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Wang J, Zhu X, Mollaee M, Zong J, Peyhambarian N. Efficient energy transfer from Er 3+ to Ho 3+ and Dy 3+ in ZBLAN glass. OPTICS EXPRESS 2020; 28:5189-5199. [PMID: 32121744 DOI: 10.1364/oe.384435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/29/2020] [Indexed: 06/10/2023]
Abstract
Spectroscopic properties of erbium (Er3+)-, holmium (Ho3+)-, dysprosium (Dy3+)-doped and Er3+/Ho3+, Er3+/Dy3+ co-doped ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glasses were studied. The experimental results show that efficient energy transfer from Er3+ to Ho3+ and Dy3+ occurs in the Er3+/Ho3+ and Er3+/Dy3+ co-doped ZBLAN glasses, respectively. This valuable discovery enables us to design and develop high power Ho3+-doped and Dy3+-doped ZBLAN fiber lasers in the 3 µm wavelength region that can be pumped with readily available high-efficiency, high-power diode laser pumps at 980 nm.
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Wei C, Shi H, Luo H, Zhang H, Lyu Y, Liu Y. 34 nm-wavelength-tunable picosecond Ho 3+/Pr 3+-codoped ZBLAN fiber laser. OPTICS EXPRESS 2017; 25:19170-19178. [PMID: 29041110 DOI: 10.1364/oe.25.019170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 07/24/2017] [Indexed: 06/07/2023]
Abstract
We propose and demonstrate a broadly wavelength-tunable mode-locked Ho3+/Pr3+-codoped ZBLAN fiber laser operating in the 3 μm mid-infrared spectral region based on a semiconductor saturable absorber mirror. Wavelength selection is realized by rotating a plane ruled grating. The fiber laser exhibits stable continuous-wave mode-locking operation over a wide wavelength tuning range of 34 nm (2842.2 nm~2876.2 nm), with a 10.17 MHz repetition rate and 22 ps pulse duration. Stable mode-locked pulses can be maintained until the launched pump power of 1.25 W. Maximum average output power of 127.7 mW and the corresponding pulse energy of 12.56 nJ are achieved. To the best of our knowledge, this is the first demonstration of a wavelength-tunable mode-locked fiber laser operating in the 3 μm spectral region. Such simple, robust, and versatile mid-infrared picosecond laser source can find various applications in laser surgery, spectroscopy, and nonlinear frequency conversion.
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You Z, Sun Y, Sun D, Zhu Z, Wang Y, Li J, Tu C, Xu J. High performance of a passively Q-switched mid-infrared laser with Bi 2Te 3/graphene composite SA. OPTICS LETTERS 2017; 42:871-874. [PMID: 28198886 DOI: 10.1364/ol.42.000871] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report passively Q-switched ∼2 and ∼3 μm mid-infrared (MIR) solid-state lasers with a self-assembly solvothermal-synthesized Bi2Te3/graphene heterostructure saturable absorber (SA) for the first time. Based on the oxidation resistance and high thermal conductivity of graphene, and large modulation depth of Bi2Te3 nanosheets, two high-performance Q-switching lasers were realized. One is a Tm:YAP laser with a maximum average output power of 2.34 W and a pulse width of 238 ns at ∼2 μm. The corresponding maximum pulse peak power was 91 W, which was much improved in comparison with the pure graphene-based Tm laser. The other one is an Er:YSGG laser producing a pulse width of 243 ns, which is the shortest among the 2D SAs-based ∼3 μm solid-state lasers, as far as we know. Our results indicate that such a composite Bi2Te3/graphene material is a promising SA for generating high-performance mid-infrared pulse lasers.
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Iwanski J, Wong RK, Larson DF, Ferng AS, Runyan RB, Goldstein S, Khalpey Z. Remodeling an infarcted heart: novel hybrid treatment with transmyocardial revascularization and stem cell therapy. SPRINGERPLUS 2016; 5:738. [PMID: 27376006 PMCID: PMC4909685 DOI: 10.1186/s40064-016-2355-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 05/17/2016] [Indexed: 01/04/2023]
Abstract
Transmyocardial revascularization (TMR) has emerged as an additional therapeutic option for patients suffering from diffuse coronary artery disease (CAD), providing immediate angina relief. Recent studies indicate that the volume of surgical cases being performed with TMR have been steadily rising, utilizing TMR as an adjunctive therapy. Therefore the purpose of this review is to provide an up-to-date appreciation of the current state of TMR and its future developmental directions on CAD treatment. The current potential of this therapy focuses on the implementation of stem cells, in order to create a synergistic angiogenic effect while increasing myocardial repair and regeneration. Although TMR procedures provide increased vascularization within the myocardium, patients suffering from ischemic cardiomyopathy may not benefit from angiogenesis alone. Therefore, the goal of introducing stem cells is to restore the functional state of a failing heart by providing these cells with a favorable microenvironment that will enhance stem cell engraftment.
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Affiliation(s)
- Jessika Iwanski
- Department of Pharmacology, University of Arizona College of Medicine, Tucson, AZ USA ; Department of Surgery, Division of Cardiothoracic Surgery, University of Arizona College of Medicine, P.O. Box 245071, 1501N. Campbell Avenue, Tucson, AZ 85724-5071 USA
| | - Raymond K Wong
- Department of Pharmacology, University of Arizona College of Medicine, Tucson, AZ USA
| | - Douglas F Larson
- Department of Surgery, Division of Cardiothoracic Surgery, University of Arizona College of Medicine, P.O. Box 245071, 1501N. Campbell Avenue, Tucson, AZ 85724-5071 USA
| | - Alice S Ferng
- Department of Surgery, Division of Cardiothoracic Surgery, University of Arizona College of Medicine, P.O. Box 245071, 1501N. Campbell Avenue, Tucson, AZ 85724-5071 USA ; Department of Physiological Sciences, University of Arizona College of Medicine, Tucson, AZ USA
| | - Raymond B Runyan
- Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ USA
| | | | - Zain Khalpey
- Department of Surgery, Division of Cardiothoracic Surgery, University of Arizona College of Medicine, P.O. Box 245071, 1501N. Campbell Avenue, Tucson, AZ 85724-5071 USA ; Department of Physiological Sciences, University of Arizona College of Medicine, Tucson, AZ USA ; Banner University Medical Center, 1501N. Campbell Avenue, Room 4302A, Tucson, AZ 85724 USA ; Medical Research Building, 1656 E. Mabel St, Rm 120, Tucson, AZ USA
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Wei C, Zhu X, Wang F, Xu Y, Balakrishnan K, Song F, Norwood RA, Peyghambarian N. Graphene Q-switched 2.78 μm Er3+-doped fluoride fiber laser. OPTICS LETTERS 2013; 38:3233-3236. [PMID: 23988922 DOI: 10.1364/ol.38.003233] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report a diode-pumped 2.78 μm Er3+-doped ZBLAN fiber laser passively Q switched by a graphene saturable absorber, which was directly deposited onto a fiber dichroic mirror by the method of optically driven deposition. Stable Q-switched operation with a pulse duration of 2.9 μs and a pulse energy of 1.67 μJ was achieved in a 10 m long gain fiber. The pulse duration was reduced to 1 μs when the gain fiber length was shortened to 2 m. This Letter demonstrates that graphene is a promising and reliable saturable absorber for mid-infrared pulse generation at 3 μm.
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Affiliation(s)
- Chen Wei
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
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Lapotko D. Plasmonic nanoparticle-generated photothermal bubbles and their biomedical applications. Nanomedicine (Lond) 2010; 4:813-45. [PMID: 19839816 DOI: 10.2217/nnm.09.59] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
This article is focused on the optical generation and detection of photothermal vapor bubbles around plasmonic nanoparticles. We report physical properties of such plasmonic nanobubbles and their biomedical applications as cellular probes. Our experimental studies of gold nanoparticle-generated photothermal bubbles demonstrated the selectivity of photothermal bubble generation, amplification of optical scattering and thermal insulation effect, all realized at the nanoscale. The generation and imaging of photothermal bubbles in living cells (leukemia and carcinoma culture and primary cancerous cells), and tissues (atherosclerotic plaque and solid tumor in animal) demonstrated a noninvasive highly sensitive imaging of target cells by small photothermal bubbles and a selective mechanical, nonthermal damage to the individual target cells by bigger photothermal bubbles due to a rapid disruption of cellular membranes. The analysis of the plasmonic nanobubbles suggests them as theranostic probes, which can be tuned and optically guided at cell level from diagnosis to delivery and therapy during one fast process.
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Affiliation(s)
- Dmitri Lapotko
- AV Lykov Heat & Mass Transfer Institute, Minsk 220072, Belarus.
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Lukianova-Hleb EY, Mrochek AG, Lapotko DO. Method for disruption and re-canalization of atherosclerotic plaques in coronary vessels with photothermal bubbles generated around gold nanoparticles. Lasers Surg Med 2009; 41:240-7. [DOI: 10.1002/lsm.20749] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Nandakumar K, Obika H, Sreekumari K, Utsumi A, Ooie T, Yano T. Laser damage to marine plankton and its application to checking biofouling and invasion by aquatic species: a laboratory study. BIOFOULING 2009; 25:95-98. [PMID: 19021017 DOI: 10.1080/08927010802546004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this laboratory study, the ability of low-power pulsed laser irradiation to kill planktonic organisms in a flowing water system was examined, thus, to test the possibility of using this technique as a water treatment strategy to reduce biofouling growth in condenser tubes of power plants and to reduce bioinvasion via the ballast water of ships. Two flow rates (4.6 and 9.0 l h(-1)) were tested on three planktonic organisms: two marine centric diatoms viz. Skeletonema costatum and Chaetoceros gracilis and a dinoflagellate, Heterocapsa circularisquama. A low-power pulsed laser irradiation at 532 nm with a fluence of 0.1 J cm(-2) from a frequency-doubled Nd:YAG laser was used as the irradiation source. The laser irradiation resulted in a heavy mortality of the test cells. The mortality observed was >90% for S. costatum and H. circularisqama and >70% for C. gracilis. The results suggest that laser irradiation has the potential to act as a water treatment strategy to reduce biofouling of condenser tubes in power plants as well as to reduce species invasion via the ballast water of ships.
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Affiliation(s)
- Kanavillil Nandakumar
- Marine Eco-Materials Research Group, National Institute of Advanced Industrial Science and Technology, Shikoku Marine Resources and Environment Research Institute, Takamatsu, Kagawa, Japan.
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Le DE, Powers ER, Bin JP, Leong-Poi H, Goodman NC, Kaul S. Transmyocardial revascularization ameliorates ischemia by attenuating paradoxical catecholamine-induced vasoconstriction. J Nucl Cardiol 2007; 14:207-14. [PMID: 17386383 PMCID: PMC1865521 DOI: 10.1016/j.nuclcard.2006.12.328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 12/22/2006] [Accepted: 12/22/2006] [Indexed: 11/29/2022]
Abstract
BACKGROUND The mechanism by which transmyocardial revascularization (TMR) offers clinical benefit is controversial. We hypothesized that TMR ameliorates ischemia by reversing paradoxical catecholamine-induced vasoconstriction. METHODS AND RESULTS Chronic ischemic cardiomyopathy was created in 11 dogs by placing ameroid constrictors on the proximal coronary arteries and their major branches. Six weeks later, 35 channels were created percutaneously in the left circumflex artery region, with the left anterior descending artery region serving as control. At rest, wall thickening and myocardial blood flow did not change in the treated region, whereas they deteriorated in the control bed. Contractile and myocardial blood flow reserve increased in the treated region but deteriorated in the control region. There was diminished iodine 123 metaiodobenzylguanidine uptake and a significant reduction in noradrenergic nerves in the treated region compared with the control region, with a corresponding reduction in tissue tyrosine hydroxylase activity. CONCLUSIONS We conclude that the absence of a catecholamine-induced reduction in MBF reserve and contractile reserve in the TMR-treated region with associated evidence of neuronal injury indicates that the relief of exercise-induced ischemia after TMR most likely results from reversal of paradoxical catecholamine-induced vasoconstriction. These findings may have implications in selecting patients who would benefit from TMR.
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Nandakumar K, Keeler W, Schraft H, Leung KT. Visible laser and UV-A radiation impact on a PNP degrading Moraxella strain and its rpoS mutant. Biotechnol Bioeng 2006; 94:793-802. [PMID: 16489628 DOI: 10.1002/bit.20898] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The role of stationary phase sigma factor gene (rpoS) in the stress response of Moraxella strain when exposed to radiation was determined by comparing the stress responses of the wild-type (WT) and its rpoS knockout (KO) mutant. The rpoS was turned on by starving the WT cultures for 24 h in minimal salt medium. Under non-starved condition, both WT and KO planktonic Moraxella cells showed an increase in mortality with the increase in duration of irradiation. In the planktonic non-starved Moraxella, for the power intensity tested, UV radiation caused a substantially higher mortality rate than did by the visible laser light (the mortality rate observed for 15-min laser radiation was 53.4 +/- 10.5 and 48.7 +/- 8.9 for WT and KO, respectively, and 97.6 +/- 0 and 98.5 +/- 0 for 25 s of UV irradiation in WT and KO, respectively). However, the mortality rate decreased significantly in the starved WT when exposed to these two radiations. In comparison, rpoS protected the WT against the visible laser light more effectively than it did for the UV radiation. The WT and KO strains of Moraxella formed distinctly different types of biofilms on stainless steel coupons. The KO strain formed a denser biofilm than did the WT. Visible laser light removed biofilms from the surfaces more effectively than did the UV. This was true when comparing the mortality of bacteria in the biofilms as well. The inability of UV radiation to penetrate biofilms due to greater rates of surface absorption is considered to be the major reason for the weaker removal of biofilms in comparison to that of the visible laser light. This result suggests that high power visible laser light might be an effective tool for the removal of biofilms.
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Affiliation(s)
- Kanavillil Nandakumar
- Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada
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Nandakumar K, Obika H, Utsumi A, Ooie T, Yano T. Molecular level damages of low power pulsed laser radiation in a marine bacterium Pseudoalteromonas carrageenovora. Lett Appl Microbiol 2006; 42:521-6. [PMID: 16620213 DOI: 10.1111/j.1472-765x.2006.01897.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To study the molecular level damages in a marine bacterium, Pseudoalteromonas carrageenovora, exposed to low power pulsed laser radiation from an Nd:YAG laser. METHODS AND RESULTS The laser damages in bacterial DNA were monitored by studying the formation of apurinic/apyrimidinic (AP) sites. Molecular probe kits were used for this purpose. Occurrence of lesions in the cell walls was monitored under a transmission electron microscope (TEM). The results showed that laser radiation significantly increased the number of AP sites in the bacterial DNA. This increase corresponded to the laser fluence (J cm(-2)) and to the duration of laser irradiation. TEM observation showed the occurrence of lesions in bacterial cell walls upon laser irradiation. CONCLUSIONS It is concluded that bacteria exposed to laser irradiation suffers DNA damages and resulted in broken cell walls. These events led to bacterial mortality. These are in addition to the mechanisms reported earlier such as the photochemical reactions occurring inside the cells upon exposure to low power laser. SIGNIFICANCE AND IMPACT OF THE STUDY These results help us to understand the mechanisms of bacterial mortality on exposure to low power pulsed laser irradiation and are useful in formulating a laser treatment strategy to kill bacteria.
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Affiliation(s)
- K Nandakumar
- Department of Biology, Lakehead University, Thunder Bay, ON, Canada.
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Nandakumar K, Obika H, Utsumi A, Ooie T, Yano T. In vitro laser ablation of natural marine biofilms. Appl Environ Microbiol 2004; 70:6905-8. [PMID: 15528562 PMCID: PMC525111 DOI: 10.1128/aem.70.11.6905-6908.2004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Accepted: 05/31/2004] [Indexed: 11/20/2022] Open
Abstract
We studied the efficiency of pulsed low-power laser irradiation of 532 nm from an Nd:YAG (neodymium-doped yttrium-aluminum-garnet) laser to remove marine biofilm developed on titanium and glass coupons. Natural biofilms with thicknesses of 79.4 +/- 27.8 microm (titanium) and 107.4 +/- 28.5 microm (glass) were completely disrupted by 30 s of laser irradiation (fluence, 0.1 J/cm2). Laser irradiation significantly reduced the number of diatoms and bacteria in the biofilm (paired t test; P < 0.05). The removal was better on titanium than on glass coupons.
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Affiliation(s)
- Kanavillil Nandakumar
- Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada.
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Nandakumar K, Obika H, Utsumi A, Ooie T, Yano T. In vitro laser ablation of laboratory developed biofilms using an Nd:YAG laser of 532 nm wavelength. Biotechnol Bioeng 2004; 86:729-36. [PMID: 15162448 DOI: 10.1002/bit.10829] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied the laser ablation of laboratory-developed biofilm on titanium and glass surfaces. Specifically, Pseudoalteromonas carrageenovora, a marine biofilm forming bacterium was used to generate laboratory biofilm. Two fluences, 0.05 and 0.1 J/cm(2) and three durations of irradiation, 30 s, 5 min, and 10 min were tested using an Nd;YAG laser of 532 nm wavelength (in the green light area). Nonirradiated coupons with biofilm served as control. The biofilm removal efficiency increased with the increase in laser fluence and duration of irradiation. The maximum biofilm area cover on control coupons of glass and titanium was 62.5 and 76.0%, respectively. Upon irradiation with fluence 0.1 J/cm(2) for the very short duration of 30 s, this reduced to 5.6 and 12.4% and at 10 min to 2.17 and 0.7% on glass and titanium coupons, respectively, while the controls did not show any reductions (62.5 and 76.0% respectively, for glass and titanium coupons). The biofilm TRC (Total Resuscitated Cells) reduction during this period was even more prominent than the area cover, indicating that the remaining biofilm portions on coupons after irradiation were largely composed of dead bacterial cells. The TRC in the irradiation chamber medium for short durations of irradiation showed a significant increase, indicating that the laser irradiation removed live bacteria from the biofilm. The re-growth of the resuscitated cells showed they could grow like the control cells but with a significant lag. The laser's efficiency in the removal of biofilm was better seen on titanium coupons than on glass. Our results showed that a low-power pulsed laser irradiation could be used to remove biofilm formed on hard surfaces.
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Affiliation(s)
- Kanavillil Nandakumar
- Marine Eco-materials Research Group, National Institute of Advanced Industrial Science and Technology (AIST), Marine Resources and Environment Research Institute 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan.
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Jun JH, Harris JL, Humphrey JD, Rastegar S. Effect of thermal damage and biaxial loading on the optical properties of a collagenous tissue. J Biomech Eng 2003; 125:540-8. [PMID: 12968579 DOI: 10.1115/1.1591202] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Thermal denaturation can induce marked changes in the optical and mechanical properties of collagenous tissues. The optical properties are important in both therapeutic and diagnostic applications of lasers in medicine. Although mechanical stress can be caused by collagen shrinkage in laser-based therapies, how the mechanical loading state affects the optical properties is not well understood. We used a new computer-controlled biaxial testing system to subject bovine epicardium to various loading conditions both before and after multiple levels of thermal damage. An integrating sphere technique was used to measure transmittance and diffuse reflectance, from which absorption and scattering coefficients were calculated using a Monte Carlo method. Results showed that the scattering coefficient increased with increasing mechanical load but decreased as the degree of thermal damage increased. There was no significant change in the absorption coefficient due to thermal damage over the ranges studied.
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Affiliation(s)
- J H Jun
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA
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Nandakumar K, Shinozaki T, Obika H, Ooie T, Utsumi A, Yano T. Impact of pulsed Nd:YAG laser on the marine biofilm-forming bacteria Pseudoalteromonas carrageenovora: significance of physiological status. Can J Microbiol 2002; 48:326-32. [PMID: 12030705 DOI: 10.1139/w02-028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The impact of pulsed Nd:YAG (neodymium-doped yttrium/aluminium garnet) laser irradiation on the marine biofilm-forming bacteria Pseudoalteromonas carrageenovora during two growth stages (log phase and stationary phase) and under two stresses (reduced temperature and nutrient limitation) was investigated. Bacteria were exposed to a laser fluence of 0.1 J x cm(-2) for 5, 10, and 15 min with a peak power of 20 MW x cm(-2), a pulse width of 5 ns, and an average power of 1 W x cm(-2) with a repetition rate of 10 Hz. The mortality of bacteria immediately after the irradiation as well as after a set period of time was determined. Mortality was higher among log-phase bacteria (72%) than bacteria in the stationary phase (51%) and those grown under nutrient limitation (51%). Bacteria grown at reduced temperature had a mortality of 49%. However, the differences in cell density of log-phase, stationary-phase, nutrient-limited, and low-temperature irradiated samples compared with controls after 5 h of incubation were 96, 93, 94, and 86%, respectively. The mortality values suggest that the same laser fluence has different degrees of effectiveness, depending on the physiological state of the bacteria.
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Affiliation(s)
- Kanavillil Nandakumar
- Marine Eco-materials Research Group, National Institute of Advanced Industrial Science and Technology (AIST), Marine Resources and Environment Research Institute, Kagawa, Japan.
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Ward GD, Watson IA, Stewart-Tull DE, Wardlaw AC, Wang RK, Nutley MA, Cooper A. Bactericidal action of high-power Nd:YAG laser light on Escherichia coli in saline suspension. J Appl Microbiol 2000; 89:517-25. [PMID: 11021585 DOI: 10.1046/j.1365-2672.2000.01144.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Infra-red light (1064 nm) from a high-power Nd:YAG laser caused more than 90% loss of viability of Escherichia coli during exposures that raised the temperature of PBS suspensions of the bacteria to 50 C in a thermocouple-equipped cuvette. In contrast, there was minimal loss of viability after heating the same suspensions to 50 degrees C in a water-bath, or in a PCR thermal cycler. The mechanism of laser killing at 50 degrees C was explored by differential scanning calorimetry, by laser treatment of transparent and turbid bacterial suspensions, and by optical absorbency studies of E. coli suspensions at 1064 nm. Taken together, the data suggested that the bactericidal action of Nd:YAG laser light at 50 degrees C was due partly to thermal heating and partly to an additional, as yet undefined, mechanism. Scanning electron microscopy revealed localized areas of surface damage on laser-exposed E. coli cells.
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Affiliation(s)
- G D Ward
- Microbiology Department, Vinamul Ltd, Carshalton, Surrey, UK
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Hughes GC, Kypson AP, Annex BH, Yin B, St Louis JD, Biswas SS, Coleman RE, DeGrado TR, Donovan CL, Landolfo KP, Lowe JE. Induction of angiogenesis after TMR: a comparison of holmium: YAG, CO2, and excimer lasers. Ann Thorac Surg 2000; 70:504-9. [PMID: 10969671 DOI: 10.1016/s0003-4975(00)01569-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND Transmyocardial laser revascularization (TMR) is an emerging treatment for end-stage coronary artery disease. A variety of lasers are currently available to perform the procedure, although their relative efficacy is unknown. The purpose of this study was to compare changes in myocardial blood flow and function 6 months after TMR with holmium:yttrium-aluminum-garnet (holmium:YAG), carbon dioxide (CO2), and xenon chloride excimer lasers in a model of chronic ischemia. METHODS Miniswine underwent subtotal (90%) left circumflex coronary stenosis. Baseline positron emission tomography and dobutamine stress echocardiography were performed to document hibernating myocardium in the left circumflex coronary artery distribution. Animals were then randomized to sham redo-thoracotomy (n = 5) or TMR using a holmium:YAG (n = 5), CO2 (n = 5) or excimer (n = 5) laser. Six months postoperatively, the positron emission tomography and dobutamine stress echocardiography studies were repeated and the animals sacrificed. RESULTS In animals undergoing TMR with holmium: YAG and CO2 lasers, a significant improvement in myocardial blood flow to the lased left circumflex regions was seen. No significant change in myocardial blood flow was seen in sham- or excimer-lased animals. There was a significant improvement in regional stress function of the lased segments 6 months postoperatively in animals undergoing holmium:YAG and CO2 laser TMR that was consistent with a reduction in ischemia. There was no change in wall motion in sham- or excimer-lased animals. Significantly greater neovascularization was observed in the holmium:YAG and CO2 lased regions than with either the sham procedure or excimer TMR. CONCLUSIONS Transmyocardial laser revascularization with either holmium:YAG or CO2 laser improves myocardial blood flow and contractile reserve in lased regions 6 months postoperatively. These changes were not seen following excimer TMR or sham thoracotomy, suggesting that differences in laser energy or wavelength or both may be important in the induction of angiogenesis.
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Affiliation(s)
- G C Hughes
- Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Hayashi J, Saito T, Aizawa K. Change in chemical composition of lipids accumulated in atheromas of rabbits following photodynamic therapy. Lasers Surg Med Suppl 2000; 21:287-93. [PMID: 9291086 DOI: 10.1002/(sici)1096-9101(1997)21:3<287::aid-lsm9>3.0.co;2-m] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND OBJECTIVE Mono-L-aspartyl chlorin e6 (NPe6) has been used in the photodynamic therapy of neoplasms. This substance has been shown to accumulate in atheroma of rabbits. We evaluated the change in the lipid components of atheromas after photodynamic therapy with NPe6 using Fourier transform infrared (FTIR) microspectroscopy. STUDY DESIGN/MATERIALS AND METHODS Rabbits were fed a cholesterol-rich diet for 20 weeks. Six hours after they were administered NPe6 (2 mg/kg), the atheroma present on the abdominal aorta was irradiated with a diode laser with 100 J/cm2 or 200 J/ cm2 of the tissue fluence. Tissue samples were prepared for FTIR and histological analysis. RESULTS Specimens of atheroma from the untreated animals appeared as fatty streaks whose infrared spectra exhibited characteristic peaks at 1,738(-1) cm-1, 1,468 cm-1, 1,380 cm-1, and 1,174 cm-1, indicating the accumulation of cholesterol ester. Seven days after photodynamic therapy, FTIR microspectroscopic analysis showed a marked decrease in the peak intensity in the treated atheroma related to the =C=O ester bond at 1738 cm-1 with no concomitant increase in the intensity of the peaks related to free cholesterol. CONCLUSION Findings suggest a dissociation of ester bonds and the depletion of cholesterol esters in the atheromas after photodynamic therapy with NPe6. The lipids accumulated in the atheroma were perhaps decreased or destroyed following such treatment.
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Affiliation(s)
- J Hayashi
- Department of Medicine & Gerontology, School of Medicine, Kyorin University, Tokyo, Japan
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19
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Hughes GC, Shah AS, Yin B, Shu M, Donovan CL, Glower DD, Lowe JE, Landolfo KP. Early postoperative changes in regional systolic and diastolic left ventricular function after transmyocardial laser revascularization: a comparison of holmium:YAG and CO2 lasers. J Am Coll Cardiol 2000; 35:1022-30. [PMID: 10732904 DOI: 10.1016/s0735-1097(99)00645-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES The purpose of this study was to determine the short-term effects of transmyocardial laser revascularization (TMR) on regional left ventricular systolic and diastolic function, myocardial blood flow (MBF) and myocardial water content (MWC). BACKGROUND Clinical studies of TMR have noted a significant incidence of cardiac complications in the early postoperative period. However, the early post-treatment effects of laser therapy on the myocardium and their potential contribution to postoperative cardiac morbidity are unknown. METHODS Swine underwent holmium:yttrium-aluminum-garnet (holmium:YAG) (n = 12) or carbon dioxide (CO2) (n = 12) laser TMR. Regional systolic function for the lased and nonlased regions was quantitated using preload recruitable work area (PRWA) and regional diastolic function with the ventricular stiffness constant alpha. RESULTS Preload recruitable work area was significantly decreased in the lased regions both 1 (59.8+/-13.0% of baseline, p = 0.02) and 6 h (64.2+/-9.4% of baseline, p = 0.02) after holmium:YAG TMR. This decreased PRWA was associated with a significant reduction in MBF to the lased regions (13.2% reduction at 1 h, p = 0.02; 18.4% decrease at 6 h post-TMR, p = 0.01). These changes were not seen after CO2 laser TMR. A significant increase in MWC (1.4+/-0.3% increase with holmium:YAG, p = 0.004; 1+/-0.2% increase with CO2, p = 0.002) and alpha (217.4+/-44.2% of baseline 6 h post-holmium:YAG TMR, p = 0.05; 206+/-36.7% of baseline 6 h post-CO2 TMR, p = 0.03) was seen after TMR with both lasers. CONCLUSIONS In the early postoperative setting, impaired regional systolic function in association with regional ischemia is seen after TMR with a holmium:YAG laser. Both holmium:YAG and CO2 lasers are associated with increased MWC and impaired diastolic relaxation in the lased regions. These changes may explain the significant incidence of early postoperative cardiac morbidity. The impact of these findings on anginal relief and long-term outcome are not known.
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Affiliation(s)
- G C Hughes
- Duke University Medical Center, Durham, North Carolina 27710, USA.
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Marcu L, Grundfest WS, Maarek JMI. Photobleaching of Arterial Fluorescent Compounds: Characterization of Elastin, Collagen and Cholesterol Time-resolved Spectra during Prolonged Ultraviolet Irradiation. Photochem Photobiol 1999. [DOI: 10.1111/j.1751-1097.1999.tb03352.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nilsson AM, Heinrich D, Olajos J, Andersson-Engels S. Near infrared diffuse reflection and laser-induced fluorescence spectroscopy for myocardial tissue characterisation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 1997; 53A:1901-12. [PMID: 9375415 DOI: 10.1016/s1386-1425(97)00106-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In order to evaluate the potential of cardiovascular tissue characterisation using near-infrared (NIR) spectroscopy, spectra in a previously unexplored wavelength region 0.8-2.3 micron were recorded from various pig heart tissue samples in vitro: normal myocardium (with and without endo/epicardium), aorta, fatty and fibrous heart tissue. The spectra were analysed with principal component analysis (PCA), revealing several spectroscopically characteristic features enabling tissue classification. Several of the identified spectral features could be attributed to specific tissue constituents by comparing the tissue signals with spectra obtained from water, elastin, collagen and cholesterol as well as with published data. The results obtained with the NIR spectroscopy technique in terms of its potential to classify different tissue types were compared with those from laser-induced fluorescence (LIF) using 337 nm excitation. LIF and NIR spectroscopy can in combination with PCA be used to discriminate between all previously mentioned tissue groups, apart from fatty versus fibrous tissue (LIF) and aorta versus fibrous tissue (NIR), respectively. The NIR analysis was improved by focusing the PCA to the wavelength segment 2.0-2.3 microns, resulting in successful spectral characterisation of all cardiovascular tissue groups.
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Affiliation(s)
- A M Nilsson
- Department of Physics, Lund Institute of Technology, Sweden.
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22
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Abstract
For medical applications, the choice of a delivery system will be governed by the characteristics of the laser system on the one hand and the tissue application on the other. The most important parts are the beam guide and the target optics. Most lasers have wavelengths in the visible and near-infrared and can be transported by silica fibres. For the mid- and far-IR other fibre materials or hollow waveguides are used. At the end of the waveguide or fibre, an optically active component is present to direct the beam and to control the power density on the target tissue. The laser beam can be delivered either by focusing handpieces and scanning devices to treat superficial areas or through microscopes, endoscopes and flexible fibres to treat areas almost anywhere inside the human body. The characteristics of the delivery systems can be determined looking at beam properties, transmission and thermal properties. The delivery of continuous wave or pulsed laser energy, contact or non-contact, will determine the contribution of optical, thermal and mechanical effects to the tissue. The practical use of laser delivery systems is illustrated by various clinical applications.
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Affiliation(s)
- R M Verdaasdonk
- Department of Biomedical Engineering and Clinical Physics, University Hospital Utrecht, The Netherlands
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23
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Andersson-Engels S, Klinteberg C, Svanberg K, Svanberg S. In vivo fluorescence imaging for tissue diagnostics. Phys Med Biol 1997; 42:815-24. [PMID: 9172261 DOI: 10.1088/0031-9155/42/5/006] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Non-invasive fluorescence imaging has the potential to provide in vivo diagnostic information for many clinical specialties. Techniques have been developed over the years for simple ocular observations following UV excitation to sophisticated spectroscopic imaging using advanced equipment. Much of the impetus for research on fluorescence imaging for tissue diagnostics has come from parallel developments in photodynamic therapy of malignant lesions with fluorescent photosensitizers. However, the fluorescence of endogenous molecules (tissue autofluorescence) also plays an important role in most applications. In this paper, the possibilities of imaging tissues using fluorescence spectroscopy as a mean of tissue characterization are discussed. The various imaging techniques for extracting diagnostic information suggested in the literature are reviewed. The development of exogenous fluorophores for this purpose is also presented. Finally, the present status of clinical evaluation and future directions are discussed.
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Gassler N, Wintzer HO, Stubbe HM, Wullbrand A, Helmchen U. Transmyocardial laser revascularization. Histological features in human nonresponder myocardium. Circulation 1997; 95:371-5. [PMID: 9008451 DOI: 10.1161/01.cir.95.2.371] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The creation of transmyocardial channels from the epicardium to the left ventricular cavity with the use of a CO2 laser is a modern approach in the treatment of patients with chronic ischemic cardiac disease. The histological features of human myocardium at different times after transmyocardial laser therapy have not been previously described. We had the opportunity to examine hearts from patients who died without clinical evidence of a persistent therapeutic effect at 3, 16, and 150 days after transmyocardial laser revascularization (TMR) respectively. METHODS AND RESULTS We grossly localized the laser-created channels in unfixed and formalin-fixed tissue. Three ventricular levels were defined for cutting the hearts into four segments. Then, transmural blocks were excised and cut crosswise and lengthwise for histological investigation through the use of established staining methods. On day 3, laser-induced channels were filled with abundant granulocytes and thrombocytes, fibrinous network, and detritus and were surrounded by severe myocardial necrosis. Furthermore, the epicardial and endocardial portions were obstructed by fibrinous network and microclots. Granulocytes were mostly absent on day 16; in addition, the channels were filled with erythrocytes or fibrinous network. On day 150, we observed a string of cicatricial tissue admixed with a polymorphous blood-filled capillary network and small veins, which very rarely had a continuous wrinkled link to the left ventricular cavity. CONCLUSIONS We found different stages of wound healing in human nonresponder myocardium after TMR, resulting in scarred tissue that displayed capillary network and dilated venules without evidence of patent and endothelialized laser-created channels. Experimental studies are necessary to analyze the morphological basis for TMR-mediated effects in human responder myocardium.
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Affiliation(s)
- N Gassler
- Department of Pathology, University Hospital Eppendorf, Hamburg, Germany
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25
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Topaz O, Rozenbaum EA, Schumacher A, Luxenberg MG. Solid-state mid-infrared laser facilitated coronary angioplasty: clinical and quantitative coronary angiographic results in 112 patients. Lasers Surg Med 1996; 19:260-72. [PMID: 8923422 DOI: 10.1002/(sici)1096-9101(1996)19:3<260::aid-lsm2>3.0.co;2-q] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND AND OBJECTIVE Holmium:YAG is a solid-state, investigational coronary laser device. Preliminary reports indicate the clinical potential for this laser; however, its safety and efficacy in a single center experience have not yet been reported and analyzed in detail. STUDY DESIGN, PATIENTS, AND METHODS One hundred and twelve consecutive symptomatic patients underwent percutaneous holmium:YAG laser (2.1 micron wavelength, 250-600 mJ/pulse, 5 Hz) facilitated coronary angioplasty. Sixty-six patients (Gr 1) had 74 thrombotic lesions, and 46 patients (Gr 2) had 55 thrombus-free stenoses. RESULTS Overall laser success was achieved in 120 out of 129 lesions (93%), with 95% subsequent balloon angioplasty success. Laser and clinical successes among the two groups were similar. By quantitative coronary angiography, reduction in the percent diameter stenosis (mean +/- SD) was similar (79 +/- 16% to 37 +/- 14% vs. 73 +/- 16% to 37 +/- 11.5%; P = NS) in both groups. However, minimal luminal diameter improved significantly more in Gr 1 patients, (0.7 +/- 0.5 mm to 2.0 +/- 0.5 mm, vs. 0.9 +/- 0.4 mm to 1.8 +/- 0.4 mm, P = 0.03). Angiographic and clinical complications were similar in patients with thrombus and without thrombus. No death, perforation, or Q-wave infarction occurred in the catheterization laboratory in either group. In-hospital mortality occurred in two patients from cardiac causes unrelated to the laser application. Of the 98 patients who reached the 6 month anniversary, 76 (77%) remained asymptomatic. The restenosis rate among the patients who underwent repeat angiography was 50%. CONCLUSIONS Solid-state, mid-infrared laser can be safely and successfully applied to symptomatic patients with thrombotic and nonthrombotic lesions. Similar to other debulking devices, the effectiveness of this laser in yielding long-term patency has not been proved.
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Affiliation(s)
- O Topaz
- Cardiac Catheterization Laboratories, St. Paul-Ramsey Medical Center, University of Minnesota Medical School 23249, USA
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Hielscher AH, Jacques SL, Wang L, Tittel FK. The influence of boundary conditions on the accuracy of diffusion theory in time-resolved reflectance spectroscopy of biological tissues. Phys Med Biol 1995; 40:1957-75. [PMID: 8587943 DOI: 10.1088/0031-9155/40/11/013] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The applicability of diffusion theory for the determination of tissue optical properties from time-resolved reflectance spectroscopy is investigated. Analytical expressions from diffusion theory using the three most commonly assumed boundary conditions at the air-tissue interface are compared with time-resolved Monte Carlo simulations and measurements on tissue phantoms. The effects of the choice of the boundary conditions on the accuracy of the findings for the optical parameters are quantified, and criteria for accurate curve-fitting algorithms are developed.
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Affiliation(s)
- A H Hielscher
- Department of Electrical and Computer Engineering, Rice University, Houston, TX 77005-1892, USA
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