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In a paper published at the J Invest Dermatol in 1998 Nik Kollias and coworkers described distinct changes in skin native fluorescence associated with skin aging and photoaging, using in vivo fluorescence excitation spectroscopy. The assignment of the 295 nm band to tryptophan fluorescence had a profound significance influencing many later studies from multiple groups. The reproducible changes in skin native fluorescence suggested that aging causes predictable alterations in both the epidermis and the dermis, whereas chronic UV exposure induces the appearance of new fluorophores. This seminal, but insufficiently widely appreciated work deserves re-examination as it points to important horizons in future experimental dermatology, such as cancer diagnostics, diabetes, wound healing, and understanding skin aging and photoaging mechanisms.

Osteophytes are a typical radiographic finding during osteoarthritis (OA), but the mechanisms leading to their formation are not well known. Comparatively, fracture calluses have been studied extensively; therefore, drawing comparisons between osteophytes and fracture calluses may lead to a deeper understanding of osteophyte formation. In this study, we compared the time courses of osteophyte and fracture callus formation, and investigated mechanisms contributing to development of these structure. Additionally, we investigated the effect of mechanical unloading on the formation of both fracture calluses and osteophytes. Mice underwent either transverse femoral fracture or non-invasive anterior cruciate ligament rupture. Fracture callus and osteophyte size and ossification were evaluated after 3, 5, 7, 14, 21, or 28 days. Additional mice were subjected to hindlimb unloading after injury for 3, 7, or 14 days. Protease activity and gene expression profiles after injury were evaluated after 3 or 7 days of normal ambulation or hindlimb unloading using in vivo fluorescence reflectance imaging (FRI) and quantitative PCR. We found that fracture callus and osteophyte growth achieved similar developmental milestones, but fracture calluses formed and ossified at earlier time points. Hindlimb unloading ultimately led to a threefold decrease in chondro/osteophyte area, and a twofold decrease in fracture callus area. Unloading was also associated with decreased inflammation and protease activity in injured limbs detected with FRI, particularly following ACL rupture. qPCR analysis revealed disparate cellular responses in fractured femurs and injured joints, suggesting that fracture calluses and osteophytes may form via different inflammatory, anabolic, and catabolic pathways. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:699-710, 2018.

Noninvasive in vivo fluorescence imaging of small animals as a method in preclinical research has developed considerably in recent years, and is used widely across a variety of disciplines such as oncology and infectious disease research. It provides a means of detecting a fluorescent signal within a living animal reflecting specific, mostly disease-related, processes, such as parts of the host immune response, inflammation, cancer growth or presence of pathogens. As well as offering many advantages as a standalone technique, it can also be highly complementary to other imaging modalities. This review discusses aspects of light distribution in animal tissue and the implications on in vivo imaging; the most widely used imaging techniques including planar and tomographic imaging; advantages and challenges of the techniques; fluorescent contrast agents and some examples of applications. Rather than in detail reviewing studies using in vivo fluorescence imaging, we focus on the principles and practicalities of the method itself, so that the reader can apply these to their own research question.

Multimodal: Gold nanorods are coated with silica/polymer mutilayers, doped with surface-enhance Raman scattering (SERS) and fluorescence agents as well as photosensitizers. The structural and optical properties are tunable and stable in solutions and in living bodies. A real-time and specific in vivo SERS and fluorescence detection method using this structure is applied for tumor detection and subsequent photodynamic therapy (PDT).

The applications of in vivo probes that can detect the fluorescence of cyanobacterial phycocyanin are emerging and widely used for cyanobacterial detection in source waters. The objectives of this project were to study the sources of interferences involved with the readings of five probes (three commercially available probes and two prototype probes) using laboratory cultures and field samples. To compare the direct readings of different probes, the probe readings were presented in the form of a biovolume equivalent of cyanobacteria. Inorganic turbidity and the presence of algal biomass interfered with probe readings. A correction factor was developed for the cyanobacteria probes using simultaneous chlorophyll a measurements. The field data demonstrate that the potential underestimation of cyanobacterial biomass that corresponds to alert levels is a major issue with the application of in vivo probes. These alert levels are used to trigger monitoring and management actions. This study shows that the correlation between a probe’s reading and cell count is almost meaningless, and that the correlation to biovolume is a relevant option for management purposes. Results show that probe users should be fully aware of the sources of interferences when applying and interpreting the results. In addition, the authors offer a novel procedure that corrects for chlorophyll a interference.

The synthesis of new Lucifer Yellow labeled hyaluronic acid- and alginate hydrogels that are covalently cross-linked is reported. Biocompatibility and biodegradation of the fluorescent tagged hydrogel is investigated using an in vivo fluorescence imaging system.

Non-technical summary Wound closure depends on vascular ingrowth into the injured area and this process has traditionally been studied in tissue sections of animals ex vivo. Following the creation of a wound within a surgically implanted dorsal window chamber, we captured micro- scopicimagesoftheingrowingvasculatureonsuccessivedaysafterinjury.Usingacombinationof surgical,confocalmicroscopicandmathematicaltechniqueswequantifiedthefluxofplasmainto and around vessels including: newly formed vessel sprouts, nascent flowing vascular segments and pre-existing vessels within the same wound. From these analyses we are able to discriminate: (1) vessels with differing maturity, (2) that vascular sprouts get progressively less leaky and (3) TNP-470 (an anti-angiogenic agent), reduces leakiness in sprouts with co-incident secondary effects on pre-existing vessels. These techniques can be used to assess both functional maturity and the effects of therapeutics on the vasculature of healing wounds. Abstract Regeneration of injured tissue is a dynamic process, critically dependent on the formation of new blood vessels and restructuring of the nascent plexus. Endothelial barrier function, a functional correlate of vascular restructuring and maturation, was quantified via intravital microscopic analysis of 150 kDa FITC-dextran-perfused blood vessels within discrete wounds created in the panniculus carnosus (PC) muscle of dorsal skinfold chamber (DSC) preparationsinmice.Timetorecoveryofhalf-peakfluorescenceintensity(t1/2)withinindividual vessel segments in three functional regions of the wound (pre-existing vessels, angiogenic plexus and blind-ended vessels (BEVs)) was quantified using in vivo fluorescence recovery after photo- bleaching (FRAP) and linear regression analysis of recovery profiles. Plasma flux across the walls of new vessel segments, particularlyBEVs, was greater than that of pre-existing vessels at days5-7 after injury (P

In vivo fluorescence imaging with near-infrared (NIR) light holds enormous potential for a wide variety of molecular diagnostic and therapeutic applications. Because of its quantitative sensitivity, inherent biological safety, and relative ease of use (i.e., with respect to cost, time, mobility, and its familiarity to a diverse population of investigators), fluorescence-based imaging techniques are being increasingly utilized in small-animal research. Moreover, there is substantial interest in the translation of novel optical techniques into the clinic, where they will prospectively aid in noninvasive and quantitative screening, disease diagnosis, and post-treatment monitoring of patients. Effective deep-tissue fluorescence imaging requires the application of exogenous NIR-emissive contrast agents. Currently, available probes fall into two major categories: organic and inorganic NIR fluorophores (NIRFs). In the studies reviewed herein, we utilized polymersomes (50 nm to 50 microm diameter polymer vesicles) for the incorporation and delivery of large numbers of highly emissive oligo (porphyrin)-based, organic NIRFs.

Taking continuous spatiotemporal in situ measurements with multi-probes in fast-flowing waters/rivers can be problematic because the sensors may be damaged by high shear forces and flotsam. To protect the multi-probe and to enable easy access for the maintenance and calibration of the sensors, a special multi-probe holder fixed in a hydrographic slot was developed. The validation of the probe system revealed a “memory effect” at short time scales (< 10 s) within sharp gradients caused by the overflow container of the multi-probe rack keeping the sensors submerged in the sample water. Continuously recorded data (conductivity, temperature, pH, oxygen concentration and saturation, as well as in vivo fluorescence of chlorophyll-a) from a research cruise on board the RV ALBIS along the river Elbe (river km 309) and entering the river Saale are presented. This river stretch upstream of the city of Magdeburg to the mouth of the Saale tributary was found to have a complex physicochemical character, which is attributable to the long mixing process of water from the river Saale and the river Elbe. Kontinuierliche Multisondenmessungen in schnell stromendem Wasser mittels eines hydrographischen Schachts Kontinuierliche raumliche und zeitliche In-situ-Messungen mit Multisonden in schnell stromenden Gewassern/Flussen konnen problematisch sein, da hohe Scherkrafte und Treibgut die Sensoren beschadigen konnten. Um diese zerstorenden Effekte auf die Multisonde zu vermeiden und einen einfachen Zugang fur die Kalibrierung und Wartung der Sensoren zu erhalten, wurde eine spezielle Multisonden-Halterung, die in einem hydrographischen Schacht fixiert wird, entwickelt. Die Validierung des Sondensystems ergab fur kurze Zeitskalen (< 10 s) innerhalb starker Gradienten einen „Memory-Effekt”, der durch den Uberlaufbehalter des Multisondengestells, der die Sensoren im Probenwasser halt, hervorgerufen wird. Es werden kontinuierlich aufgenommene Daten (Leitfahigkeit, Temperatur, pH-Wert, Sauerstoffkonzentration und -sattigung sowie In-vivo-Fluoreszenz des Chlorophyll-a) von einer Untersuchungsfahrt mit dem Forschungsschiff FS „ALBIS” entlang der Elbe (Flusskilometer 309) bis in die Saale vorgestellt. Fur den Flussabschnitt oberhalb der Stadt Magdeburg bis zur Mundung des Nebenflusses Saale konnte eine komplexe physikochemische Situation nachgewiesen werden, die durch einen langen Vermischungsprozess von Elbe- und Saalewasser verursacht wird.

Keywords: Photomedicine group Reference LPAS-ARTICLE-1998-003View record in Web of Science Record created on 2007-07-20, modified on 2016-08-08

Endoscopic probes have been incorporated into a fluorescent imaging system for the remote quantitation of tissue selective markers. Resolution at the level of 114 line pairs/mm allows visualization of regions that are approximately 6 mm wide. Tissue selective markers, based on polyazamacrocyclic chelates of terbium increase contrast and can be quantified in tissues at the sub-picomole level. Minimally invasive in vivo fluorescence imaging is demonstrated. The potential for application of the system to disease diagnosis and bone graft morphology quantitation is discussed.

Background/aims: The methods available for testing the efficacy of topical sunscreens have improved considerably in recent years. Nevertheless, so far no simple and rapid test has been proposed to measure in vivo transmission spectra of sunscreens in the UVA region. Methods: Spectral changes that occur after sunscreen application were measured with a fluorescence spectrometer (LS 50B, Perkin Elmer, UK) equipped with a Y-shape quartz guide for in vivo measurements. Three sunscreens with different protection factors in the UVA range were tested. The excitation-emission maps of human collagen, skin and sunscreens were analysed. Results: As a consequence of the human skin and sunscreen fluorescence map analysis, the optimal spectral regions (both for direct and indirect fluorescence measurements) were detected. In vivo fluorescence and remittance spectroscopy were used to investigate the time dependence in transmission spectra of epidermis with applied sunscreens. We also evaluated the feasibility of in vivo fluorescence measurements for the investigation of the sunscreens’water-resistance. Conclusion: The procedure is simple, and values obtained can be used to predict UVA protection on the basis of the mathematical algorithms.

SUMMARY. The variation in the ratio (R) between cellular fluorescence of chlorophyll-a and unit extractable chlorophyll-a was examined with natural populations of phytoplankton and unialgal cultures. Photo-inhibition of in vivo fluorescence was observed al high values of irradiance with natural populations and in algal cultures, except with blue-green algae. If samples were dark-adapted (< 6 W m−2) before measurements were made, changes of fluorescence due to photo-inhibition could be minimized. Measurements of in vivo fluorescence with dark-adapted samples of phytoplankton, dominated by species showing large values of R, gave significant correlations (P< 0.001) with determinations of chlorophyll-a concentration over periods of several weeks. The values for R for blue-green algae were appreciably lower than for other algal groups. This, and their lack of photo-inhibition effects at high irradiance values, are attributed to the association of most of chlorophyll-a with photosystem I which fluoresces weakly compared to chlorophyll-a in photosystem II. The significance of these findings for ecological studies is discussed.

Cultures of freshwater algae, representing three algal divisions, Synura petersenii Korshikov; Chlamydomonas sp.: and Nitzschia sp., were subjected to four different mercury-temperature shock interactions to demonstrate synergistic effects between mercury and temperature. Algal growth, measured by temporal changes in vivo fluorescence of chlorophyll was used to ascertain the effects. Mercury addition and temperature shock had various inhibitory effects on algal growth. Prior environmental conditions influence the effect of subsequent treatments. Growth of S. petersenii was severely inhibited by mercury in all experiments. Control cultures would not grow at 30 C and died when shacked at this temperature. Chlamydomonas sp. cultures initially inhibited by mercury were able to recover under most conditions after a period of reduced growth. Nitzschia sp. was resistant to mercury except when simultaneously shocked with temperature. Mercury analyses showed that Nitzschia cells at 25 C and 30 C contained a high percentage of the mercury initially added to the cultures. There was a significant loss of mercury at the end of each experiment from all cultures, probably due to volatilization.