Measuring the Optical Properties of Human Muscle Tissue using Time-of-Flight Spectroscopy in the Near Infrared

Optical spectroscopy is commonly used in technology and science today. The presence and concentration of a substance can be determined by its spectral signature, the typical wavelengths that are absorbed (or emitted) by the atoms or molecules. Standard absorption spectroscopy requires that the substance is clear and that the optical path-length is known to obtain quantitative information. Unfortunately in many materials, such as human tissue or pharmaceutical tablets, there are also a strong scattering of light which complicates measurements. The pathlength of the light is now no longer known and the intensity of the detected light can in many cases be more affected by high scattering than by the absorption values. One method to separate these two values are photon Time-of-Flight Spectroscopy (TOFS). By sending many short light pulses through a sample, and recording the time for a single photon to arrive at our detector for each pulse, we can build a histogram that represents the broadening of the light pulse that is determined by both the scattering and absorption. By tting computer generated theoretical curves against the recorded histogram, we can extract the values for absorption and scattering from the curve with the best fit. The Biophotonics group at the department of Physics at Lund University has implemented a system that can deliver continuous absorption/ scattering spectra from 500 nm to 1400 nm. It uses a broadband laser as source and tunable optical filters to select narrow wavelength bands for measurements. In this thesis we expanded the set-up with a new laser source and new filters. We performed tests comparing measurements using the new filter with results from the old system. We could show that the new lter gave better results, due to the sharper line width of the output light pulse. Study were also conducted on the absorption and scattering spectra of muscle tissue in the near infrared, between 650 nm and 1350 nm, probing the lower left arm of a volunteer. This was performed by positioning two optical fibres against the skin, sending light in with one and measuring the scattered light arriving at the second. The results are shown to be comparable to other studies done for wavelengths up to 1000 nm, and give new data up to 1350 nm that is consistent with the properties of the main absorbing components in this range, lipids and water. One uncertainty that appear in the results are due to the compression of the tissue by the fibres, this is something that should be addressed in repeat measurement that where not possible to perform in this study.Att använda hur ljus absorberas för att ta reda på något om ett ämne är inget konstigt, vi har alla gjort det. När vi blandar ett glas saft tittar vi på färgen och kan säga av erfarenhet hur stark den är. Precis på samma sätt fungerar absorptionsspektroskopi, genom att titta på hur mycket ljus som passerar genom ett material kan vi bestämma koncentrationen av ett ämne vi är intresserade av, om vi mäter hur mycket ljus detta ämne absorberar och vet hur lång väg genom materialet som ljusstrålen går. Olika färger på ljuset, olika våglängder, absorberas olika mycket av ämnen, och detta kan användas för att bestämma vad som finns i det vi tittar på. På så sätt kan vi enkelt skilja på gul apelsinsaft och röd jordgubbssaft. För saft är detta enkelt, men det blir mycket svårare för till exempel mjölk. Anledningen till att mjölk är vit är nämligen att allt ljus som kommer in i mjölken sprids, det studsar runt mellan små fettdroppar och luftbubblor. Detta gör att det är omöjligt att veta hur lång sträcka ljuset gått igenom mjölken, för vi vet inte hur många gånger det ändrat riktning på vägen. Nu beror mängden ljus som passerar materialet på både spridningen och absorptionen, och vi måste ta hänsyn till bägge värden. Det går inte enkelt att skilja på olika mjölktyper bara genom att titta på dem. Ett sätt att mäta både absorption och spridning som används i denna avhandling kallas photon Time-of-Flight Spectroscopy, pTOFS, där man mäter den tid det tar för enstaka ljuspartiklar, fotoner, att passera igenom materialet. Genom att göra många mätningar kan man bygga upp en graf som representerar den statistiska fördelningen av tiden det tar för fotonerna att passera, och formen på denna graf innehåller information om hur mycket absorption och spridning som ljuset utsatts för på sin väg. Genom att göra datorberäkningar där vi varierar spridning och absorption kan vi ta fram teoretiska grafer med kända värden. Sedan jämför vi datorgraferna med de uppmätta, och när vi hittar en som ser exakt likadan ut så kan vi läsa av värdena för absorption och spridning. En typ av kraftigt spridande material är biologisk vävnad. Det finns redan många metoder att få fram information om vävnad, t.ex. röntgen, magnetkamera eller vävnadsprov. Fördelen med att använda ljus framför andra metoder är att det inte orsakar någon skada på vävnaden och det är relativt snabbt och billigt. Den stora nackdelen är att ljuset inte förmår tränga in så långt i vävnaden, typiskt nån millimeter till några centimeter beroende på vävnadstyp och ljusets våglängd. Denna avhandling har som mål att mäta värden för absorption och spridning i mänsklig muskelvävnad för infrarött ljus. Detta har utförts med en pTOFS-uppställning på avdelningen för atomfysik vid Lunds Universitet. Först installeras nya delar för att få bättre ljusstyrka och vi utvärderar dessa, för att sedan mäta upp absorption och spridningsvärden för en muskel på en frivillig persons underarm. Resultaten visar att det är möjligt att använda metoden en bit in i det infraröda området, men sedan ökar absorptionen från vatten i vävnaden kraftigt och omöjliggör vidare mätning

Use of an Immobilized Monoclonal Antibody to Examine Integrin α5β1 Signaling Independent of Cell Spreading

Cell attachment to the extracellular matrix (ECM) engages integrin signaling into the cell, but part of the signaling response also stem from cell spreading (3). To analyze specific integrin signaling-mediated responses independent of cell spreading, we developed a method engaging integrin signaling by use of an immobilized anti-integrin monoclonal antibody (mab) directed against the fibronectin (FN) receptor integrin α5β1. ECV 304 cells were plated onto FN or immobilized mab JBS5 (anti-integrin α5β1) or onto poly-L-lysin (P-L-L), which mediates integrin-independent attachment. Cells attached and spread on FN, while cells on JBS5 or P-L-L attached but did not spread. Importantly, plating onto FN or mab JBS5 gave rise to identical integrin-induced responses, including a down-regulation of the cyclin-dependent kinase (Cdk2) inhibitors p21(CIP1) and p27(KIP1), while attachment to P-L-L did not. We conclude that engagement of the FN-receptor integrin α5β1 induces integrin signaling regulating the Cdk2-inhibitors independent of cell spreading and present a method for how integrin signaling can be analyzed separate from the effects of cell spreading

Integrin-mediated Cell Attachment Induces a PAK4-dependent Feedback Loop Regulating Cell Adhesion through Modified Integrin αvβ5 Clustering and Turnover

This article presents a novel mechanism deployed by cells to tune cell adhesion levels through the autoinhibitory regulation of integrin adhesion involving the activation of PAK4

Single fluorescent protein-based Ca2+ sensors with increased dynamic range

<p>Abstract</p> <p>Background</p> <p>Genetically encoded sensors developed on the basis of green fluorescent protein (GFP)-like proteins are becoming more and more popular instruments for monitoring cellular analytes and enzyme activities in living cells and transgenic organisms. In particular, a number of Ca²⁺sensors have been developed, either based on FRET (Fluorescence Resonance Energy Transfer) changes between two GFP-mutants or on the change in fluorescence intensity of a single circularly permuted fluorescent protein (cpFP).</p> <p>Results</p> <p>Here we report significant progress on the development of the latter type of Ca²⁺sensors. Derived from the knowledge of previously reported cpFP-based sensors, we generated a set of cpFP-based indicators with different spectral properties and fluorescent responses to changes in Ca²⁺concentration. Two variants, named Case12 and Case16, were characterized by particular high brightness and superior dynamic range, up to 12-fold and 16.5-fold increase in green fluorescence between Ca²⁺-free and Ca²⁺-saturated forms. We demonstrated the high potential of these sensors on various examples, including monitoring of Ca²⁺response to a prolonged glutamate treatment in cortical neurons.</p> <p>Conclusion</p> <p>We believe that expanded dynamic range, high brightness and relatively high pH-stability should make Case12 and Case16 popular research tools both in scientific studies and high throughput screening assays.</p

Community standards for open cell migration data

Cell migration research has become a high-content field. However, the quantitative information encapsulated in these complex and high-dimensional datasets is not fully exploited owing to the diversity of experimental protocols and non-standardized output formats. In addition, typically the datasets are not open for reuse. Making the data open and Findable, Accessible, Interoperable, and Reusable (FAIR) will enable meta-analysis, data integration, and data mining. Standardized data formats and controlled vocabularies are essential for building a suitable infrastructure for that purpose but are not available in the cell migration domain. We here present standardization efforts by the Cell Migration Standardisation Organisation (CMSO), an open community-driven organization to facilitate the development of standards for cell migration data. This work will foster the development of improved algorithms and tools and enable secondary analysis of public datasets, ultimately unlocking new knowledge of the complex biological process of cell migration

WRAP53 Is Essential for Cajal Body Formation and for Targeting the Survival of Motor Neuron Complex to Cajal Bodies

The WRAP53 protein regulates the formation and maintenance of Cajal bodies (nuclear sub-organelles), as well as directs the recruitment of nuclear factors to Cajal bodies

Processing unit resources in a distributed computing systems

The described program is designed for collecting, storing and processing data of distributed file system

New control of the senescence barrier in breast cancer

Normal cells exposed to cancer-causing events respond by triggering cellular senescence, a stress response which halts cell proliferation and constitutes a protective anti-cancer barrier. We have uncovered a previously unknown signaling pathway implicating p21-activated kinase 4 (PAK4) in the control of senescence in breast cancer, via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) subunit RELB and the CCAAT-enhancer-binding protein beta (C/EBPβ)