Bobryshev, YV, Killingsworth, MC, Huynh, TG, Lord, RSA, Grabs, AJ & Valenzuela, SM 2007, 'Are calcifying matrix vesicles in atherosclerotic lesions of cellular origin?', Basic Research in Cardiology, vol. 102, no. 2, pp. 133-143.
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Over recent years, the role of matrix vesicles in the initial stages of arterial calcification has been recognised. Matrix calcifying vesicles have been isolated from atherosclerotic arteries and the biochemical composition of calcified vesicles has been studied. No Studies have yet been carried out to examine the fine structure of matrix vesicles in order to visualise the features of the consequent stages of their cacification in arteries. In the present work, a high resolution ultrastructural analysis has been employed and the study revealed that matrix vesicles in human atherosclerotic lesions are heterogeneous with two main types which we classified. Type I calcified vesicles were presented by vesicles surrounded by two electron-dense layers and these vesicles were dound to be resistant to the calcification process in atherosclerotic lesions in situ. Type II matrix vesicles were presnted by vesicles surrounded by several electron-dense layers and these vesicles were dound to represent calcifying vesicles in atherosclerotic lesions. To test the hypothesis that calcification of matrix vesicles surrounded by multilayer sheets may occur simply as a physiochemical process, independently from the cell regulation, we produced multilamellar liposomes and induced their calfcification in vitro in a manner similar to that ocurring in matrix vesicles in atherosclerotic lesions in situ.
Fu, L, Jain, A, Cranfield, C, Xie, H & Gu, M 2007, 'Three-dimensional nonlinear optical endoscopy', JOURNAL OF BIOMEDICAL OPTICS, vol. 12, no. 4.
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Jin, D, Connally, R & Piper, J 2007, 'Practical time‐gated luminescence flow cytometry. I: Concepts', Cytometry Part A, vol. 71A, no. 10, pp. 783-796.
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AbstractThe method of time‐gated detection of long‐lifetime (1–2,000 μs) luminescence‐labeled microorganisms following rapid excitation pulses has proved highly efficient in suppressing nontarget autofluorescence (<0.1 μs), scatterings, and other prompt stray light (Hemmila and Mukkala, Crit Rev Clin Lab Sci 2001;38:441–519). The application of such techniques to flow cytometry is highly attractive but there are significant challenges in implementing pulsed operation mode to rapid continuous flowing sample to achieve high cell analysis rates (Leif R, Vallarino L, Rare‐earth chelates as fluorescent markers in cell separation and analysis, In: Cell Separation Science and Technology, ACS Symposium Series 464, American Chemical Society, 1991, pp 41–58; Condrau et al., Cytometry 1994;16:187–194; Condrau et al., Cytometry 1994;16:195–205; Shapiro HM, Improving signals from labels: Amplification and other techniques, In: Practical Flow Cytometry, 4th ed., Wiley, New York, 2002, p 345). We present here practical approaches for achieving high cell analysis rates at 100% detection efficiency, using time‐gated luminescence (TGL) flow cytometry. In particular, we report that new‐generation UV LEDs are practical sources in TGL flow cytometry.Spatial effects of long‐lived luminescence from the target fluorophore in a fast‐flowing sample stream have been investigated; excitation and detection requirements in TGL flow cytometry were theoretically analyzed; two practical approaches, a triggered model and a continuous flow‐section model, were considered as a function of flow speed, sizes and relative positions of the excitation/detection spots, label lifetime, excitation pulse duration/intensity, and detection duration. A particular configuration using LED excitation to detect europium dye‐labeled targets in such a system has been modeled in detail.In the triggered model, TGL mode is confined to a low ...
Jin, D, Connally, R & Piper, J 2007, 'Practical time‐gated luminescence flow cytometry. II: Experimental evaluation using UV LED excitation', Cytometry Part A, vol. 71A, no. 10, pp. 797-808.
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AbstractIn the previous article [Part 1 (8)], we have modelled alternative approaches to design of practical time‐gated luminescence (TGL) flow cytometry and examined the feasibility of employing a UV LED as the excitation source for the gated detection of europium dye labelled target in rapid flow stream. The continuous flow‐section approach is well suited for rare‐event cell counting in applications with a large number of nontarget autofluorescent particles. This article presents details of construction, operation and evaluation of a TGL flow cytometer using a UV LED excitation and a gated high‐gain channel photomultiplier tube (CPMT) for detection. The compact prototype TGL flow cytometer was constructed and optimised to operate at a TGL cycle rate of 6 kHz, with each cycle consisting of 100 μs LED pulsed excitation and ∼60 μs delay‐gated detection. The performance of the TGL flow cytometer was evaluated by enumerating 5.7 μm Eu3+ luminescence beads (having comparable intensity to europium‐chelate‐labeled Giardia cysts) in both autofluorescence‐rich environmental water concentrates and Sulforhodamine 101 (S101) solutions (broadband red fluorescence covering the spectral band of target signals), respectively.The prototype TGL flow cytometer was able to distinguish the target beads, and a maximum signal to background ratio of 38:1 was observed. Neither the environmental water concentrates nor S101 solution contributed to the background in the TGL detection phase. The counting efficiency of the TGL flow cytometer was typically >93% of values determined using conventional counting methods. © 2007 International Society for Analytical Cytology
Krishnamurthy, V, Luk, KY, Cornell, B, Prashar, J, di Maio, IL, Islam, H, Battle, AR, Valenzuela, SM & Martin, DK 2007, 'Gramicidin Ion Channel-Based Biosensors: Construction, Stochastic Dynamical Models, and Statistical Detection Algorithms', IEEE Sensors Journal, vol. 7, no. 9, pp. 1281-1288.
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This paper deals with the experimental construction, stochastic modeling, and statistical signal processing of a novel, artificially constructed biosensor comprised of biological ion channels. Such nanoscale biosensors have been built by incorporating dimeric gramicidin A (bis-gA) ion channels into bilayer membranes of giant unilamellar liposomes, and then excising small patches of the membrane loaded with ion channels. We present a stochastic model for the response of the biosensor and present statistical model validation tests to verify the adequacy of the model., We show that in the presence of specific target molecules, the statistics of the gating mechanisms of the gA channels are altered. By capturing the change in real time, we devise a maximum-likelihood detector to detect the presence of target molecules. To test the sensitivity of this model, we conducted patch-clamp experiments with two compounds known to inhibit conduction of the gA channels. We found experimentally that the real-time detection algorithm was able to accurately identify the addition of the compounds even when the alterations in the patch-clamp recordings were very small. This algorithm provides the sensitive detection system for ongoing development of lipid-based nanosensors.
Lou, W, Jin, D, Wang, D, Xu, X, Kuang, T & Qin, X 2007, 'An analysis of clinico-pathologic features of intraductal papillary mucinous neoplasm of the pancreas', Frontiers of Medicine in China, vol. 1, no. 2, pp. 173-176.
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Pissuwan, D, Cortie, CH, Valenzuela, SM & Cortie, MB 2007, 'Gold nanosphere-antibody conjugates for hyperthermal therapeutic applications', GOLD BULLETIN, vol. 40, no. 2, pp. 121-129.
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Gold nanoparticles can be conjugated with antibodies or other proteins, and the resulting composite particles will selectively attach to various kinds of biological material. Although exploitation of this for staining microscopy specimens is well known, there has recently been interest in attaching gold nanoparticles to live cells for therapeutic reasons. One motication is that gold nanoparticles display a strong plasmon resonance with light, which can be exploted in principle for an 'in vivo' photothermal therapy. The treatment of cancer by this technique has recently received attention by others, but here we show how gold nanoparticle based therapies can be developed to target live macrophage cells. We have employed 'active targeting' a scheme in which gold nanoparticles are functionalised with an antibody specific to the target macrophage cell. We describe how to prepare the conjugated particles, demonstrate that they will selectively attach 'in vitro' to their target macrophage cell but not to a non-target cell type and show that their presence renders the target cell susceptible to destruction by a low power laser.
Pissuwan, D, Valenzuela, SM, Killingsworth, MC, Xu, X & Cortie, MB 2007, 'Targeted destruction of murine macrophage cells with bioconjugated gold nanorods', JOURNAL OF NANOPARTICLE RESEARCH, vol. 9, no. 6, pp. 1109-1124.
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Gold nanorods manifest a readily tunable longitudinal plasmon resonance with light and consequently have potential for use in photothermal therapeutics. Recent work by others has shown how gold nanoshells and rods can be used to target cancer cells, which can then be destroyed using relatively high power laser radiation (similar to 1x10(5) to 1x10(10) W/m(2)). Here we extend this concept to demonstrate how gold nanorods can be modified to bind to target macrophage cells, and show that high intensity laser radiation is not necessary, with even 5x10(2) W/m(2) being sufficient, provided that a total fluence of similar to 30 J/cm(2) is delivered. We used the murine cell line RAW 264.7 and the monoclonal antibody CD11b, raised against murine macrophages, as our model system and a 5 mW solid state diode laser as our energy source. Exposure of the cells labeled with gold nanorods to a laser fluence of 30 J/cm(2) resulted in 81% cell death compared to only 0.9% in the control, non-labeled cells.
Pissuwan, D, Valenzuela, SM, Miller, CM & Cortie, MB 2007, 'A golden bullet? Selective targeting of toxoplasma gondii tachyzoites using anti body-functionalized gold nanorods', NANO LETTERS, vol. 7, no. 12, pp. 3808-3812.
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Conjugates of gold nanoparticles and antibodies have useful functionalities. Here we show how they can be used to selectively target and destroy parasitic protozoans. Gold nanorods were conjugated with an anti-Toxoplasma gondii antibody and used to target the extracellular tachyzoite which is an infectious from on an obligate parasite Toxoplasma gondii. Subsequent laser irradiation was used to kill the targeted protozoans. This concept provides a new paradigm for the treatment of parasitic protozoans.
Pissuwan, D, Valenzuela, SM, Miller, CM & Cortie, MB 2007, 'A golden bullet? Selective targeting of Toxoplasma gondii tachyzoites using antibody-functionalized gold nanorods.', Nano Lett, vol. 7, no. 12, pp. 3808-3812.
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Conjugates of gold nanoparticles and antibodies have useful functionalities. Here, we show how they can be used to selectively target and destroy parasitic protozoans. Gold nanorods were conjugated with an anti-Toxoplasma gondii antibody and used to target the extracellular tachyzoite which is an infectious form of an obligate parasite Toxoplasma gondii. Subsequent laser irradiation was used to kill the targeted protozoans. This concept provides a new paradigm for the treatment of parasitic protozoans.
