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Faricimab is a bispecific antibody that acts through dual inhibition of both angiopoietin-2 and vascular endothelial growth factor A. We report primary results of two phase 3 trials evaluating intravitreal faricimab with extension up to every 16 weeks for neovascular age-related macular degeneration (nAMD).TENAYA and LUCERNE were randomised, double-masked, non-inferiority trials across 271 sites worldwide. Treatment-naive patients with nAMD aged 50 years or older were randomly assigned (1:1) to intravitreal faricimab 6·0 mg up to every 16 weeks, based on protocol-defined disease activity assessments at weeks 20 and 24, or aflibercept 2·0 mg every 8 weeks. Randomisation was performed through an interactive voice or web-based response system using a stratified permuted block randomisation method. Patients, investigators, those assessing outcomes, and the funder were masked to group assignments. The primary endpoint was mean change in best-corrected visual acuity (BCVA) from baseline averaged over weeks 40, 44, and 48 (prespecified non-inferiority margin of four letters), in the intention-to-treat population. Safety analyses included patients who received at least one dose of study treatment. These trials are registered with ClinicalTrials.gov (TENAYA NCT03823287 and LUCERNE NCT03823300).Across the two trials, 1329 patients were randomly assigned between Feb 19 and Nov 19, 2019 (TENAYA n=334 faricimab and n=337 aflibercept), and between March 11 and Nov 1, 2019 (LUCERNE n=331 faricimab and n=327 aflibercept). BCVA change from baseline with faricimab was non-inferior to aflibercept in both TENAYA (adjusted mean change 5·8 letters [95% CI 4·6 to 7·1] and 5·1 letters [3·9 to 6·4]; treatment difference 0·7 letters [-1·1 to 2·5]) and LUCERNE (6·6 letters [5·3 to 7·8] and 6·6 letters [5·3 to 7·8]; treatment difference 0·0 letters [-1·7 to 1·8]). Rates of ocular adverse events were comparable between faricimab and aflibercept (TENAYA n=121 [36·3%] vs n=128 [38·1%], and LUCERNE n=133 [40·2%] vs n=118 [36·2%]).Visual benefits with faricimab given at up to 16-week intervals demonstrates its potential to meaningfully extend the time between treatments with sustained efficacy, thereby reducing treatment burden in patients with nAMD.F Hoffmann-La Roche.

This work addresses the issue of dark states formation in QDs by cooperative excitonic and intrinsic defect-assisted radiative transitions. Here we refer to the observed blinking as D-type to distinguish it from purely excitonic types. It is shown experimentally that defect-assisted radiative relaxations in a single I-III-VI QD result in atypical blinking characteristics that cannot be explained on the basis of charged exciton models. In addition to the excitonic channel, it has been proposed that defect-assisted kinetics can also form blinking patterns. Two conditions for the formation of dark states have been identified which are related to correlation and competition when considering photons emitted from bright defects. Two transition schemes have therefore been proposed. The first transition scheme includes time-correlated trapping of more than one electron at a single trap centre. This is used to simulate variations in the defect's charge state and switching between radiative/nonradiative transitions. The latter scheme, on the other hand, involves uncorrelated trapping and radiative relaxations from two different types of defects (competition). Both schemes are seen to play an equal role in radiative processes in I-III-VI QDs. Considered together, the proposed models can reflect the experimental data with very good accuracy, providing a better understanding of the underlying physics. An important implication of these schemes is that dark states formation doesn't have to be limited to mechanisms that involve charged excitons, and it may also be observed for independent defect assisted kinetics. This is especially valid for highly defected or multinary QDs.

Purpose To evaluate features and outcomes of eyes with retinal vasculitis and intraocular inflammation (IOI) after intravitreal injection (IVI) of brolucizumab 6 mg/0.05 ml for treatment of neovascular age-related macular degeneration. Design Retrospective case series. Participants Fifteen eyes from 12 patients identified from 10 United States centers. Methods Review of patient demographics, ophthalmologic examination results, and retinal imaging findings. Main Outcome Measures Baseline and follow-up visual acuity (VA), prior anti–vascular endothelial growth factor (VEGF) injections, clinical presentation, retinal findings, fluorescein angiography results, and treatment strategies. Results The number of previous anti-VEGF IVIs ranged between 2 and 80 in the affected eye before switching to brolucizumab. Retinal vasculitis and IOI were diagnosed at a mean of 30 days after brolucizumab IVI. Mean VA before brolucizumab IVI was 0.426 logarithm of the minimum angle of resolution (logMAR; Snellen equivalent, 20/53) and VA at diagnosis of retinal vasculitis was 0.981 logMAR (Snellen equivalent, 20/191; range, 20/25–20/1600; P = 0.008). All affected eyes showed IOI with variable combinations of focal or elongated segmental sheathing and discontinuity of small and large retinal arteries, sclerotic arteries, regions of vascular nonperfusion, cotton-wool spots, Kyrieleis plaques, irregular venous caliber with dilated and sclerotic segments, perivenular hemorrhages, and foci of phlebitis. Fluorescein angiography revealed delayed retinal arterial filling, retinal vascular nonperfusion, and variable dye leakage from affected vessels and the optic nerve. Systemic evaluation for embolic causes was unrevealing in 2 patients, and 3 patients showed negative laboratory assessment for uveitis. Treatment consisted of various combinations of corticosteroids (systemic, intravitreal, and topical), and 2 eyes underwent vitrectomy without improvement in vision. After a mean follow-up of 25 days, mean VA was 0.833 logMAR (Snellen equivalent, 20/136), which was reduced compared with baseline (P = 0.033). Conclusions Retinal vasculitis and IOI after brolucizumab IVI are characterized by variable occlusion of large or small retinal arteries, or both, and perivenular abnormalities. It may span from peripheral vasculitis to occlusion of large retinal arteries around the optic nerve or macula with severe vision loss. A high index of suspicion is required because vitreous cells may obscure visualization of retinal details.

We examined the effect of the differences in spatial arrangement of actin in contracting muscles from the left (LV) and right (RV) ventricles of rabbit heart. Spatial arrangement is a fundamental property of muscle because it reflects the interaction of individual actin molecules with myosin cross-bridges. Macroscopic parameters of contraction, such as maximum tension, speed of shortening or ATPase activity, are unlikely to reveal differences between the ventricles because they are made on whole organs containing trillions of actin and myosin molecules. Averaging the data collected from such a large assembly is likely to conceal small differences. To eliminate complications arising from the differences in the basic myocardial architecture and fiber structures of the ventricles, and to ensure that the molecular crowding influences contraction in the same way as under the in-vivo conditions, we collected data from isolated myofibrils ex-vivo . Control anisotropy experiments revealed that the orientation of actin reflected the orientation of myosin cross-bridges. The results showed that the changes in the distribution of actin induced by the interaction of actin filaments with myosin heads were demonstrated only in LVs, not in RVs. This suggests that both ventricles interact differently with myosin cross-bridges. We think that the stress induced in the thin filaments of LV causes loosening of bonds between actin monomers which leads to greater mobility of actin monomers.

Ternary AgInS2 quantum dots (QDs) have been found as promising cadmium-free, red-shifted, and tunable luminescent bio-probes with efficient Stokes and anti-Stokes excitations and luminescence lifetimes (ca. 100 ns) convenient for time resolved techniques like fluorescence life-time imaging. Although the spectral properties of the AgInS2 QDs are encouraging, the complex recombination kinetics in the QDs being still far from understood, limits their full utility. In this paper we report on a model describing the recombination pathways responsible for large deviations from the first-order decay law observed commonly in the ternary chalcogenides. The presented results were evaluated by means of individual AgInS2 QD spectroscopy aided by first principles calculations including the electronic structure and structural reconstruction of the QDs. Special attention was devoted to study the impact of the surface charge state on the excited state relaxation and effect of its passivation by Zn(2+) ion alloying. Two different blinking mechanisms related to defect-assisted charge imbalance in the QD responsible for fast non-radiative relaxation of the excited states as well as surface recharging of the QD were found as the major causes of deviations from the first-order decay law. Careful optimization of the AgInS2 QDs would help to fabricate new red-shifted and tunable fluorescent bio-probes characterized by low-toxicity, high quantum yield, long luminescence lifetime, and time stability, leading to many novel in vitro and in vivo applications based on fluorescence lifetime imaging (FLIM) and time-gated detection.

OBJECTIVES To determine if mean ultimate strength or failure mechanism differed between comminuted olecranon fractures created at the proximal 25% or 50% of the trochlear notch and fixed with precontoured posterior locking plates (PLPs). METHODS Comminuted osteotomies were created in 10 matched pairs of cadaveric upper extremities at either the proximal 25% or 50% of the trochlear notch after quantitative computed tomography scans were performed to evaluate bone mineral density. Variable-angle olecranon PLPs were fixed to the specimens. The triceps tendon of each specimen was loaded cyclically and then to failure. Comparison of mean force at failure (displacement >2 mm) was performed using the 2-tailed t test. RESULTS There were no significant differences in specimen bone mineral density within matched pairs. Nineteen specimens failed by olecranon bisection fracture in the sagittal plane. Specimens in the 25% osteotomy group failed at lower ultimate forces of 808 N (SD ± 474 N) versus 1058 N (SD ± 480 N) in the 50% osteotomy group (P = 0.044). CONCLUSIONS The ultimate strength of comminuted olecranon fracture fixation with a PLP decreases significantly if the fracture is proximal to the midpoint of the trochlear notch. Fractures proximal to the midpoint of the trochlear notch may benefit from supplemental fixation or suture augmentation to prevent failure, particularly at force ranges higher than those experienced during active elbow range of motion.

The contraction of the right ventricle (RV) expels blood into the pulmonary circulation, and the contraction of the left ventricle (LV) pumps blood into the systemic circulation through the aorta. The respective afterloads imposed on the LV and RV by aortic and pulmonary artery pressures create very different mechanical requirements for the two ventricles. Indeed, differences have been observed in the contractile performance between left and right ventricular myocytes in dilated cardiomyopathy, in congestive heart failure, and in energy usage and speed of contraction at light loads in healthy hearts. In spite of these functional differences, it is commonly believed that the right and left ventricular muscles are identical because there were no differences in stress development, twitch duration, work performance, or power among the RV and LV in dogs. This report shows that on a mesoscopic scale [when only a few molecules are studied (here three to six molecules of actin) in ex vivo ventricular myofibrils], the two ventricles in rigor differ in the degree of orientational disorder of actin within in filaments and during contraction in the kinetics of the cross-bridge cycle.

In this report we describe a preparation of silver wires (SWs) on gold mirrors and its application to surface enhanced fluorescence (SEF) using a new methodology. Silica protected gold mirrors were drop-coated with a solution of silver triangular nanoprisms. The triangular nanoprisms were slowly air-dried to get silver wires that self-assembled on the gold mirrors. Fluorescence enhancement was studied using methyl azadioxatriangulenium chloride (Me-ADOTA · Cl) dye in PVA spin-coated on a clean glass coverslip. New Plasmonic Platforms (PPs) were assembled by placing a mirror with SWs in contact with a glass coverslip spin-coated with a uniform Me-ADOTA · Cl film. It was shown that surface enhanced fluorescence is a real phenomenon, not just an enhancement of the fluorescence signal due to an accumulation of the fluorophore on rough nanostructure surfaces. The average fluorescence enhancement was found to be about 15-fold. The lifetime of Me-ADOTA · Cl dye was significantly reduced (∼ 4 times) in the presence of SWs. Moreover, fluorescence enhancement and lifetime did not show any dependence on the excitation light polarization.

Fluorescent nanodiamonds (FNDs) are one of the new and very promising biocompatible nanomaterials that can be used both as a fluorescence imaging agent and a highly versatile platform for controlled functionalization to target and deliver a wide spectrum of therapeutic agents. Among the remarkable fluorescence properties are excellent photostability, emission between 600-700nm, quantum yield of 1 and moderately long fluorescence lifetimes. However the low absorption cross section of fluorescent (N-V)(-) centers limits FNDs' brightness. In this work we show that an approach based on the Forster resonance energy transfer (FRET) may significantly enhance the fluorescence signal observed from a single ND. We demonstrate that organic dyes (fluorophores) attached to the FND surface can efficiently transfer the excitation energy to (N-V)(-) centers. Multiple dyes positioned in close proximity to the ND facile surface may serve as harvesting antennas transferring excitation energy to the fluorescent centers. We propose that, with the help of some of the functional groups present on the FND surface, we can either directly link flurophores or use scalable dendrimer chemistry to position many organic dyes at a calibrated distance. Also, the remaining multiple functional groups will be still available for particle targeting and drug delivery. This opens a new way for designing a new type of theranostics particles of ultrahigh brightness, high photostability, specific targeting, and high capacity for drug delivery.

Force production in muscle results from ATP-driven cyclic interactions of myosin with actin. A myosin cross bridge consists of a globular head domain, containing actin and ATP-binding sites, and a neck domain with the associated light chain 1 (LC1) and the regulatory light chain (RLC). The actin polymer serves as a “rail” over which myosin translates. Phosphorylation of the RLC is thought to play a significant role in the regulation of muscle relaxation by increasing the degree of skeletal cross-bridge disorder and increasing muscle ATPase activity. The effect of phosphorylation on skeletal cross-bridge kinetics and the distribution of orientations during steady-state contraction of rabbit muscle is investigated here. Because the kinetics and orientation of an assembly of cross bridges (XBs) can only be studied when an individual XB makes a significant contribution to the overall signal, the number of observed XBs was minimized to ∼20 by limiting the detection volume and concentration of fluorescent XBs. The autofluorescence and photobleaching from an ex vivo sample was reduced by choosing a dye that was excited in the red and observed in the far red. The interference from scattering was eliminated by gating the signal. These techniques decrease large uncertainties associated with determination of the effect of phosphorylation on a few molecules ex vivo with millisecond time resolution. In spite of the remaining uncertainties, we conclude that the state of phosphorylation of RLC had no effect on the rate of dissociation of cross bridges from thin filaments, on the rate of myosin head binding to thin filaments, and on the rate of power stroke. On the other hand, phosphorylation slightly increased the degree of disorder of active cross bridges.

Fluorescence Correlation Spectroscopy (FCS) is a frequently applied technique that allows for precise and sensitive analyses of molecular diffusion and interactions. However, the potential of FCS for in vitro or ex vivo studies has not been fully realized due in part to artifacts originating from autofluorescence (fluorescence of inherent components and fixative-induced fluorescence). Here, we propose the azadioxatriangulenium (ADOTA) dye as a solution to this problem. The lifetime of the ADOTA probe, about 19.4 ns, is much longer than most components of autofluorescence. Thus, it can be easily separated by time correlated single photon counting (TCSPC) methods. Here, we demonstrate the suppression of autofluorescence in FCS by using ADOTA labeled Hyaluronan macromolecules (HAs) with Rhodamine 123 added to simulate diffusing fluorescent background components. The emission spectrum and decay rate of Rhodamine 123 overlap with the usual sources of autofluorescence, and its diffusion behavior is well known. We show that the contributions from Rhodamine 123 can be eliminated by time-gating or by fluorescence lifetime correlation spectroscopy (FLCS). While the pairing of ADOTA and time-gating is an effective strategy for the removal of autofluorescence from fluorescence imaging, the loss of photons leads to erroneous concentration values with FCS. On the other hand, FLCS eliminates autofluorescence without such errors. We then show that both time gating and FLCS may be used successfully with ADOTA-labeled HA to detect the presence of hyaluronidase, the over-expression of which has been observed in many types of cancer.

Elevated hyaluronidase levels are found in the urine of bladder and prostate cancer patients. Therefore, HA-ase is regarded as an important biomarker for the detection of these cancers. In this report, we use a FRET based ratiometric sensing approach to detect the level of HA-ase in synthetic urine. For this, we have used a HA-FRET probe (hyaluronan) labeled with fluorescein as a donor and rhodamine as an acceptor. We monitor the digestion of our HA-FRET probe with different concentrations of HA-ase in synthetic urine via fluorescence emission. The extent to which FRET is released depends on the concentration of HA-ase. Our fluorescence intensity results are also supported with time resolved fluorescence decay data. This assay can be used to develop a non-invasive technique for the detection of bladder and/or prostate cancer progression.

Calcium binding to thin filaments is a major element controlling active force generation in striated muscles. Recent evidence suggests that processes other than Ca2+ binding, such as phosphorylation of myosin regulatory light chain (RLC) also controls contraction of vertebrate striated muscle (Cooke, R. (2011) Biophys. Rev. 3, 33–45). Electron paramagnetic resonance (EPR) studies using nucleotide analog spin label probes showed that dephosphorylated myosin heads are highly ordered in the relaxed fibers and have very low ATPase activity. This ordered structure of myosin cross-bridges disappears with the phosphorylation of RLC (Stewart, M. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 430–435). The slower ATPase activity in the dephosporylated moiety has been defined as a new super-relaxed state (SRX). It can be observed in both skeletal and cardiac muscle fibers (Hooijman, P., Stewart, M. A., and Cooke, R. (2011) Biophys. J. 100, 1969–1976). Given the importance of the finding that suggests a novel pathway of regulation of skeletal muscle, we aim to examine the effects of phosphorylation on cross-bridge orientation and rotational motion. We find that: (i) relaxed cross-bridges, but not active ones, are statistically better ordered in muscle where the RLC is dephosporylated compared with phosphorylated RLC; (ii) relaxed phosphorylated and dephosphorylated cross-bridges rotate equally slowly; and (iii) active phosphorylated cross-bridges rotate considerably faster than dephosphorylated ones during isometric contraction but the duty cycle remained the same, suggesting that both phosphorylated and dephosphorylated muscles develop the same isometric tension at full Ca2+ saturation. A simple theory was developed to account for this fact. Background: Myosin cross-bridges containing phosphorylated and dephosphorylated regulatory light chain may be different. Results: Relaxed cross-bridges, but not active ones, are better ordered in muscle containing dephosphorylated RLC than phosphorylated RLC; they both rotate equally slowly. During contraction phosphorylated cross-bridges rotate faster. Conclusion: Both types of cross-bridges are functionally different. Significance: Phosphorylation of skeletal myosin RLC plays a role in regulation of skeletal muscle contraction.

Sample autofluorescence (fluorescence of inherent components of tissue and fixative-induced fluorescence) is a significant problem in direct imaging of molecular processes in biological samples. A large variety of naturally occurring fluorescent components in tissue results in broad emission that overlaps the emission of typical fluorescent dyes used for tissue labeling. In addition, autofluorescence is characterized by complex fluorescence intensity decay composed of multiple components whose lifetimes range from sub-nanoseconds to a few nanoseconds. For these reasons, the real fluorescence signal of the probe is difficult to separate from the unwanted autofluorescence. Here we present a method for reducing the autofluorescence problem by utilizing an azadioxatriangulenium (ADOTA) dye with a fluorescence lifetime of approximately 15 ns, much longer than those of most of the components of autofluorescence. A probe with such a long lifetime enables us to use time-gated intensity imaging to separate the signal of the targeting dye from the autofluorescence. We have shown experimentally that by discarding photons detected within the first 20 ns of the excitation pulse, the signal-to-background ratio is improved fivefold. This time-gating eliminates over 96 % of autofluorescence. Analysis using a variable time-gate may enable quantitative determination of the bound probe without the contributions from the background.

In this report, we describe a plasmonic platform with silver fractals for metal enhanced fluorescence (MEF) measurements. When a dye containing surface was brought into contact with silver fractals, a significantly enhanced fluorescence signal from the dye was observed. Fluorescence enhancement was studied with the N -methyl-azadioxatriangulenium chloride salt (Me-ADOTA.Cl) in PVA films made from 0.2 % PVA (w/v) solution spin-coated on a clean glass coverslip. The Plasmonic Platforms (PP) was assembled by pressing together silver fractals on one glass slide and a separate glass coverslip spin-coated with a uniform Me-ADOTA.Cl in PVA film. In addition, we also tested the ADOTA labeled human serum albumin (HSA) deposited on a glass slide for potential PP bioassay applications. Using the new PP, we could achieve more than 20-fold fluorescence enhancement (bright spots) accompanied by decrease in fluorescence lifetime. The experimental results were used to calculate the extinction (excitation) enhancement factor (GA) and fluorescence radiative rate enhancements factor (GF). No change in emission spectrum was observed for a dye with and without contact with fractals. Our studies indicate that this type of PP can be a convenient approach for constructing assays utilizing metal enhanced fluorescence (MEF) without the need for depositing the material directly on metal structures platforms.

In the present work, we have synthesized water soluble Ag nanoclusters using PMAA as a template with different Ag+: COO-ratios, to optimize it for highest brightness using less UV exposure time. Fluorescence polarization was 0.30 for and was found to vary with excitation and emission wavelength with few hundred picoseconds average fluorescence lifetime. Fluorescence Correlation Spectroscopy data depicts slower diffusion at red excitation compared to blue excitation in confocal volume than conventionally synthesized colloids proving presence of multiple sizes. The optical properties of the particles are dependent upon the excitation wavelength used and the emission wavelength collected.

Microtransponders (RFID p-Chips) derivatized with silver island film (SIF) have previously seen success as a platform for the quantification of low-abundance biomolecules in nucleic acid-based assays and immunoassays. In this study, we further characterized the morphology of the SIF as well as the polymer matrix enveloping it by scanning electron microscopy (SEM). The polymer was a two-layer silane-based matrix engulfing the p-Chip and SIF. Through a series of SEM and confocal fluorescence microscopy experiments we found the depth of the polymer matrix to be 1–2 µm. The radiative effects of the SIF/polymer layer were assessed by fluorescence lifetime imaging (FLIM) of p-Chips coated with the polymer to which a fluorophore (Alexa Fluor 555) was conjugated. FLIM images showed an 8.7-fold increase in fluorescence intensity and an increased rate of radiative decay, the latter of which is associated with improved photostability and both of which are linked to plasmonic enhancement by the SIF. Plasmonic enhancement was found to extend uniformly across the p-Chip and, interestingly, to a depth of about 1.2 µm. The substantial depth of enhancement suggests that the SIF/polymer layer constitutes a three-dimensional matrix that is accessible to solvent and small molecules such as fluorescent dyes. Finally, we confirmed that no surface-enhanced Raman scattering (SERS) is seen from the SIF/polymer combination. The analysis provides a possible mechanism by which the SIF/polymer-coated p-Chips allow a highly sensitive immunoassay and, as a result, leads to an improved bioassay platform.

The orientation of a cross-bridge is widely used as a parameter in determining the state of muscle. The conventional measurements of orientation, such as that made by wide-field fluorescence microscopy, electron paramagnetic resonance (EPR) or X-ray diffraction or scattering, report the average orientation of 1012–109 myosin cross-bridges. Under conditions where all the cross-bridges are immobile and assume the same orientation, for example in normal skeletal muscle in rigor, it is possible to determine the average orientation from such global measurements. But in actively contracting muscle, where a parameter indicating orientation fluctuates in time, the measurements of the average value provide no information about cross-bridge kinetics. To avoid problems associated with averaging information from trillions of cross-bridges, it is necessary to decrease the number of observed cross-bridges to a mesoscopic value (i.e. the value affected by fluctuations around the average). In such mesoscopic regimes, the averaging of the signal is minimal and dynamic behavior can be examined in great detail. Examples of mesoscopic analysis on skeletal and cardiac muscle are provided.

In this report we propose a lifetime-based sensing (LBS) for the detection of hyaluronidase (HA-ase). First, we heavily label hyaluronan macromolecules (HAs) with fluorescein amine. The fluorescein labeled HA (HA-Fl) has a weak fluorescence and short fluorescence lifetime due to an efficient self-quenching. Upon the addition of HA-ase, the brightness and lifetime of the sample increase. The cleavage of an HA macromolecule reduces the energy migration between fluorescein molecules and the degree of the self-quenching. A first order of the cleavage reaction depends on the amount of the HA-ase enzyme. We describe an HA-ase sensing strategy based on the lifetime changes of the fluorescein labeled HA in the presence of HA-ase. We demonstrate that the calibration of the sensing response is the same for the average lifetime as for a single exponential decay approximation, which significantly simplifies the analysis of the sensing measurements.

Silicon carbide nanowires were produced from carbon blacks at 1473 K and their microstructure was characterized by TEM, X-ray diffraction, FTIR and Raman spectroscopy. Nanowires of uniform diameters, the smallest averaging 10 nm, and narrow size distribution were obtained from graphitized carbon blacks, and their morphology depends on the properties of carbon black pecursors. High concentration of stacking faults and twins was detected. In addition to silicon carbide nanowires, a silicon carbide layer, about 20 nm thick, was formed on the surface of carbon black aggregates. The interior of the aggregates did not react and analysis of the data showed that it is composed of a mixture of amorphous carbon and small graphitic crystallites. The small lateral sizes of these crystallites remain unchanged during the graphitization process which is limited to the outer layer of the aggregates.

Posterior retinopathy of prematurity (ROP) is unusual in its atypical features and its aggressive, rapidly progressive course. It is more difficult to recognize and to treat, with many of these eyes progressing to retinal detachment despite multiple treatments with laser or cryotherapy. The authors present a case of aggressive posterior ROP refractory to multiple laser treatment. This patient was successfully treated with intravitreal bevacizumab, but required repeat treatment 4 months later. The second injection with bevacizumab was followed by progression to retinal detachment requiring surgery. The patient remains stable after surgery. [J Pediatr Ophthalmol Strabismus 2010;47:e1–e4.]

In this report, we describe a plasmonic platform with silver fractals for metal enhanced fluorescence (MEF) measurements. When a dye containing surface was brought into contact with silver fractals, a significantly enhanced fluorescence signal from the dye was observed. Fluorescence enhancement was studied with the N-methyl-azadioxatriangulenium chloride salt (Me-ADOTA·Cl) in PVA films made from 0.2% PVA (w/v) solution spin-coated on a clean glass coverslip. The Plasmonic Platforms (PP) were assembled by pressing together silver fractals on one glass slide and a separate glass coverslip spin-coated with a uniform Me-ADOTA·Cl in PVA film. In addition, we also tested ADOTA labeled human serum albumin (HSA) deposited on a glass slide for potential PP bioassay applications. Using the new PP, we could achieve more than a 20-fold fluorescence enhancement (bright spots) accompanied by a decrease in the fluorescence lifetime. The experimental results were used to calculate the extinction (excitation) enhancement factor (GA) and fluorescence radiative rate enhancements factor (GF). No change in emission spectrum was observed for a dye with or without contact with fractals. Our studies indicate that this type of PP can be a convenient approach for constructing assays utilizing metal enhanced fluorescence (MEF) without the need for depositing the material directly on metal structures platforms.

A cationic azadioxatriangulenium (ADOTA) dye was entrapped in silica thin films obtained by the sol-gel process and in poly (vinyl) alcohol (PVA) thin films. Azadioxatriangulenium is a red emitting fluorophore with a long fluorescence lifetime of ~20 ns. The fluorescent properties of azadioxatriangulenium in silica thin films and PVA films were studied by means of steady-state and time resolved fluorescence techniques. We have found that the azadioxatriangulenium entrapped in silica thin film has a wider fluorescence lifetime distribution (Lorentzian distribution), lower fluorescence efficiencies, shorter lifetimes compared to Azadioxatriangulenium in a PVA film. The local environment of azadioxatriangulenium molecules in the silica thin film is rich with water and ethanol, which creates the possibility of forming excited state aggregates due to high concentration of dye within a small confined area. In contrast to the PVA matrices, the porous silica films allow restricted rotations of Azadioxatriangulenium molecules, which result in faster and complex fluorescence anisotropy decays suggesting energy migration among dye molecules.

Familial hypertrophic cardiomyopathy (FHC) is the most common cause of sudden cardiac death in young individuals. Molecular mechanisms underlying this disorder are largely unknown; this study aims at revealing how disruptions in actin-myosin interactions can play a role in this disorder. Cross-bridge (XB) kinetics and the degree of order were examined in contracting myofibrils from the ex vivo left ventricles of transgenic (Tg) mice expressing FHC regulatory light chain (RLC) mutation K104E. Because the degree of order and the kinetics are best studied when an individual XB makes a significant contribution to the overall signal, the number of observed XBs in an ex vivo ventricle was minimized to ∼20. Autofluorescence and photobleaching were minimized by labeling the myosin lever arm with a relatively long-lived red-emitting dye containing a chromophore system encapsulated in a cyclic macromolecule. Mutated XBs were significantly better ordered during steady-state contraction and during rigor, but the mutation had no effect on the degree of order in relaxed myofibrils. The K104E mutation increased the rate of XB binding to thin filaments and the rate of execution of the power stroke. The stopped-flow experiments revealed a significantly faster observed dissociation rate in Tg-K104E vs. Tg-wild-type (WT) myosin and a smaller second-order ATP-binding rate for the K104E compared with WT myosin. Collectively, our data indicate that the mutation-induced changes in the interaction of myosin with actin during the contraction-relaxation cycle may contribute to altered contractility and the development of FHC.

Astrocytes outnumber neurons and serve many metabolic and trophic functions in the mammalian brain. Preserving astrocytes is critical for normal brain function as well as for protecting the brain against various insults. Our previous studies have indicated that methylene blue (MB) functions as an alternative electron carrier and enhances brain metabolism. In addition, MB has been shown to be protective against neurodegeneration and brain injury. In the current study, we investigated the protective role of MB in astrocytes. Cell viability assays showed that MB treatment significantly protected primary astrocytes from oxygen-glucose deprivation (OGD) & reoxygenation induced cell death. We also studied the effect of MB on cellular oxygen and glucose metabolism in primary astrocytes following OGD-reoxygenation injury. MB treatment significantly increased cellular oxygen consumption, glucose uptake and ATP production in primary astrocytes. In conclusion our study demonstrated that MB protects astrocytes against OGD-reoxygenation injury by improving astrocyte cellular respiration.

The pressure necessary to expel blood into the pulmonary circulation by the right ventricle is smaller than the pressure necessary to pump blood into the systemic circulation by the left ventricle. Nevertheless, there is little reason to believe that the left (LV) and right (RV) ventricular muscles are intrinsically different, because sarcomeric proteins of both ventricles are known to be expressed from the same genes. However, recent identification of disparities in their physiology and proteins has modified the classical outlook of their similarity and their respective cause for cardiovascular diseases. To decide whether ventricular muscles are functionally different we compared steady-state distribution of actin orientations in the left and the right ventricles at molecular levels. This distribution is a fundamental property of muscle because it reflects interaction of individual actin molecules with myosin cross-bridges. To eliminate complications arising from the differences in the basic fiber structures of the ventricles and to ensure that the molecular crowding influences contraction in the same way as it would in in-vivo conditions, we collected data from isolated myofibrils ex-vivo. To assure that each actin molecule acts independently, we labeled every 1,000 actin monomers with a fluorescent dye. The results showed that the changes in distribution of actin induced by the interaction of actin filaments with myosin heads were demonstrated only in LVs, not in RVs. This suggests that both ventricles interact differently with myosin cross-bridges. We think that the stress induced in the thin filaments of LV causes loosening of bonds between actin monomers and greater mobility of actin monomers.

Similarities exist in hormone receptors of breast, prostate, and thyroid tumors. HER2 oncogene expression is known to be present in breast and prostate tumors, but conflicting data have been published about its presence in thyroid tumors. This uncertainty prompted us to examine the incidence of HER2 overexpression in normal and malignant thyroid tissue. Normal and neoplastic thyroid tissue samples from 46 female and 9 male patients were assayed for HER2 expression by immunohistochemical assay. Of the 55 total samples, 36 were from neoplasms and 19 were from benign tissues. Significant HER2 overexpression was not found in any benign or malignant thyroid tissue. Two of 6 thyroid carcinomas from male patients showed 1+ reactivity for HER2 expression on immunohistochemistry assay, but remained negative on fluorescene in sito hybridization confirmatory testing. No significant expression of HER2 was noted in benign or malignant thyroid tissue. These results cast doubt on the value of HER2 as a prognostic factor or possible target for specific antitumor therapy for thyroid cancer.

Presenilin-1 (PS1) protein acts as passive ER Ca 2? leak channels that facilitate passive Ca 2? leak across ER membrane. Mutations in the gene encoding PS1 protein cause neurodegeneration in the brains of patients with familial Alzheimer's disease (FAD). FADPS1 mutations abrogate the function of ER Ca 2? leak channel activity in human neuroblastoma SK-N-SH cells in vitro (Das et al., J Neurochem 122(3):487-500, 2012) and in mouse embry- onic fibroblasts. Consequently, genetic deletion or muta- tions of the PS1 gene cause calcium (Ca 2? ) signaling abnormalities leading to neurodegeneration in FAD patients. By analogy with other known ion channels it has been proposed that the functional PS1 channels in ER may be multimers of several PS1 subunits. To test this hypothesis, we conjugated the human PS1 protein with an NH2-terminal YFP-tag and a COOH-terminal CFP-tag. As expected YFP-PS1, and PS1-CFP were found to be expressed on the plasma membranes by TIRF microscopy, and both these fusion proteins increased ER Ca 2? leak channel activity similar to PS1 (WT) in SK-N-SH cells, as determined by functional calcium imaging. PS1-CFP was either expressed alone or together with YFP-PS1 into SK- N-SH cell line and the interaction between YFP-PS1 and PS1-CFP was determined by Forster resonance energy transfer analysis. Our results suggest interaction between YFP-PS1 and PS1-CFP confirming the presence of a dimeric or multimeric form of PS1 in SK-N-SH cells. Lateral diffusion of PS1-CFP and YFP-PS1 in the plasma membrane of SK-N-SH cells was measured in the absence or in the presence of glycerol by fluorescence correlation spectroscopy to show that both COOH-terminal and NH2- terminal of human PS1 are located on the cytoplasmic side of the plasma membrane. Therefore, we conclude that both COOH-terminal and NH2-terminal of human PS1 may also be oriented on the cytosolic side of ER membrane.

Fluorescent nanodiamonds (NDs) are new and emerging nanomaterials that have potential to be used as fluorescence imaging agents and also as a highly versatile platform for the controlled functionalization and delivery of a wide spectrum of therapeutic agents. We will utilize two experimental methods, TIRF, a relatively simple method based on total internal reflection fluorescence and SPRF, fluorescence enhanced by resonance coupling with surface plasmons. We estimate that the SPRF method will be 100 times sensitive than currently available similar detectors based on detectors. The ultimate goal of this research is to develop microarray platforms that could be used for sensitive, fast and inexpensive gene sequencing and protein detection.

Fluorescence-based sensing and imaging experiments are constrained by the background signal generated on a sample. A main contribution to the background, besides direct scattering of excitation and Raman scattering of the solvent, comes from sample autofluorescence and additives used for sample preparation. Such unwanted signals from endogenous chromophores and fixatives typically are broad and spectrally overlap with the probe signal; thus becoming a major limitation for sensitive detection and quantitative imaging. Since the fluorescence lifetimes of the majority of naturally occurring chromophores are relatively short, long-lived fluorophores allow for background discrimination by time-gated detection. Unfortunately, the brightness of long-lived, red-emitting fluorescent probes is inherently very low, consequently limiting many applications. Recently we reported a simple new approach with bursts of closely spaced laser excitation pulses for excitation (multi-pulse excitation) that allows for many-fold increase in the intensity of a long-lived probe over the background signal. This technology can be easily implemented for biomedical diagnostics and imaging to significantly enhance the signal of long-lived probes over the background. In this report, we are discussing an example of the Ruthenium-based dye tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Ru) (Sigma–Aldrich) (~2% quantum yield and ~350 ns fluorescence lifetime) that when used with the multi-pulse approach and time-gated detection allows for high quality imaging that can easily be enhanced two orders of magnitude as compared to the normal approach (imaging with typical fluorescence microscopy).

Bovine serum albumin (BSA) protected nanoclusters (Au and Ag) represent a group of nanomaterials that holds great promise in biophysical applications due to their unique fluorescence properties and lack of toxicity. These metal nanoclusters have utility in a variety of disciplines including catalysis, biosensing, photonics, imaging and molecular electronics. However, they suffer from several disadvantages such as low fluorescence quantum efficiency (typically near 6%) and broad emission spectrum (540 nm to 800 nm). We describe an approach to enhance the apparent brightness of BSA Au clusters by linking them with a high extinction donor organic dye pacific blue (PB). In this conjugate PB acts as a donor to BSA Au clusters and enhances its brightness by resonance energy transfer (RET). We found that the emission of BSA Au clusters can be enhanced by a magnitude of two-fold by resonance energy transfer (RET) from the high extinction donor PB, and BSA Au clusters can act as an acceptor to nanosecond lifetime organic dyes. By pumping the BSA Au clusters using a high extinction donor, one can increase the effective brightness of less bright fluorophores like BSA Au clusters. Moreover, we prepared another conjugate of BSA Au clusters with the near infrared (NIR) dye Dylight 750 (Dy750), where BSA Au clusters act as a donor to Dy750. We observed that BSA Au clusters can function as a donor, showing 46% transfer efficiency to the NIR dye Dy750 with a long lifetime component in the acceptor decay through RET. Such RET-based probes can be used to prevent the problems of a broad emission spectrum associated with the BSA Au clusters. Moreover, transferring energy from BSA Au clusters to Dy750 will result in a RET probe with a narrow emission spectrum and long lifetime component which can be utilized in imaging applications.