Abl tyrosine kinase in Sf-9 cells. Fes induced strong tyrosine phosphorylation of STAT3 in both expression systems, consistent with the gel-shift results. Fes and STAT3 have been independently linked to myeloid differentiation. Results presented here suggest that these proteins may cooperate to promote differentiation signaling in response to hematopoietic cytokines.

Wave-front engineering by use of transparent elastomeric optical elements

We describe a class of devices based on elastomeric optical phase gratings. These devices operate by reversibly controlling the phase of transmitted or reflected light by mechanical compression of the transparent elastomer. An optical modulator and an element in an optical display demonstrate two possible applications.

Liposome-associated interferon-alpha-2b functions as an anti-fibrogenic factor for human dermal fibroblasts

This study was conducted to determine whether interferon-alpha-2b (IFN-alpha-2b) can be encapsulated in liposomes without compromising its anti-fibrogenic effects on human dermal fibroblasts. The rationale for this approach is that systemic administration of IFN-alpha-2b by injection for treatment of dermal fibrosis is uncomfortable, requires a large quantity of the cytokine, and cannot be easily used in children. Liposomes are potentially useful as vehicles for the topical delivery of drugs if they can be encapsulated without loss of biologic activity. Empty sonicated vesicles composed of dioleoyl-phosphatidylcholine:dioleoyl-phosphatidylglycerol at a molar ratio of 7:3 were mixed with various concentrations of IFN-alpha-2b and then dried and rehydrated. An enzyme-linked immunosorbent assay (ELISA) was used to determine the efficiency of encapsulation and the stability of the preparation under experimental conditions. Greater than 80% of added IFN-alpha-2b became associated with the liposomes and remained encapsulated for up to 5 d at 4 degrees C. The rate of release increased markedly at 37 degrees C. Liposome-encapsulated IFN-alpha-2b (2000 units per ml) significantly reduced the proliferation of dermal fibroblasts (60 +/- 8.8 vs. 100 +/- 8, mean +/- SEM, p < 0.05, n = 8) and the levels of mRNA for type I (41.5 +/- 8.7% vs 100 +/- 18, p < 0.05, n = 4) and type III (68 +/- 8.4% vs 100 +/- 4.9%, p < 0.05, n = 3) procollagen, as analyzed on northern blots. This was consistent with the reduction found in collagen in conditioned medium from treated fibroblasts. In contrast, treatment increased levels of mRNA for collagenase (241 +/- 42% vs 100 +/- 3.4, p < 0.05, n = 3) and collagenase activity (289 +/- 5.8% vs 100 +/- 10.9%, p < 0.05, n = 9) in conditioned medium. This last effect was probably not due to a reduction in TIMP-1 (tissue inhibitor of metalloproteinase-1) because levels of mRNA for this inhibitor were not lower in treated cells. The efficacy of liposome-associated IFN-alpha-2b in vitro supports the concept of the topical use of this anti-fibrogenic agent for treatment of fibroproliferative disorders.

An interfacial tension model of the interaction of water-soluble polymers with phospholipid composite monolayers

The axi-symmetric drop-shape analysis-pendant drop technique has been used to measure interfacial tension at the chlorobenzene-water interface in the presence of adsorbed films of dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), DMPC-cholesterol, DPPC-cholesterol, DMPC-cholesterol-dicetyl phosphate (DCP) and DPPC-cholesterol-DCP. A surface-pressure function, pi * = pi lipid-polymer -pi lipid (where pi lipid is the surface pressure of the mono-layer without polymer and pi lipid-polymer is the surface pressure of the lipid mono-layer and adsorbed polymer at equilibrium at the chlorobenzene-water interface) was used to characterize the interaction of eight water-soluble polymers with the lipid films. The equation, delta pi * = pi II*-pi I* (where the subscripts II and I denote the higher and lower lipid composites, respectively) was used to determine the differential effect of cholesterol and DCP on mono-layer characteristics in the presence of 1% w/v polymer. Cholesterol or polymer individually condensed DMPC films and expanded DPPC films. However, composite films of DMPC-cholesterol-DCP and carboxymethylchitin (CM-chitin), poly(acrylic acid) (PAA) or poly(vinyl alcohol) (PVA) were more expanded than DMPC films whereas composite films of DPPC were neither more condensed nor expanded than DPPC films. A polymer impact ratio, P* = pi lipid-polymer/pi lpolymer was calculated and the polymers were ranked in order of their impact on the lipid film. PVA and polysaccharides gave low and high P* values, respectively, corresponding to high and low levels of film interaction, whereas PAA and hydrophobized polysaccharides gave intermediate values, indicating their affinity for and penetration of interfacial films with little disruption of the mono-layer. The results show that measurement of interfacial pressures at the chlorobenzene-water interface might be advantageous for evaluating the action of polymers on biological membranes.

Elastomeric diffraction gratings as photothermal detectors

A photothermal detector consisting of a relief grating on the surface of an elastomer was fabricated and characterized. The detector has a sensitivity of the order of microwatts per square millimeter and has rise and fall times of the order of tens of seconds. Numerical and analytical modeling account for the behavior of the detector.

Complex Optical Surfaces Formed by Replica Molding Against Elastomeric Masters

Complex, optically functional surfaces in organic polymers can be fabricated by replicating relief structures present on the surface of an elastomeric master with an ultraviolet or thermally curable organic polymer, while the master is deformed by compression, bending, or stretching. The versatility of this procedure for fabricating surfaces with complex, micrometer- and submicrometer-scale patterns was demonstrated by the production of (i) diffraction gratings with periods smaller than the original grating; (ii) chirped, blazed diffraction gratings (where the period of a chirped grating changes continuously with position) on planar and curved surfaces; (iii) patterned microfeatures on the surfaces of approximately hemispherical objects (for example, an optical surface similar to a fly's eye); and (iv) arrays of rhombic microlenses. These topologically complex, micropatterned surfaces are difficult to fabricate with other techniques.

Autophosphorylation of the Fes tyrosine kinase. Evidence for an intermolecular mechanism involving two kinase domain tyrosine residues

The human c-fes proto-oncogene encodes a cytoplasmic tyrosine kinase (Fes) that is associated with multiple hematopoietic cytokine receptors. Fes tyrosine autophosphorylation sites may regulate kinase activity and recruit downstream signaling proteins with SH2 domains. To localize the Fes autophosphorylation sites, full-length Fes and deletion mutants lacking either the unique N-terminal or SH2 domain were autophosphorylated in vitro and analyzed by CNBr cleavage. Identical phosphopeptides of 10 and 4 kDa were produced with all three proteins, localizing the tyrosine autophosphorylation sites to the C-terminal kinase domain. Substitution of kinase domain tyrosine residues 713 or 811 with phenylalanine resulted in a loss of the 10- and 4-kDa phosphopeptides, respectively, identifying these tyrosines as in vitro autophosphorylation sites. CNBr cleavage analysis of Fes isolated from 32PO4-labeled 293T cells showed that Tyr-713 and Tyr-811 are also autophosphorylated in vivo. Mutagenesis of Tyr-713 reduced both autophosphorylation of Tyr-811 and transphosphorylation of Bcr, a recently identified Fes substrate, supporting a major regulatory role for Tyr-713. Wild-type Fes transphosphorylated a kinase-inactive Fes mutant on Tyr-713 and Tyr-811, suggesting that Fes autophosphorylation occurs via an intermolecular mechanism analogous to receptor tyrosine kinases.

Formulation and release kinetics of cephalexin monohydrate from biodegradable polymeric microspheres

Sustained release cephalexin microspheres have been formulated with poly(L-lactic acid) for intraperitoneal administration. Microspheres were prepared with spray-dried cephalexin by phase separation in organic solvent containing a fixed concentration of polymer, then sieve-sized. Batch-to-batch reproducibility of microsphere size distribution and encapsulation efficiency ( > 95%) were demonstrated. The quality of the microspheres was dependent on the rate of stirring during preparation and was highest as 400 rpm. Scanning electron micrographs revealed approximately spherical shapes and porous surfaces. The release of cephalexin followed second order dissolution model kinetics for multiparticulate systems. The apparent second order rate constant, k2, was lowest for the highest sieve-size fraction (250-425 microns) and varied with drug loading reaching a minimum at 33% w/w. A lower molecular weight PLA of 50 000 produced a faster release of cephalexin from microspheres. Cephalexin was released from microspheres for at least 4 h compared to only 10 min for complete dissolution of an equivalent weight of cephalexin powder, indicating sustained release which may be appropriate in treating localized infections.

Efficacy of sustained release ciprofloxacin microspheres against device-associated Pseudomonas aeruginosa biofilm infection in a rabbit peritoneal model

The relative effectiveness of a poly(L-lactic acid) ciprofloxacin hydrochloride (CIP) microsphere formulation (250-425 microns) against peritoneal implanted biofilm of Pseudomonas aeruginosa was investigated in a rabbit model. Correlations between in-vivo CIP pharmacokinetics in peritoneal dialysate and serum after intraperitoneal administration, in-vivo cell counts and rabbit survival rate were obtained. Dialysate and serum concentrations after 12 h (C12h) were greater than those obtained with free drug whereas maximum serum concentrations (Cmax) were lower and the time to reach Cmax(tmax) was longer. A silastic implant device pre-colonised with P. aeruginosa for 2 days was implanted in the rabbit peritoneum, and dialysate with or without drug or microspheres was administered via a catheter. Rabbits receiving no antibiotic and those receiving free drug (10 mg in dialysate) died of peritonitis and septicaemia, whereas all rabbits given CIP microspheres recovered completely from infection. The viable count of P. aeruginosa was markedly reduced or eliminated from the catheter, the device and the peritoneal wall in CIP microsphere-treated rabbits but not in rabbits treated with free drug, as determined from histological and scanning electronmicroscopic evidence. These results demonstrate that sustained release of antibiotics at biofilm eradication concentrations (BEC) is required to treat biofilm infections associated with peritoneal implanted devices.