1
|
Stapels CJ, Kolodziejski NJ, McAdams D, Podolsky MJ, Fernandez DE, Farkas D, Christian JF. A scalable correlator for multichannel diffuse correlation spectroscopy. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9698. [PMID: 29129951 DOI: 10.1117/12.2213114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Diffuse correlation spectroscopy (DCS) is a technique which enables powerful and robust non-invasive optical studies of tissue micro-circulation and vascular blood flow. The technique amounts to autocorrelation analysis of coherent photons after their migration through moving scatterers and subsequent collection by single-mode optical fibers. A primary cost driver of DCS instruments are the commercial hardware-based correlators, limiting the proliferation of multi-channel instruments for validation of perfusion analysis as a clinical diagnostic metric. We present the development of a low-cost scalable correlator enabled by microchip-based time-tagging, and a software-based multi-tau data analysis method. We will discuss the capabilities of the instrument as well as the implementation and validation of 2- and 8-channel systems built for live animal and pre-clinical settings.
Collapse
Affiliation(s)
| | | | | | | | | | - Dana Farkas
- Radiation Monitoring Devices, Inc. 44 Hunt St (USA)
| | | |
Collapse
|
2
|
He D, Nguyen HC, Hayes-Gill BR, Zhu Y, Crowe JA, Gill C, Clough GF, Morgan SP. Laser doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing. SENSORS 2013; 13:12632-47. [PMID: 24051525 PMCID: PMC3821350 DOI: 10.3390/s130912632] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 11/16/2022]
Abstract
The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue.
Collapse
Affiliation(s)
- Diwei He
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
| | - Hoang C. Nguyen
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
| | - Barrie R. Hayes-Gill
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
| | - Yiqun Zhu
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
| | - John A. Crowe
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
| | - Cally Gill
- School of Medicine, University of Southampton, University Road, Southampton SO17 1BJ, UK; E-Mails: (C.G.); (G.F.C.)
| | - Geraldine F. Clough
- School of Medicine, University of Southampton, University Road, Southampton SO17 1BJ, UK; E-Mails: (C.G.); (G.F.C.)
| | - Stephen P. Morgan
- Electrical Systems and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK; E-Mails: (D.H.); (H.C.N.); (B.R.H.-G.); (Y.Z.); (J.A.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-115-9515-570; Fax: +44-115-9515-616
| |
Collapse
|
3
|
Tei R, Kaido T, Nakase H, Sakaki T. Secondary spinal cord hypoperfusion of circumscribed areas after injury in rats. Neurol Res 2013; 27:403-8. [PMID: 15949238 DOI: 10.1179/016164105x25180] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES The evaluation of the spatial spread of ischemia following spinal cord injury (SCI) is important for planning therapeutic strategies for secondary injury. The purpose of this study was to investigate in detail the change in regional spinal cord blood flow (rSCBF) after SCI. METHODS Thirty-four male Wistar rats were used, for which laminectomies of the T11-13 vertebrae were performed. SCI was produced by a directed impact through a laminectomy site at the level of the Th12 using a pneumatic impact device. We measured the sequential and spatial changes of rSCBF using a laser Doppler scanning technique before and after SCI in rats not only at the injured myelomere but also at the circumferent myelomeres. SCBF mapping was carried out before and after SCI on each site. RESULTS After SCI, the rSCBF value gradually decreased for each site for the SCI group (n=26), while it globally decreased at the epicenter. Moreover, a decrease in SCBF was observed at the caudal and rostral sites. The mean value of the %SCBF 120 minutes after SCI for each site was 63.6+/-2.3% (Th11), 74.4+/-4.5% (Th12), 75.8+/-3.2% (Th13), and was significantly lower for the rostral site compared with the caudal site (p<0.05, one-way analysis of variance). DISCUSSION This study found that SCBF is significantly decreased not only at the injured myelomere but also at the circumferent myelomeres. Circumferentially extending ischemia after SCI is related to secondary injury after SCI. The improvement in SCBF after SCI, therefore, can be attributed to the treatment of SCI.
Collapse
Affiliation(s)
- Rinsei Tei
- Department of Neurosurgery, Nara Medical University, Nara, Japan
| | | | | | | |
Collapse
|
4
|
Inui T, Alessandri B, Heimann A, Nishimura F, Frauenknecht K, Sommer C, Kempski O. Neuroprotective effect of ceftriaxone on the penumbra in a rat venous ischemia model. Neuroscience 2013; 242:1-10. [PMID: 23523747 DOI: 10.1016/j.neuroscience.2013.03.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 03/07/2013] [Accepted: 03/07/2013] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Glutamate transporter-1 (GLT-1) maintains low concentrations of extracellular glutamate by removing glutamate from the extracellular space. It is controversial, however, whether upregulation of GLT-1 is neuroprotective under all ischemic/hypoxic conditions. Recently, a neuroprotective effect of preconditioning with a β-lactam antibiotic ceftriaxone (CTX) that increases expression of GLT-1 has been reported in animal models of focal ischemia. On the other hand, it is said that CTX does not play a neuroprotective role in an in vitro study. Thus, we examined the effect of CTX on ischemic injury in a rat model of two-vein occlusion (2VO). This model mimics venous ischemia during, e.g. tumor surgery, a clinical situation that is best suitable for pretreatment with CTX. METHODS CTX (100mg/kg, 200mg/kg per day) or vehicle (0.9% NaCl) was intraperitoneally injected into Wistar rats for 5days before venous ischemia (n=57). Then, animals were prepared for occlusion of two adjacent cortical veins (2VO) by photothrombosis with rose bengal that was followed by KCl-induced cortical spreading depression (CSD). Infarct volume was evaluated with hematoxylin and eosin (H&E) staining 2days after venous occlusion. [(3)H]MK-801, [(3)H]AMPA and [(3)H]Muscimol ligand binding were examined autoradiographically in additional two groups without 2VO (n=5/group). Animals were injected either with NaCl (vehicle) or CTX 200mg/kg for 5days in order to evaluate whether NMDA, AMPA and GABAA ligand binding densities were affected. RESULTS CTX pretreatment reduced infarct volume compared to vehicle pretreatment (p<0.05). The effect of CTX pretreatment was attenuated by administration of the GLT-1 inhibitor, dihydrokainate (DHK) 30min before 2VO. CTX had no effect on the number of spontaneous spreading depressions after 2VO. Analysis of quantitative receptor autoradiography showed no statistically significant difference between rats after administration with CTX compared to control rats. CONCLUSIONS Pretreatment with CTX has neuroprotective potential without effect on NMDA, AMPA and GABAA receptor density and spontaneous spreading depression. This effect can be abolished by GLT-1 inhibition, indicating that upregulation of GLT-1 is an important mechanism for neuroprotective action in penumbra-like conditions, e.g. if neurosurgeons plan to occlude cerebral veins during tumor surgery.
Collapse
Affiliation(s)
- T Inui
- Institute for Neurosurgical Pathophysiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz 55131, Germany
| | | | | | | | | | | | | |
Collapse
|
5
|
He D, Nguyen HC, Hayes-Gill BR, Zhu Y, Crowe JA, Clough GF, Gill CA, Morgan SP. 64×64 pixel smart sensor array for laser Doppler blood flow imaging. OPTICS LETTERS 2012; 37:3060-3062. [PMID: 22859085 DOI: 10.1364/ol.37.003060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
What is believed to be the first fully integrated two-dimensional complementary metal oxide semiconductor (CMOS) imaging array for laser Doppler blood flow imaging is demonstrated. The sensor has 64×64 pixels and includes both analog and digital on-chip processing electronics. This offers several potential advantages over commercial sensors as the processing is tailored to the signals of interest and the data bottleneck that exists between the sensor and processing electronics is overcome. To obtain a space efficient design over 64×64 pixels means that standard processing electronics used off-chip cannot be implemented. Images of both simulated blood flow responses and a blood flow occlusion test demonstrate the capability.
Collapse
Affiliation(s)
- D He
- Faculty of Engineering, University of Nottingham, University Park, Nottingham, UK
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Miki K, Ishibashi S, Sun L, Xu H, Ohashi W, Kuroiwa T, Mizusawa H. Intensity of chronic cerebral hypoperfusion determines white/gray matter injury and cognitive/motor dysfunction in mice. J Neurosci Res 2009; 87:1270-81. [PMID: 18951530 DOI: 10.1002/jnr.21925] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We sought to establish a mouse model of subcortical ischemic vascular dementia (SIVD) that develops predominant white matter (WM) injury and cognitive dysfunction induced by chronic cerebral hypoperfusion. Adult C57Bl/6 male (n = 48) mice were subjected to bilateral common carotid artery stenosis with external microcoils (inner diameters: 0.16 mm, left; 0.18 mm, right). Mice were categorized according to left-side cerebral blood flow (CBF) value on day 6 into those with severe cerebral hypoperfusion (SCH; n = 16, < 30% of preoperative CBF baseline value) or moderate cerebral hypoperfusion (MCH; n = 21, 30-50% of preoperative value). Another 15 mice were sham operated. Neurological dysfunction was evaluated by Morris water maze, rotating rod, and open field tests. Histopathological examination was performed on day 35 after surgery. MCH animals showed persistent hyperlocomotion with reduced anxiety and spatial reference memory dysfunction. Rarefaction and small necrotic lesions were predominantly confined to the WM, with reactive astrocytosis, microglial infiltration, axonal loss, and myelin disruption, and these changes were dominant on the left side. SCH animals had persistent hyperlocomotion and motor dysfunction, and their ischemic lesions extended from the WM to the hippocampus and cortex. In MCH animals, myelin basic protein and neurofilament fiber densities in the WM were correlated with the time spent in the correct area in the water maze probe trials. Our MCH mouse model with the development of several types of neurological dysfunction with high reproducibility would be useful for investigating the pathomechanisms of WM injury in human SIVD.
Collapse
Affiliation(s)
- Kazunori Miki
- Department of Neurology and Neurological Science, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | | | | | | | | | | | | |
Collapse
|
7
|
Rossow M, Mantulin WW, Gratton E. Spatiotemporal image correlation spectroscopy measurements of flow demonstrated in microfluidic channels. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:024014. [PMID: 19405744 PMCID: PMC2702990 DOI: 10.1117/1.3088203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Accurate blood flow measurements during surgery can improve an operation's chance of success. We developed near-infrared spatio-temporal image spectroscopy (NIR-STICS), which has the potential to make blood flow measurements that are difficult to accomplish with existing methods. Specifically, we propose the technique and we show feasibility on phantom measurements. NIR-STICS has the potential of measuring the fluid velocity in small blood vessels (less than 1 mm in diameter) and of creating a map of blood flow rates over an area of approximately 1 cm(2). NIR-STICS employs near-infrared spectroscopy to probe inside blood vessel walls and spatiotemporal image correlation spectroscopy to directly-without the use of a model-extract fluid velocity from the fluctuations within an image. We present computer simulations and experiments on a phantom system that demonstrate the effectiveness of NIR-STICS.
Collapse
Affiliation(s)
- Molly Rossow
- University of California Irvine, Biomedical Engineering Department, 3120 Natural Sciences 2, Irvine, CA 92697-2715, Phone: 949-824-3264, Fax: 949-824-1727,
| | - William W. Mantulin
- University of California Irvine, Beckman Laser Institute, 1002 Health Sciences Rd, Irvine, CA 92612, Phone: 949-824-8859, Fax: 949-824-1727,
| | - Enrico Gratton
- University of California Irvine, Biomedical Engineering Department, 3120 Natural Sciences 2, Irvine, CA 92697-2715, Phone: 949-824-2674, Fax: 949-824-1727,
| |
Collapse
|
8
|
Suzuki M, Funabiki T, Hori S, Aikawa N. Spontaneous gasping increases cerebral blood flow during untreated fatal hemorrhagic shock. Resuscitation 2009; 80:109-12. [DOI: 10.1016/j.resuscitation.2008.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 08/06/2008] [Accepted: 08/20/2008] [Indexed: 11/16/2022]
|
9
|
Nobuoka T, Mizuguchi T, Oshima H, Shibata T, Kimura Y, Mitaka T, Katsuramaki T, Hirata K. Portal blood flow regulates volume recovery of the rat liver after partial hepatectomy: molecular evaluation. Eur Surg Res 2006; 38:522-32. [PMID: 17047332 DOI: 10.1159/000096292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 08/02/2006] [Indexed: 12/13/2022]
Abstract
BACKGROUND/AIM Liver regeneration is a finely tuned process that is closely regulated by multiple cell cycle steps. Although the portal blood flow affects liver regeneration, the molecular mechanism by which the blood flow regulates gene expression and liver function is largely unknown. The aim of this study was to investigate the molecular effect of portal blood flow on hepatocyte proliferation and gene regulation during liver regeneration. MATERIALS AND METHODS We developed a simple surgical rat model to investigate the relation between portal blood flow and liver regeneration by partially ligating the portal trunk with 8-0 Proline sutures under microscopy to reduce the blood flow by 40%. We investigated recovery of liver volume, DNA synthesis, and gene expression associated with cell cycle regulators, comparing partially hepatectomized (PH) rats without (PH group; n = 30) and with partial portal ligation (PHPL group; n = 30) for 7 days after the operation. RESULTS The hepatic tissue blood flow and the recovery ratio between liver weight and body weight in the PHPL group were significantly lower than in the PH group after hepatectomy. The peak 5-bromo-2'-deoxyuridine labeling index in the PHPL group was delayed and weak compared with the PH group. The expression of CT-1 and cyclin D, E, and B mRNAs indicated that the liver regeneration in the PHPL group was delayed and weak. In addition, there was reciprocal expression of C/EBPalpha and C/EBPbeta mRNAs, an observation supported by their nuclear protein levels. Furthermore, the cytochrome P-450 protein level in the PHPL group was higher than that in the PH group 1 day after hepatectomy. CONCLUSION The portal blood flow regulates the activity of liver regeneration and the gene expression associated with cell cycle regulators, while the functions are maintained.
Collapse
Affiliation(s)
- T Nobuoka
- Department of Surgery I, Sapporo Medical University Hospital, Sapporo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Nakagawa I, Alessandri B, Heimann A, Kempski O. MitoKATP-Channel Opener Protects against Neuronal Death in Rat Venous Ischemia. Neurosurgery 2005; 57:334-40; discussion 334-40. [PMID: 16094164 DOI: 10.1227/01.neu.0000166681.88736.86] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Mitochondrial adenosine triphosphate-dependent potassium (mitoKATP) channels are present in the brain, and several reports have shown their neuroprotective, preconditioning effect against an ischemic insult. The role of mitoKATP channels in the penumbra area has not been studied thoroughly. In a model of venous ischemia, widespread penumbra-like low flow areas are created, which are susceptible to cortical spreading depression. Thus, we studied effects of mitoKATP channels on infarct size in this model. METHODS Male Wistar rats were subjected to two-vein occlusion by photochemical thrombosis of two adjacent cortical veins combined with KCl-induced cortical spreading depression. The rats were assigned to four experimental groups pretreated intraventricularly 15 minutes before two-vein occlusion with 1) vehicle, 2) the mitoKATP channel opener diazoxide (2 mmol/L), 3) diazoxide (2 mmol/L) plus the selective mitoKATP channel blocker 5-hydroxydecanoate (5-HD; 100 mmol/L), or 4) 5-HD alone (100 mmol/L). Regional cerebral blood flow (laser Doppler scanning) and brain cell swelling (impedance) were monitored acutely. Infarct volume was assessed 7 days after ischemia. RESULTS Pretreatment with diazoxide significantly reduced the infarct volume from 6.2 +/- 0.7 mm3 to 3.8 +/- 0.4 mm3, whereas regional cerebral blood flow in the vicinity of the two veins was comparable in both groups 70 minutes after two-vein occlusion. Effects of diazoxide were abolished by 5-HD, whereas 5-HD alone even increased infarct volume. CONCLUSION These results suggest that the opening of mitoKATP channels plays a major role in brain protection under penumbra-like conditions, as shown in this venous occlusion model.
Collapse
Affiliation(s)
- Ichiro Nakagawa
- Institute for Neurosurgical Pathophysiology, Johannes Gutenberg University, Mainz, Germany
| | | | | | | |
Collapse
|
11
|
Rubertsson S, Karlsten R. Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation. Resuscitation 2005; 65:357-63. [PMID: 15919574 DOI: 10.1016/j.resuscitation.2004.12.006] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2004] [Revised: 11/19/2004] [Accepted: 12/09/2004] [Indexed: 12/12/2022]
Abstract
OBJECTIVE LUCAS is a new device for mechanical compression and decompression of the chest during cardiopulmonary resuscitation (CPR). The aim of this study was to compare the efficacy of this new device with standard manual external chest compressions using cerebral cortical blood flow, cerebral oxygen extraction, and end-tidal CO2 for indirect measurement of cardiac output. Drug therapy, with adrenaline (epinephrine) was eliminated in order to evaluate the effects of chest compressions alone. METHODS Ventricular fibrillation (VF) was induced in 14 anaesthetized pigs. After 8 min non-intervention interval, the animals were randomized into two groups. One group received external chest compressions using a new mechanical device, LUCAS. The other group received standard manual external chest compressions. The compression rate was 100 min(-1) and mechanical ventilation was resumed with 100% oxygen during CPR in both groups. No adrenaline was given. After 15 min of CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. End-tidal CO2 was measured using mainstream capnography. RESULTS During CPR, the cortical cerebral blood flow was significantly higher in the group treated with LUCAS (p = 0.041). There was no difference in oxygen extraction between the groups. End-tidal CO2, an indirect measurement of the achieved cardiac output during CPR, was significantly higher in the group treated with the LUCAS device (p = 0.009). Restoration of spontaneous circulation was achieved in two animals, one from each group. CONCLUSIONS Chest compressions with the LUCAS device during experimental cardiopulmonary resuscitation resulted in higher cerebral blood flow and cardiac output than standard manual external chest compressions. These results strongly support prospective randomised studies in patients to evaluate this new device.
Collapse
Affiliation(s)
- Sten Rubertsson
- Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University Hospital, S-75185 Uppsala, Sweden.
| | | |
Collapse
|
12
|
Burger R, Bendszus M, Vince GH, Solymosi L, Roosen K. Neurophysiological monitoring, magnetic resonance imaging, and histological assays confirm the beneficial effects of moderate hypothermia after epidural focal mass lesion development in rodents. Neurosurgery 2004; 54:701-11; discussion 711-2. [PMID: 15028147 DOI: 10.1227/01.neu.0000108784.80585.ee] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2003] [Accepted: 11/06/2003] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To assess the effects of moderate intraischemic hypothermia on neurophysiological parameters in an epidural balloon compression model in rats and to correlate the results with magnetic resonance imaging and histological findings. METHODS Neurophysiological monitoring included laser Doppler flow, tissue partial oxygen pressure, and intracranial pressure measurements and electroencephalographic assessments during balloon expansion, sustained inflation, and reperfusion. Moderate intraischemic cooling of animals was extended throughout the reperfusion period, and results were compared with those for normothermic animals. Moreover, histological morphometric and magnetic resonance imaging volumetric analyses of the lesions were performed. RESULTS Laser Doppler flow decreased slightly during ischemia (P < 0.05) in animals treated with hypothermia, and flow values demonstrated complete reperfusion, compared with incomplete flow restoration in untreated animals (P < 0.05). During ischemia, the tissue partial oxygen pressure was less than 4.3 mm Hg in both groups. After reperfusion, values returned to the normal range in both groups, but the tissue partial oxygen pressure in hypothermic animals was significantly higher (P = 0.042) and demonstrated 19% higher values, compared with normothermic animals, before rewarming. Moderate hypothermia attenuated a secondary increase in intracranial pressure (P < 0.05), and electroencephalographic findings indicated a trend toward faster recovery (P > 0.05) after reperfusion. Lesion size was reduced by 35% in magnetic resonance imaging volumetric evaluations and by 24.5% in histological morphometric analyses. CONCLUSION Intraischemic hypothermia improves cerebral microcirculation, attenuates a secondary increase in intracranial pressure, facilitates electroencephalographic recovery, and reduces the lesion size.
Collapse
Affiliation(s)
- Ralf Burger
- Department of Neurosurgery, University of Regensburg, Regensburg, Germany.
| | | | | | | | | |
Collapse
|
13
|
Burger R, Bendszus M, Vince GH, Roosen K, Marmarou A. A new reproducible model of an epidural mass lesion in rodents. Part I: Characterization by neurophysiological monitoring, magnetic resonance imaging, and histopathological analysis. J Neurosurg 2002; 97:1410-8. [PMID: 12507141 DOI: 10.3171/jns.2002.97.6.1410] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The goal of this study was to characterize a new model of an epidural mass lesion in rodents by means of neurophysiological monitoring, magnetic resonance imaging, and histopathological analysis. METHODS Changes in intracranial pressure (ICP), cerebral perfusion pressure (CPP), and laser Doppler flowmetry (LDF) values, intraparenchymal tissue partial oxygen pressure (PtiO2), and electroencephalography (EEG) activity were evaluated in the rat during controlled, epidural expansion of a latex balloon up to a maximum ICP of 60 mm Hg. The initial balloon inflation was followed by periods of sustained inflation (30 +/- 1 minute) and reperfusion (180 +/- 5 minutes). Histopathological analysis and magnetic resonance (MR) imaging were performed to characterize the lesion. The time to maximum balloon expansion and the average balloon volume were highly reproducible. Alterations in EEG activity during inflation first appeared when the CPP decreased to 57 mm Hg, the LDF value to 66% of baseline values. and the PtiO2 to 12 mm Hg. During maximum compression, the CPP was reduced to 34 mm Hg, the LDF value to 40% of baseline, and the PtiO2 to 4 to 5 mm Hg. The EEG tracing was isoelectric during prolonged inflation and the values of LDF and PtiO2 decreased due to accompanying hypotonia. After reperfusion, the CPP was significantly decreased (p < 0.05) due to the elevation of ICP. Both the LDF value and EEG activity displayed incomplete restoration, whereas the value of PtiO2 returned to normal. Histological analysis and MR imaging revealed brain swelling with a midline shift and a combined cortical-subcortical ischemic lesion beyond the site of balloon compression. CONCLUSIONS This novel model of an epidural mass lesion in rodents closely resembles the process observed in humans. Evaluation of pathophysiological and morphological changes was feasible by using neurophysiological monitoring and MR imaging.
Collapse
Affiliation(s)
- Ralf Burger
- Department of Neurosurgery, University of Würzburg, Germany.
| | | | | | | | | |
Collapse
|
14
|
Steinmeier R, Bondar I, Bauhuf C, Fahlbusch R. Laser Doppler flowmetry mapping of cerebrocortical microflow: characteristics and limitations. Neuroimage 2002; 15:107-19. [PMID: 11771979 DOI: 10.1006/nimg.2001.0943] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to quantitatively analyze the amount of methodological noise and the spatial and temporal variability of laser Doppler flowmetry (LDF) signals mapping cerebrocortical microflow. In an experimental setup with latex beads, the methodological LDF-signal variability was determined (coefficient of variation or CV(method)). The biological variability of the LDF signals was measured in animal experiments using 10 anesthetized rabbits. One stationary reference probe was used to assess temporal heterogeneity (CV(temp)) and a micromanipulator-driven scanning probe was used to assess spatial heterogeneity (CV(spat)) in a cortical area of 3.5 x 4.5 mm with 252 measurement points. CO(2) tests were used to modulate cerebrovascular resistance. CV(method) was found to be 4.94 +/- 1.7. The CV(temp) for the LDF-velocity signal was assessed to be 13.93 +/- 5.9 during normocapnia. Scanning of the brain surface with the scanning probe revealed a CV(spat) for LDF velocity of 65.0 +/- 16.2 during normocapnia. CO(2) modulation (hypocapnia --> normocapnia --> hypercapnia) of the cerebral resistance did not show a significant change in temporal heterogeneity (10.84 +/- 3.1 --> 13.93 +/- 5.9 --> 14.82 +/- 3.9), whereas spatial heterogeneity decreased significantly (81.31 +/- 12.0 --> 65.0 +/- 16.2 --> 54.04 +/- 21.8). Although the spatial and temporal variability of LDF signals evoked by cerebrocortical microflow is in the same range as with other methods and in other organs, LDF cerebrocortical mapping is restricted by the large temporal and spatial heterogeneity of the cerebrocortical vasculature. The definitions of sample volume, scanning step width, probe to brain surface distance, and average time per scanning point are critical concerning reliable LDF cerebrocortical mapping techniques.
Collapse
Affiliation(s)
- Ralf Steinmeier
- Department of Neurosurgery, University of Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | | | | | | |
Collapse
|
15
|
Nakase H, Kaido T, Okuno S, Hoshida T, Sakaki T. Novel intraoperative cerebral blood flow monitoring by laser-Doppler scanner. Neurol Med Chir (Tokyo) 2002; 42:1-4. [PMID: 11902070 DOI: 10.2176/nmc.42.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Laser-Doppler (LD) flowmetry was used to measure tissue perfusion non-invasively and continuously during neurosurgical operations using an LD scanner. Scanning was usually completed in 20 seconds. Measurements were processed in software to provide a color-coded image of the tissue perfusion. Moreover, the measurement data, expressed in LD-units, could be used for statistical data analysis. No physical contact was necessary between the scanning device and the exposed brain tissue. The imager provided two-dimensional microvascular flow maps non-invasively and quantitatively during brain operations, and could show the CO2 reactivity in the vessels. LD scanning flowmetry is a promising intraoperative monitoring method for cerebral blood flow changes.
Collapse
Affiliation(s)
- Hiroyuki Nakase
- Department of Neurosurgery, Nara Medical University, Kashihara, Nara.
| | | | | | | | | |
Collapse
|
16
|
Nakase H, Sakaki T, Kempski O. A scanning technique to measure regional cerebral blood flow and oxyhemoglobin level. Neurosurgery 2001; 48:1335-42; discussion 1342-3. [PMID: 11383738 DOI: 10.1097/00006123-200106000-00032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE The application of a laser scanning technique to measure regional cerebral blood flow (CBF) and tissue hemoglobin oxygenation (HbO2) using the rat closed cranial window preparation is described. METHODS Twenty-nine male Wistar rats were used to consecutively measure local CBF by laser Doppler flowmetry and tissue HbO2 by a microspectrophotometric method at multiple corresponding cortical locations. The scanning technique used a computer-controlled micromanipulator. Data from three experimental models are presented: the whisker stimulation model, the ischemia-reperfusion model, and the sinus-vein thrombosis model. Sequential changes in local CBF and HbO2 data before, during, and after stimulation, ischemia, and sinus thrombosis were examined. Data from predefined locations within the same region were correlated with the topographical location and then arranged in a three-dimensional image. RESULTS In the whisker stimulation model, we found a disproportionate increase in CBF (32 +/- 12%) as compared with that of HbO2 (9 +/- 4%) during stimulation. In the ischemia-reperfusion model, the three-dimensional image showed heterogeneous low CBF (depending on the area) and homogeneous HbO2 at a reduced level during ischemia and postischemic hyperperfusion. However, the range of oxygenation was normal after reperfusion. In the sinus-vein thrombosis model, drainage of the unsaturated blood via the collateral pathways was noted. CONCLUSION The laser scanning technique is useful for visualizing sequential changes in hemodynamic-metabolic interactions of cortical brain tissue. This technique can reveal phenomena not detected by traditional monitoring procedures.
Collapse
Affiliation(s)
- H Nakase
- Department of Neurosurgery, Nara Medical University, Japan.
| | | | | |
Collapse
|
17
|
Nakase H, Sakaki T, Kempski O. A Scanning Technique to Measure Regional Cerebral Blood Flow and Oxyhemoglobin Level. Neurosurgery 2001. [DOI: 10.1227/00006123-200106000-00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
18
|
Otsuka H, Nakase H, Nagata K, Ueda K, Kempski O, Sakaki T. Effect of age on cerebral venous circulation disturbances in the rat. J Neurosurg 2000; 93:298-304. [PMID: 10930017 DOI: 10.3171/jns.2000.93.2.0298] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Mild cerebral venous circulation disturbances (CVCDs) in aged patients are frequently known to cause unexpectedly severe postoperative complications in neurosurgical practice. The object of the present study was to determine whether there are age-related differences involved in vulnerability to CVCDs. METHODS Thirty-eight male Wistar rats were used. A single cortical vein with a 100-microm diameter was occluded photochemically by using rose bengal dye and fiberoptic illumination in young (Group Y, 19 animals aged 10-14 weeks) and aged (Group A, seven animals aged 80-100 weeks) rats. Five young and seven aged animals served as sham-operated controls. Regional cerebral blood flow (rCBF) was determined from local CBF, which was measured at 25 (5 x 5) identical locations, with the occluded vein located central to the scanning field, by using a laser Doppler scanning technique every 15 minutes for 90 minutes after venous occlusion. The cerebral venous flow pattern was examined using fluorescence angiography until 90 minutes after occlusion. Histological specimens were examined 24 hours after occlusion. In Group Y, rCBF did not change significantly after venous occlusion. However, in Group A, rCBF decreased rapidly beginning 15 minutes after occlusion. Significant intergroup differences were observed 30, 60, and 90 minutes after occlusion. Venous flow arrest, which resulted in venous infarct, was observed on angiography 90 minutes after occlusion in two (10.5%) of 19 young and six (85.7%) of seven aged rats. The venous thrombus in Group A rats was significantly larger than that in Group Y rats 90 minutes after occlusion. Venous infarction was seen in all aged rats (100%) and in six young rats (31.6%); the infarct size, expressed as a percentage of the size of the ipsilateral hemisphere, was significantly larger in aged rats than in young rats. CONCLUSIONS This study demonstrated an age-related increase in the rate and size of venous infarct following vein occlusion, suggesting that the greater vulnerability to CVCDs in the aged brain might be attributed to early and extensive hypoperfusion of circumscribed brain areas drained by the occluded vein. The larger thrombus formation in aged animals indicates that a shift in the thrombogenetic/thrombolytic equilibrium is responsible for the observed effect.
Collapse
Affiliation(s)
- H Otsuka
- Department of Neurosurgery, Nara Medical University, Kashihara City, Japan
| | | | | | | | | | | |
Collapse
|
19
|
Otsuka H, Ueda K, Heimann A, Kempski O. Effects of cortical spreading depression on cortical blood flow, impedance, DC potential, and infarct size in a rat venous infarct model. Exp Neurol 2000; 162:201-14. [PMID: 10716901 DOI: 10.1006/exnr.1999.7326] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. In 36 rats local CBF, DC potential, and brain tissue impedance were measured continuously for 75 min after vein occlusion. No, 3, or 10 CSD waves were induced by potassium chloride injection during the initial 75 min. Rats were compared for spontaneous CSDs; baseline local CBF, CBF, and impedance response to CSD; and infarct volume. Seventy-five minutes after vein occlusion regional cortical flow in a 3.5x7-mm window was reduced to 34.3+/-13.2%. At 45% of the 840 measured locations in 7 rats flow was <40% baseline and at 27.3% <30%, indicating a widespread penumbra territory. During the initial 75 min 2.1+/-1.1 spontaneous CSDs were observed. There was a positive correlation between the number of spontaneous CSDs seen acutely and infarction volume after 5 days. Moreover, brain injury was significantly increased in the group with 10 KCl-induced CSDs. A reduced 1CBF response and an overshooting tissue impedance change during CSD were predictors of ischemic damage. This study demonstrates a CSD-related growth of the venous infarct. Second, the data indicate that flow after two-vein occlusion resembles that seen under penumbra conditions, allowing for studies of damage mechanisms responsible for infarct growth.
Collapse
Affiliation(s)
- H Otsuka
- Institute for Neurosurgical Pathophysiology, Johannes Gutenberg University, Mainz, 55101, Germany
| | | | | | | |
Collapse
|