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Cornelius NR, Nishimura N, Suh M, Schwartz TH, Doerschuk PC. A mathematical model relating cortical oxygenated and deoxygenated hemoglobin flows and volumes to neural activity. J Neural Eng 2015; 12:046013. [PMID: 26045465 DOI: 10.1088/1741-2560/12/4/046013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To describe a toolkit of components for mathematical models of the relationship between cortical neural activity and space-resolved and time-resolved flows and volumes of oxygenated and deoxygenated hemoglobin motivated by optical intrinsic signal imaging (OISI). APPROACH Both blood flow and blood volume and both oxygenated and deoxygenated hemoglobin and their interconversion are accounted for. Flow and volume are described by including analogies to both resistive and capacitive electrical circuit elements. Oxygenated and deoxygenated hemoglobin and their interconversion are described by generalization of Kirchhoff's laws based on well-mixed compartments. MAIN RESULTS Mathematical models built from this toolkit are able to reproduce experimental single-stimulus OISI results that are described in papers from other research groups and are able to describe the response to multiple-stimuli experiments as a sublinear superposition of responses to the individual stimuli. SIGNIFICANCE The same assembly of tools from the toolkit but with different parameter values is able to describe effects that are considered distinctive, such as the presence or absence of an initial decrease in oxygenated hemoglobin concentration, indicating that the differences might be due to unique parameter values in a subject rather than different fundamental mechanisms.
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Chen HJ, Sun J, Huang Z, Hou H, Arcilla M, Rakhilin N, Joe DJ, Choi J, Gadamsetty P, Milsom J, Nandakumar G, Longman R, Zhou XK, Edwards R, Chen J, Chen KY, Bu P, Wang L, Xu Y, Munroe R, Abratte C, Miller AD, Gümüş ZH, Shuler M, Nishimura N, Edelmann W, Shen X, Lipkin SM. Comprehensive models of human primary and metastatic colorectal tumors in immunodeficient and immunocompetent mice by chemokine targeting. Nat Biotechnol 2015; 33:656-60. [PMID: 26006007 PMCID: PMC4532544 DOI: 10.1038/nbt.3239] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 04/15/2015] [Indexed: 11/09/2022]
Abstract
Current orthotopic xenograft models of human colorectal cancer (CRC) require surgery and do not robustly form metastases in the liver, the most common site clinically. CCR9 traffics lymphocytes to intestine and colorectum. We engineered use of the chemokine receptor CCR9 in CRC cell lines and patient-derived cells to create primary gastrointestinal (GI) tumors in immunodeficient mice by tail-vein injection rather than surgery. The tumors metastasize inducibly and robustly to the liver. Metastases have higher DKK4 and NOTCH signaling levels and are more chemoresistant than paired subcutaneous xenografts. Using this approach, we generated 17 chemokine-targeted mouse models (CTMMs) that recapitulate the majority of common human somatic CRC mutations. We also show that primary tumors can be modeled in immunocompetent mice by microinjecting CCR9-expressing cancer cell lines into early-stage mouse blastocysts, which induces central immune tolerance. We expect that CTMMs will facilitate investigation of the biology of CRC metastasis and drug screening.
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Santisakultarm TP, Paduano CQ, Stokol T, Southard TL, Nishimura N, Skoda RC, Olbricht WL, Schafer AI, Silver RT, Schaffer CB. Stalled cerebral capillary blood flow in mouse models of essential thrombocythemia and polycythemia vera revealed by in vivo two-photon imaging. J Thromb Haemost 2014; 12:2120-30. [PMID: 25263265 DOI: 10.1111/jth.12738] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Indexed: 02/01/2023]
Abstract
BACKGROUND Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) that share the JAK2(V617F) mutation in hematopoietic stem cells, leading to excessive production of predominantly platelets in ET, and predominantly red blood cells (RBCs) in PV. The major cause of morbidity and mortality in PV and ET is thrombosis, including cerebrovascular occlusive disease. OBJECTIVES To identify the effect of excessive blood cells on cerebral microcirculation in ET and PV. METHODS We used two-photon excited fluorescence microscopy to examine cerebral blood flow in transgenic mouse models that mimic MPNs. RESULTS AND CONCLUSIONS We found that flow was 'stalled' in an elevated fraction of brain capillaries in ET (18%), PV (27%), mixed MPN (14%) and secondary (non-MPN) erythrocytosis (27%) mice, as compared with controls (3%). The fraction of capillaries with stalled flow increased when the hematocrit value exceeded 55% in PV mice, and the majority of stalled vessels contained only stationary RBCs. In contrast, the majority of stalls in ET mice were caused by platelet aggregates. Stalls had a median persistence time of 0.5 and 1 h in ET and PV mice, respectively. Our findings shed new light on potential mechanisms of neurological problems in patients with MPNs.
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Ohno H, Nishimura N, Yamada K, Shimizu Y, Nishimura R, Iwase S, Sugenoya J, Sato M. Water nanodroplets make a greater contribution to facial skin moisture levels in air-conditioned rooms during winter than in summer. Skin Res Technol 2014; 21:207-13. [DOI: 10.1111/srt.12178] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2014] [Indexed: 11/28/2022]
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80
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Davis AA, Farrar MJ, Nishimura N, Jin MM, Schaffer CB. Optoporation and genetic manipulation of cells using femtosecond laser pulses. Biophys J 2014; 105:862-71. [PMID: 23972838 DOI: 10.1016/j.bpj.2013.07.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 07/07/2013] [Accepted: 07/11/2013] [Indexed: 02/08/2023] Open
Abstract
Femtosecond laser optoporation is a powerful technique to introduce membrane-impermeable molecules, such as DNA plasmids, into targeted cells in culture, yet only a narrow range of laser regimes have been explored. In addition, the dynamics of the laser-produced membrane pores and the effect of pore behavior on cell viability and transfection efficiency remain poorly elucidated. We studied optoporation in cultured cells using tightly focused femtosecond laser pulses in two irradiation regimes: millions of low-energy pulses and two higher-energy pulses. We quantified the pore radius and resealing time as a function of incident laser energy and determined cell viability and transfection efficiency for both irradiation regimes. These data showed that pore size was the governing factor in cell viability, independently of the laser irradiation regime. For viable cells, larger pores resealed more quickly than smaller pores, ruling out a passive resealing mechanism. Based on the pore size and resealing time, we predict that few DNA plasmids enter the cell via diffusion, suggesting an alternative mechanism for cell transfection. Indeed, we observed fluorescently labeled DNA plasmid adhering to the irradiated patch of the cell membrane, suggesting that plasmids may enter the cell by adhering to the membrane and then being translocated.
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Ohshima Y, Yanagishita T, Ito K, Tamada Y, Nishimura N, Inukai Y, Iwase S, Watanabe D. A case of acquired idiopathic generalized anhidrosis in a 2-year-old infant. J Eur Acad Dermatol Venereol 2014; 29:1446-8. [PMID: 24698553 DOI: 10.1111/jdv.12499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/06/2014] [Accepted: 03/03/2014] [Indexed: 11/26/2022]
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82
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Shih AY, Nishimura N, Nguyen J, Friedman B, Lyden PD, Schaffer CB, Kleinfeld D. Optically induced occlusion of single blood vessels in rodent neocortex. Cold Spring Harb Protoc 2013; 2013:1153-60. [PMID: 24298038 DOI: 10.1101/pdb.prot079509] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ability to form targeted vascular occlusions in small vessels of the brain is an important technique for studying the microscopic basis of cerebral ischemia. We describe two complementary methods that enable targeted occlusion of any single blood vessel within the upper 500 µm of adult rodent neocortex. Our goal is to generate highly localized regions of ischemia by blocking penetrating arterioles and ascending venules, which are bottlenecks of flow in the cortical angioarchitecture. One method, termed photothrombosis, makes use of linear optical absorption by a photosensitizer, transiently circulated in the blood stream, to induce a clot in a surface or near-surface segment of a vessel. The second method, termed plasma-mediated ablation, makes use of nonlinear optical interactions, without the need to introduce an exogenous absorber, to induce clots in subsurface segments of penetrating vessels, as well as subsurface microvessels and capillaries. The choice of the method for occlusion of individual vessels depends on the location of the vessels being studied and the objectives of the study. Here we describe concurrent high resolution in vivo imaging and auxiliary laser setups, occlusion protocols, and post hoc histological procedures.
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Ouchi A, Yokoyama M, Takeuchi K, Nitta H, Ueda K, Nishimura N, Tsuyama N, Terui Y, Hatake K. GDP Chemotherapy for Relapsed/Refractory Lymphomas is Effective and Safe. Ann Oncol 2013. [DOI: 10.1093/annonc/mdt460.113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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84
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Nishimura N, Terui Y, Ouchi A, Ueda K, Nitta H, Yokoyama M, Tsuyama N, Takeuchi K, Hatake K. Incidence of Deep Vein Thrombosis (DVE) in Myeloma Patients Treated with Lenalidomide/ Dexamethasone with Prophylaxis. Ann Oncol 2013. [DOI: 10.1093/annonc/mdt459.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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85
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Nishimura N, Schaffer CB. Big effects from tiny vessels: imaging the impact of microvascular clots and hemorrhages on the brain. Stroke 2013; 44:S90-2. [PMID: 23709743 DOI: 10.1161/strokeaha.112.679621] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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86
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Nishimura N, Karino F, Ishihara N, Moriyama H, Miura K, Sutani A, Kuraki T, Ikawa K, Morikawa N, Naora K, Isobe T. P28 Pharmacodynamics, pharmacokinetics of piperacillin/tazobactam in Japanese elderly patients with nursing and healthcare-associated pneumonia. Int J Antimicrob Agents 2013. [DOI: 10.1016/s0924-8579(13)70273-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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87
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Huland DM, Charan K, Ouzounov DG, Jones JS, Nishimura N, Xu C. Three-photon excited fluorescence imaging of unstained tissue using a GRIN lens endoscope. BIOMEDICAL OPTICS EXPRESS 2013; 4:652-8. [PMID: 23667782 PMCID: PMC3646593 DOI: 10.1364/boe.4.000652] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/07/2013] [Accepted: 03/15/2013] [Indexed: 05/18/2023]
Abstract
We present a compact and portable three-photon gradient index (GRIN) lens endoscope system suitable for imaging of unstained tissues, potentially deep within the body, using a GRIN lens system of 1 mm diameter and 8 cm length. The lateral and axial resolution in water is 1.0 μm and 9.5 μm, respectively. The ~200 μm diameter field of view is imaged at 2 frames/s using a fiber-based excitation source at 1040 nm. Ex vivo imaging is demonstrated with unstained mouse lung at 5.9 mW average power. These results demonstrate the feasibility of three-photon GRIN lens endoscopy for optical biopsy.
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Yano T, Hatanaka H, Yamamoto H, Nakazawa K, Nishimura N, Wada S, Tamada K, Sugano K. Intraluminal injection of indigo carmine facilitates identification of the afferent limb during double-balloon ERCP. Endoscopy 2013; 44 Suppl 2 UCTN:E340-1. [PMID: 23012011 DOI: 10.1055/s-0032-1309865] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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89
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Ohshima Y, Yanagishita T, Ito K, Tamada Y, Nishimura N, Inukai Y, Iwase S, Sugenoya J, Watanabe D. Treatment of patients with acquired idiopathic generalized anhidrosis. Br J Dermatol 2012; 168:430-2. [PMID: 22709381 DOI: 10.1111/j.1365-2133.2012.11112.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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90
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Ohhara Y, Nishimura N, Nara E, Nakano K, Ueda K, Sakajiri S, Mishima Y, Yokoyama M, Terui Y, Takahashi S, Hatake K. Docetaxel Plus Cisplatin as First-Line Chemotherapy in Patients with Recurrent or Metastatic Head and Neck Cancer. Ann Oncol 2012. [DOI: 10.1016/s0923-7534(20)32354-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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91
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Nakano K, Takahashi S, Nishimura N, Mishima Y, Sakajiri S, Yokoyama M, Terui Y, Motoi N, Hatake K. Number of Involved Organs is Predictive Factor of Response to Cyvadic Chemotherapy for Advanced Soft Tissue Sarcoma Patients. Ann Oncol 2012. [DOI: 10.1016/s0923-7534(20)32372-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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92
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Uomori T, Yokoyama M, Nara E, Nakano K, Ueda K, Nishimura N, Sakajiri S, Mishima Y, Terui Y, Takahashi S. The Efficacy and Safety Analysis of Carbopratin and Paclitaxel Therapy for Patients with Inoperable, Recurrent or Refractory Adenocarcinoma of the Head and Neck. Ann Oncol 2012. [DOI: 10.1016/s0923-7534(20)32353-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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93
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Nishimura N, Yokoyama M, Ohhara Y, Nara E, Nakano K, Ueda K, Mishima Y, Sakajiri S, Terui Y, Takahashi S, Hatake K. TPF Induction Chemotherapy Followed by Cisplatin-Based Concurrent Chemoradiotherapy in Patients with Stage IV Head and Neck Cancer Demonstrated no Benefit. Ann Oncol 2012. [DOI: 10.1016/s0923-7534(20)32352-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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94
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Takemoto S, Pornkuna R, Nishimura N, Inoue Y, Sakai T, Harada N, Nagakura S, Hidaka M, Kiyokawa T, Haga Y, Kawano F. P065 Acute crisis of adult T-cell leukaemia following soluble CD30 elevation: Shedding of CD30 and CD25 from cell surface associated with the aggressiveness. Cytokine 2012. [DOI: 10.1016/j.cyto.2012.06.150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kuwahara Y, Tsukahara R, Iwase S, Nishimura N, Shimizu Y, Sugenoya J. 11. Relationships between skin sympathetic nerve activities and evoked potentials induced by voluntary or involuntary muscle contractions: Comparison between sudomotor and vasoconstrictor components. Clin Neurophysiol 2012. [DOI: 10.1016/j.clinph.2012.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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96
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Shih AY, Driscoll JD, Drew PJ, Nishimura N, Schaffer CB, Kleinfeld D. Two-photon microscopy as a tool to study blood flow and neurovascular coupling in the rodent brain. J Cereb Blood Flow Metab 2012; 32:1277-309. [PMID: 22293983 PMCID: PMC3390800 DOI: 10.1038/jcbfm.2011.196] [Citation(s) in RCA: 300] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 10/18/2011] [Accepted: 11/13/2011] [Indexed: 01/09/2023]
Abstract
The cerebral vascular system services the constant demand for energy during neuronal activity in the brain. Attempts to delineate the logic of neurovascular coupling have been greatly aided by the advent of two-photon laser scanning microscopy to image both blood flow and the activity of individual cells below the surface of the brain. Here we provide a technical guide to imaging cerebral blood flow in rodents. We describe in detail the surgical procedures required to generate cranial windows for optical access to the cortex of both rats and mice and the use of two-photon microscopy to accurately measure blood flow in individual cortical vessels concurrent with local cellular activity. We further provide examples on how these techniques can be applied to the study of local blood flow regulation and vascular pathologies such as small-scale stroke.
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Santisakultarm TP, Cornelius NR, Nishimura N, Schafer AI, Silver RT, Doerschuk PC, Olbricht WL, Schaffer CB. In vivo two-photon excited fluorescence microscopy reveals cardiac- and respiration-dependent pulsatile blood flow in cortical blood vessels in mice. Am J Physiol Heart Circ Physiol 2012; 302:H1367-77. [PMID: 22268102 DOI: 10.1152/ajpheart.00417.2011] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Subtle alterations in cerebral blood flow can impact the health and function of brain cells and are linked to cognitive decline and dementia. To understand hemodynamics in the three-dimensional vascular network of the cerebral cortex, we applied two-photon excited fluorescence microscopy to measure the motion of red blood cells (RBCs) in individual microvessels throughout the vascular hierarchy in anesthetized mice. To resolve heartbeat- and respiration-dependent flow dynamics, we simultaneously recorded the electrocardiogram and respiratory waveform. We found that centerline RBC speed decreased with decreasing vessel diameter in arterioles, slowed further through the capillary bed, and then increased with increasing vessel diameter in venules. RBC flow was pulsatile in nearly all cortical vessels, including capillaries and venules. Heartbeat-induced speed modulation decreased through the vascular network, while the delay between heartbeat and the time of maximum speed increased. Capillary tube hematocrit was 0.21 and did not vary with centerline RBC speed or topological position. Spatial RBC flow profiles in surface vessels were blunted compared with a parabola and could be measured at vascular junctions. Finally, we observed a transient decrease in RBC speed in surface vessels before inspiration. In conclusion, we developed an approach to study detailed characteristics of RBC flow in the three-dimensional cortical vasculature, including quantification of fluctuations in centerline RBC speed due to cardiac and respiratory rhythms and flow profile measurements. These methods and the quantitative data on basal cerebral hemodynamics open the door to studies of the normal and diseased-state cerebral microcirculation.
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Nguyen J, Ferdman J, Zhao M, Huland D, Saqqa S, Ma J, Nishimura N, Schwartz TH, Schaffer CB. Sub-surface, micrometer-scale incisions produced in rodent cortex using tightly-focused femtosecond laser pulses. Lasers Surg Med 2012; 43:382-91. [PMID: 21674543 DOI: 10.1002/lsm.21054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVE Techniques that allow targeted, micrometer-scale disruption in the depths of biological tissue, without affecting overlying structures or causing significant collateral damage, could potentially lead to new surgical procedures. We describe an optical technique to make sub-surface incisions in in vivo rodent brain and characterize the relationship between the cut width and maximum depth of these optical transections as a function of laser energy. MATERIALS AND METHODS To produce cuts, high intensity, femtosecond laser pulses were tightly focused into and translated within the cortex, through a craniotomy, in anesthetized rodents. Imaging of stained brain slices was used to characterize cut width and maximum cutting depth. RESULTS Cut width decreased exponentially as a function of depth and increased as the cube root of laser energy, but showed about 50% variation at fixed depth and laser energy. For example, at a laser energy of 13 µJ, cut width decreased from 158 ± 43.1 µm (mean ± standard deviation) to 56 ± 33 µm over depths of approximately 200-800 µm, respectively. Maximal cut depth increased logarithmically with laser energy, with cut depths of up to 1 mm achieved with 13 µJ pulses. We further showcased this technique by selectively cutting sub-surface cortical dendrites in a live, anesthetized transgenic mouse. CONCLUSIONS Femtosecond laser pulses provide the novel capacity for precise, sub-surface, cellular-scale cuts for surgical applications in optically scattering tissues.
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Nishimura N, Murase K, Ito T, Watanabe T. Ultrasonic detection of spall damage nucleation under low-velocity repeated impact. EPJ WEB OF CONFERENCES 2012. [DOI: 10.1051/epjconf/20122601046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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100
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Huynh J, Nishimura N, Rana K, Peloquin JM, Califano JP, Montague CR, King MR, Schaffer CB, Reinhart-King CA. Age-related intimal stiffening enhances endothelial permeability and leukocyte transmigration. Sci Transl Med 2011; 3:112ra122. [PMID: 22158860 PMCID: PMC3693751 DOI: 10.1126/scitranslmed.3002761] [Citation(s) in RCA: 277] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Age is the most significant risk factor for atherosclerosis; however, the link between age and atherosclerosis is poorly understood. During both aging and atherosclerosis progression, the blood vessel wall stiffens owing to alterations in the extracellular matrix. Using in vitro and ex vivo models of vessel wall stiffness and aging, we show that stiffening of extracellular matrix within the intima promotes endothelial cell permeability--a hallmark of atherogenesis. When cultured on hydrogels fabricated to match the elasticity of young and aging intima, endothelial monolayers exhibit increased permeability and disrupted cell-cell junctions on stiffer matrices. In parallel experiments, we showed a corresponding increase in cell-cell junction width with age in ex vivo aortas from young (10 weeks) and old (21 to 25 months) healthy mice. To investigate the mechanism by which matrix stiffening alters monolayer integrity, we found that cell contractility increases with increased matrix stiffness, mechanically destabilizing cell-cell junctions. This increase in endothelial permeability results in increased leukocyte extravasation, which is a critical step in atherosclerotic plaque formation. Mild inhibition of Rho-dependent cell contractility using Y-27632, an inhibitor of Rho-associated kinase, or small interfering RNA restored monolayer integrity in vitro and in vivo. Our results suggest that extracellular matrix stiffening alone, which occurs during aging, can lead to endothelial monolayer disruption and atherosclerosis pathogenesis. Because previous therapeutics designed to decrease vascular stiffness have been met with limited success, our findings could be the basis for the design of therapeutics that target the Rho-dependent cellular contractile response to matrix stiffening, rather than stiffness itself, to more effectively prevent atherosclerosis progression.
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