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Despite the recognition of the lethality of cancer metastasis and the importance of developing specific anti-metastasis therapies directed at the cancer metastatic cascade, the dynamics of cancer metastasis remains poorly understood. In this study, we examined the dynamics of circulating tumor cell (CTC) survival in the bloodstream using experimental mouse models. CTCs were arrested in the capillaries by adhesion to vascular endothelium within a few minutes after injection into the bloodstream. The loss of CTCs from the circulation followed a bi-phasic decay pattern, with the number of CTCs in the bloodstream being closely associated with the number of blood circulation cycles. The calculated in vivo Vd (apparent volume of distribution) of the CTC revealed organ specific binding of the CTCs. Moreover, confocal microscopy, in vivo fluorescence imaging in syngeneic mouse metastatic models and analysis of blood circulation patterns support the notion of organ-specific tumor metastasis. The present study suggests that organ-specific tumor metastasis is influenced by cooperation between blood circulation patterns and 'seed-soil' compatibility factors. These new findings provide further insights for optimized cancer metastatic prevention strategies such as by creating a hostile circulation microenvironment and targeting the organ-specific 'seed-soil' compatibility factors.

BackgroundIntracranial photometry through chronically implanted optical fibers is a widely adopted technique for measuring signals from fluorescent probes in deep-brain structures. The recent proliferation of bright, photo-stable, and specific genetically-encoded fluorescent reporters for calcium and for other neuromodulators has greatly increased the utility and popularity of this technique.New MethodHere we describe an open-source, cost-effective, microcontroller-based solution for controlling optical components in an intracranial photometry system and processing the resulting signal.ResultsWe show proof-of-principle that this system supports high quality intracranial photometry recordings from dorsal striatum in freely moving mice. A single system supports simultaneous fluorescence measurements in two independent color channels, but multiple systems can be integrated together if additional fluorescence channels are required. This system is designed to work in combination with either commercially available or custom-built optical components. Parts can be purchased for less than one tenth the cost of commercially available alternatives and complete assembly takes less than one day for an inexperienced user.Comparison with Existing Method(s)Currently available hardware draws on a variety of commercial, custom-built, or hybrid elements for both optical and electronic components. Many of these hardware systems are either specialized and inflexible, or over-engineered and expensive.ConclusionsThis open-source system increases experimental flexibility while reducing cost relative to current commercially available components. All software and firmware are open-source and customizable, affording a degree of experimental flexibility that is not available in current commercial systems.

Over the past 50 years, protein complexes have been studied with techniques such as X-ray crystallography and electron microscopy, generating images which although detailed are static and homogeneous. More recently, limited application of in vivo fluorescence and other techniques has revealed that many complexes previously thought stable and compositionally uniform are dynamically variable, continually exchanging components with a freely circulating pool of "spares." Here, we consider the purpose and prevalence of protein exchange, first reviewing the ongoing story of exchange in the bacterial flagella motor, before surveying reports of exchange in complexes across all domains of life, together highlighting great diversity in timescales and functions. Finally, we put this in the context of high-throughput proteomic studies which hint that exchange might be the norm, rather than an exception.

Background Delayed cerebral ischemia (DCI) is a late phase of consequences of subarachnoid hemorrhage (SAH) that causes poor outcome and has become the focus of current research. The aim of this study was to characterize an experimental SAH technique for studying DCI after SAH. New method A double injection SAH rat model with a tiny incision was introduced. At 7 days post-SAH induction, the diameter and luminal cross-sectional area (CSA) of the basilar artery (BA) were measured. In vivo fluorescence microscopy and magnetic resonance perfusion-weighted imaging (MRPWI) were used to evaluate the occurrence of DCI. Normal and sham-operated groups served as References Results Compared to the sham group, in SAH group, the diameter and CSA of the BA were decreased, and the CBF in the SAH group was also reduced to barely half of the level in the sham group. Moreover, both the proportion and severity of microarterial constrictions were increased significantly in the SAH group when compared to those in the sham group. Comparison with existing methods Complete exposure of the atlanto-occipital membrane is avoided, only a tiny region is exposed to identify the puncture spot. Lower mortality, reduced operative trauma and shorter procedure time are advantages to existing models. Multiple techniques for DCI assessment were used including in vivo microscopy and MRPWI. Conclusions The current study demonstrates that our SAH model was successfully established and may serve to help identify a novel target for the treatment of DCI after SAH.

A multifunctional nanoprobe (based on Au nanostars@PDA@Fe3O4) is developed for tumor targeted imaging and targeted photothermal therapy. Au nanostars and Fe3O4 are connected with polydopamine, and combined with antibody-FITC or antibody-quantum dots for in vitro or in vivo fluorescence labeling (FL), respectively, to form the composite nanoprobe. The shape and lattice structure of Au nanostars and Fe3O4 were confirmed with TEM, HRTEM and XRD experiments. Compared with other Au nanoparticles@Fe3O4 composite probes, the Au nanostars@PDA@Fe3O4 structure has a low photothermal conversion threshold. Compared with the corresponding pure Au nanostars, the photothermal efficiency of the probe has increased by 50%, while maintaining 171% and 32% fluorescence enhancement in vitro and in vivo, respectively. Due to the charge transfer channel, the phonon emission of Au can go on in Fe3O4 via the PDA linking. Under the precise guidance of multimodal imaging, the nanoprobe conducts homogeneous photothermal ablation of bulky solid tumors (~ 400 mm3) in a xenograft mouse model. Animal model magnetic resonance imaging (MRI) results found that the MRI T2 signal intensity of the probe was 65% stronger than that of pure Fe3O4 nanoparticles. These results suggest that this nanoplatform is promising for integrated tumor diagnosis and targeted cancer therapy.

A rhodamine-based sensor ( 1 ) has been developed for the detection of chromium ions. Cr 3+ -induced opening of the rhodamine spirocycle in sensor ( 1 ) led to the distinct colorimetric and fluorescence responses. Among all the tested ions, only Cr 3+ generated a significant fluorescence enhancement of up to 13-fold, which indicated the high selectivity of 1 . Sensor ( 1 ) was successfully applied in the in vivo fluorescence imaging of Cr 3+ in C. elegans . The results provided solid evidences for the future estimation of Cr 3+ in environmental applications and tobacco samples.

Photoluminescent quantum dots (QDs) promise many biomedical applications as a new class of optical probes showing unique optical properties such as high brightness, stability, and multiplexing ability. In this review, we focus on recent research interest of medically-translatable QDs for in vitro biomedical sensing and in vivo imaging. QD-based biomedical sensing shows higher selectivity and sensitivity over conventional methods for immunohistochemistry, immunoassay, and enzymatic assays. In addition, QD-based biosensors afford simple detections of multiple biomarkers. QD probes in the second near-infrared region (1000 ≤ λ ≤ 1700 nm) show the great potential for in vivo fluorescence imaging because of the suppressed light scattering and the capability for deep tissue penetration. The second near-infrared emitting QDs covered in this review include Ag2S, Ag2Se, Ag2Te, PbS, PbSe, InAs, Cd3P2, Cd6P7, and Cd3As2 QDs. In vivo imaging properties of these QDs are highlighted with special reference to vasculature imaging and tumor localization.

The blood-brain barrier (BBB) plays important roles in both the physiological and pharmacological state of the brain. Transiently enhancing the permeability of the BBB may allow use of more types of medications for neuropsychiatric diseases. Several studies have demonstrated that seizures cause a transient decrease in BBB integrity. We studied the timing of BBB changes following seizures and the role of astrocytes in this process. Rats received 10 applications of electroconvulsive stimulation (ECS). They were then infused with sodium fluorescein, a fluorescent substance that rarely passes the BBB, via the inferior vena cava. After 120 min of circulation, the amount of sodium fluorescein in the brain was measured by two methods in vivo fluorescence imaging (total radiant efficiency) and the brain concentration of sodium fluorescein. To assess any changes to the BBB, we measured S100Β in serum, which is a standard marker of BBB breakdown that is expressed by astrocytes. We also examined ultrastructural changes following ECS. Total radiant efficiency and the brain concentration of sodium fluorescein were significantly increased in treated rats compared to controls when sodium fluorescein was injected immediately after ECS but not when the injection was performed more than 15 min after ECS. Astrocytic endfeet showed swelling around brain capillaries following ECS. In conclusion, ECS transiently enhances the permeability of the BBB, which may be accompanied by changes in astrocytic endfeet.

Topical drug delivery system to the posterior segment of the eye is facing many challenges, such as rapid drug elimination, low permeability, and low concentration at the targeted sites. To overcome these challenges, Multifunctional nanocomposite eye drops of dexamethasone-carboxymethyl-β-cyclodextrin@layered double hydroxides-glycylsarcosine (DEX-CM-β-CD@LDH-GS) were developed for relay drug delivery. Herein, our studies demonstrated that DEX-CM-β-CD@LDH-GS could penetrate through human conjunctival epithelial cells with an intact structure and exhibited integrity in the sclera of rabbits' eyes with in vivo fluorescence resonance energy transfer imaging. Consequently, tissue distribution indicated that DEX-CM-β-CD@LDH-GS nanocomposite eye drops could maintain the effective therapeutic concentration of DEX in choroid-retina within 3 h. As a relay drug delivery system, drug-CD@LDH nanocomposites offer an efficient strategy for drug delivery from ocular surface to the posterior segment.

Hemicyanine dyes including hemi-indocyanine and hemi-benzindocyanine have been attracted considerable attentions to develop near infrared probes for in vivo fluorescence imaging. However, hemi-benzothiazolecyanine dye (MTR) is rarely reported for detection analytes. In this work, to extend the sensing applications of MTR, we present an optimized route for facile preparation of the dye. And as a proof-of-concept, a self-immolative NIR probe MTR-HH based on hemi-benzothiazolecyanine dye was designed and synthesized for H2O2. The probe exhibited a 284-fold fluorescent enhancement to H2O2 with a detection limit of 0.32 μM over other biospecies. Moreover, MTR-HH was successfully applied for visualizing endogenous H2O2 in living cells and mice.

Airway inflammation is a central component of the manifestation of asthma but is relatively inaccessible to study. Current imaging techniques such as X-ray CT, MRI, and PET, have advanced noninvasive research on pulmonary diseases. However, these techniques mainly facilitate the anatomical or structural assessment of the diseased lung and/or typically use radioactive agents. In vivo fluorescence imaging is a novel method for noninvasive, real-time, and specific monitoring of lung airway inflammation, which is particularly important to gain a further understanding asthma. Compared to conventional techniques, fluorescent imaging has the advantages of rapid feedback, as well as high sensitivity and resolution. Recently, there has been an increase in the identification of biomarkers, including matrix metalloproteinases, cathepsins, selectins, folate receptor-beta, nanoparticles, as well as sialic acid-binding immunoglobulin-like lectin-F to assess the level of airway inflammation in asthma. Recent advances in our understanding of these biomarkers as molecular probes for in vivo imaging are discussed in this review.

The Red Sea is a unique marine environment but relatively unexplored. The only available long-term biological dataset at large spatial and temporal scales is remotely-sensed chlorophyll observations (an index of phytoplankton biomass) derived using satellite measurements of ocean colour. Yet such observations have rarely been compared with in situ data in the Red Sea. In this paper, satellite chlorophyll estimates in the Red Sea from the MODIS instrument onboard the Aqua satellite are compared with three recent cruises of in vivo fluorometric chlorophyll measurements taken in October 2008, March 2010 and September to October 2011. The performance of the standard NASA chlorophyll algorithm, and that of a new band-difference algorithm, is found to be comparable with other oligotrophic regions in the global ocean, supporting the use of satellite ocean colour in the Red Sea. However, given the unique environmental conditions of the study area, regional algorithms are likely to fare better and this is demonstrated through a simple adjustment to the band-difference algorithm.

A growth toxicity assay with mixed cultures of cyanobacteria and algae using in vivo fluorescence is presented. Test organisms (the green alga Pseudokirchneriella subcapitata and the cyanobacterium Aphanothece clathrata) growing alone and in a mixture were exposed to selected chemicals. P. subcapitata featured a higher sensitivity to toxicants in the presence of A. clathrata compared to the single species assay. On the other hand, growth of a cyanobacterium was not affected by the presence or absence of the green alga. The proposed method seems to be suitable for pre-screening studies of toxicants (algistatic agents, herbicides) applied into the aquatic environment and for the assessment of their impact on natural phytoplankton communities.

In vivo fluorescence imaging uses a sensitive camera to detect fluorescence emission from fluorophores in whole-body living small animals. To overcome the photon attenuation in living tissue, fluorophores with long emission at the near-infrared (NIR) region are generally preferred, including widely used small indocarbocyanine dyes. The list of NIR probes continues to grow with the recent addition of fluorescent organic, inorganic and biological nanoparticles. Recent advances in imaging strategies and reporter techniques for in vivo fluorescence imaging include novel approaches to improve the specificity and affinity of the probes and to modulate and amplify the signal at target sites for enhanced sensitivity. Further emerging developments are aiming to achieve high-resolution, multimodality and lifetime-based in vivo fluorescence imaging.

Quantitative in vivo measurements are essential for developing a predictive understanding of cellular behavior. Here we present a technique that converts observed fluorescence intensities into numbers of molecules. By transiently expressing a fluorescently tagged protein and then following its dilution during growth and division, we observe asymmetric partitioning of fluorescence between daughter cells at each division. Such partition asymmetries are set by the actual numbers of proteins present, and thus provide a means to quantify fluorescence levels. We present a Bayesian algorithm that infers from such data both the fluorescence conversion factor and an estimate of the measurement error. Our algorithm works for arbitrarily sized data sets and handles consistently any missing measurements. We verify the algorithm with extensive simulation and demonstrate its application to experimental data from Escherichia coli. Our technique should provide a quantitative internal calibration to systems biology studies of both synthetic and endogenous cellular networks.

The laser-induced fluorescence (LIF) was tested as a means to detect the effects of a pink-pigmented facultative methylotrophic bacteria (Methylobacterium) in blue agave plants, and compared with conventional techniques of leaf tissue analysis. A He–Ne laser emitting at 632.8 nm was used as the excitation source. In vivo fluorescence emission spectra were recorded in the 660–790 nm range. Fluorescence maxima were at 690 and 740 nm. The inoculated plants showed a significant change in fluorescence as compared to that of non-inoculated plants. The ratios of fluorescence intensities F690/F740 were calculated for all treatments. A comparison between conventional techniques and this non-invasive method is presented. The results of this work showed that the beneficial effects of PPFM bacteria on agave plants are detectable by LIF.

http://www.elsevier.com/locate/issn/09247963 The results of field studies of phytoplankton and dissolved organic matter DOM.in the Gulf of Riga in August-September 1993, June 1994 and April 1995 are presented. Actively excited fluorescence in UV- and visible spectral regions was used to investigate spatial distributions of DOM, Chl a, carotenoids and phycoerythrin in surface water. The fluorescent data were collected by means of laser remote sensing spectrometer LIDAR., spectrofluorometers in underway flow-through mode and in the measurements of the water samples. Pronounced variable spatial structures of phytoplankton were observed in spring 1995 and late summer 1993, while in early summer 1994 the pigment distribution was rather homogeneous. The spatial modulation of high-resolution profiles of phytoplankton with the period 3.5-5 km was detected across the gulf in all seasons probably caused by variability of hydrophysical conditions. A negative correlation of DOM concentration in surface waters and salinity was revealed in August-September 1993 and June 1994.

The fluorescence kinetics of protoporphyrin IX (PPIX) following intravesical instillation of 5-aminolaevulinic acid (5-ALA) have been studied in vivo in a rat bladder tumour model. 5-ALA dissolved in NaHCO3 was intravesically instilled for 60 min in tumour-bearing and normal bladders of Wistar rats. The fluorescence was excited with the violet lines of a Kr(+)-laser and recorded in vivo by means of a fibre coupled optical multichannel analyser. The fluorescence emission bands of PPIX at lambda = 636 nm and lambda = 708 nm were detected in normal and tumorous urothelium after only 30 min. The maximum fluorescence intensity was obtained in tumorous and normal urothelium 3-4 h after instillation. The ratio of the fluorescence intensity in tumorous to normal urothelium decreased continuously from four to about two during the time range of 6 h. PPIX fluorescence following 5-ALA instillation could also be observed in kidney and liver. Fluorescence from further porphyrin species with emission bands at lambda = 617 nm and lambda = 682 nm was detected in the bladder, indicating an efflux of hydrophilic porphyrins from the hepatic pathway.

Bone lead content of the mid-tibia was measured by in vivo fluorescence excitation in 90 females and 59 males aged between 6 and 81. The cross-sectionally derived rate of increase of tibia lead content was 0.24 +/- 0.03 microgram [g mineral]-1 yr-1. In 93 adult women, the corresponding rate of increase for calcaneus lead content was 0.12 +/- 0.11 microgram [g mineral]-1 yr-1. Comparison with European values show that, in Canada, the rates of lead accumulation are greater than those found in N. Sweden and Finland, similar to those of S. Sweden and less than values measured in England.

The use of steady state fluorescence spectroscopy in the detection and monitoring of potential photochemotherapeutic agents is examined. Problems associated with both in vitro and in vivo fluorescence measurements are investigated, and typical data are presented. Recent results on the use of fluorescence in pharmacokinetic studies are discussed, and the relative merits of in vitro vs. in vivo methods are outlined.

In vivo fluorescence is applicable to both field and laboratory measurement of chlorophyll concentration. However, in the laboratory, the ratio of chlorophyll a concentration to in vivo fluorescence changed in value during the course of bioassays. It was found, therefore, that a conversion factor for in vivo fluorescence to chlorophyll a concentration should be calculated at the beginning and end of each algal bioassay. The in vivo fluorescence values can be used without conversion for calculations of the maximum specific growth rate ( μ b , day −1 ). The ratio of chlorophyll a concentration to in vivo fluorescence was also found to be highly variable for in situ samples. The fluorescence ofdissolved substances varied widely at different sampling locations and contributed to but were not the only substances in the water responsible for the observed ratio changes. Correction of the ratio by subtraction of soluble fluorescence from total fluorescence did not result in a uniform ratio. Extracted fluorescence can be used for measuring chlorophyll when concentrations are below the detectability of in vivo fluorescence. In contrast to the variable chlorophyll a to in vivo fluorescence ratio. The relationships found between chlorophyll a and extracted fluorescence was linear; once the ratio was established for a specific fluorometer, the conversion was reasonably constant regardless of the source of the water sample.