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Rizzoni D, Mengozzi A, Masi S, Agabiti Rosei C, De Ciuceis C, Virdis A. New Noninvasive Methods to Evaluate Microvascular Structure and Function. Hypertension 2022; 79:874-886. [PMID: 35114816 DOI: 10.1161/hypertensionaha.121.17954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The structural and functional alterations of microvessels are detected because of physiological aging and in several cardiometabolic diseases, including hypertension, diabetes, and obesity. The small resistance arteries of these patients show an increase in the media or total wall thickness to internal lumen diameter ratio (MLR or WLR), often accompanied by endothelial dysfunction. For decades, micromyography has been considered as a gold standard method for evaluating microvascular structural alterations through the measurement of MLR or WLR of subcutaneous small vessels dissected from tissue biopsies. Micromyography is the most common and reliable method for assessing microcirculatory endothelial function ex vivo, while strain-gauge venous plethysmography is considered the reference technique for in vivo studies. Recently, several noninvasive methods have been proposed to extend the microvasculature evaluation to a broader range of patients and clinical settings. Scanning laser Doppler flowmetry and adaptive optics are increasingly used to estimate the WLR of retinal arterioles. Microvascular endothelial function may be evaluated in the retina by flicker light stimulus, in the finger by tonometric approaches, or in the cutaneous or sublingual tissues by laser Doppler flowmetry or intravital microscopy. The main limitation of these techniques is the lack of robust evidence on their prognostic value, which currently reduces their widespread use in daily clinical practice. Ongoing and future studies will overcome this issue, hopefully moving the noninvasive assessment of the microvascular function and structure from bench to bedside.
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Affiliation(s)
- Damiano Rizzoni
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Italy (D.R., C.A., C.D.C.).,Division of Medicine, Spedali Civili di Brescia, Montichiari (Brescia), Italy (D.R.)
| | - Alessandro Mengozzi
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (A.M., S.M., A.V.).,Institute of Life Science, Sant'Anna School of Advanced Studies, Pisa, Italy (A.M.)
| | - Stefano Masi
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (A.M., S.M., A.V.).,Institute of Cardiovascular Science, University College London, United Kingdom (S.M.)
| | - Claudia Agabiti Rosei
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Italy (D.R., C.A., C.D.C.)
| | - Carolina De Ciuceis
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Italy (D.R., C.A., C.D.C.)
| | - Agostino Virdis
- Department of Clinical and Experimental Medicine, University of Pisa, Italy (A.M., S.M., A.V.)
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Kannenkeril D, Bosch A, Kolwelter J, Jung S, Striepe K, Ott C, Delles C, Schmieder RE. Dependency of flow-mediated vasodilatation from basal nitric oxide activity. Clin Physiol Funct Imaging 2021; 41:310-316. [PMID: 33621423 DOI: 10.1111/cpf.12696] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/11/2021] [Accepted: 02/16/2021] [Indexed: 01/22/2023]
Abstract
BACKGROUND Flow-mediated vasodilatation (FMD) has become one of the most widely assessed parameters to analyse endothelial and vascular function in cardiovascular medicine. The degree of contribution of nitric oxide (NO) to FMD is inconclusive and varies widely depending on the device used. In this study, we used a semi-automatic ultrasound device to analyse to what extent basal NO activity contributes to FMD of the brachial artery. METHODS FMD was assessed with the UNEX EF device in a cross-over single blinded randomized study at baseline and then during infusion of either a NO-synthase-inhibitor (NG-monomethyl-L-arginine (L-NMMA)) or saline. The analysis was repeated after 1 week with the alternative infusion of L-NMMA or saline. All measurements were analysed both automatically and by a technician manually. RESULTS In total, 25 healthy men subjects completed the study. Diastolic blood pressure and heart rate significantly changed during infusion of L-NMMA. Infusion of L-NMMA reduced FMD significantly (-37%, p = 0.002). Saline solution had no effect on FMD (+14%, p = 0.392). Change in FMD was significantly different between the groups (ΔFMDL-NMMA vs. ΔFMDsaline , p = 0.032). There was a statistically significant correlation between automatically analysed results and those obtained by an experienced technician (FMDsaline : r = 0.822, p < 0.001; FMDL-NMMA : r = 0.645, p = 0.007). CONCLUSION The influence of NO on FMD is approximately 40% if assessed using the UNEX EF. Prior to use FMD as a marker of endothelial dysfunction, we should explore different methods including various duration of forearm ischaemia to increase NO dependency of FMD.
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Affiliation(s)
- Dennis Kannenkeril
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Agnes Bosch
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Julie Kolwelter
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Department of Cardiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Susanne Jung
- Department of Cardiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Kristina Striepe
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christian Ott
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Department of Nephrology and Hypertension, Paracelsus Medical University, Nürnberg, Germany
| | - Christian Delles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Roland E Schmieder
- Department of Nephrology and Hypertension, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
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Rizzoni D, Agabiti Rosei C, De Ciuceis C, Semeraro F, Rizzoni M, Docchio F. New Methods to Study the Microcirculation. Am J Hypertens 2018; 31:265-273. [PMID: 29228086 DOI: 10.1093/ajh/hpx211] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Essential hypertension is associated with structural alterations in the microvessels; in particular, an increase in the media thickness to internal lumen ratio of small resistance arteries (MLR) and a reduction in capillary density have been observed. The evaluation of the morphological characteristics of small resistance arteries in humans is challenging. The gold-standard method is generally considered to be the measurement by wire or pressure micromyography of MLR of subcutaneous small vessels obtained by local biopsies. However, noninvasive techniques for the evaluation of retinal arterioles were recently proposed; in particular, 2 approaches, scanning laser Doppler flowmetry (SLDF) and adaptive optics (AO), seem to provide useful information. Both of them provide an estimation of the wall to lumen ratio (WLR) of retinal arterioles. Moreover, a noninvasive measurement of basal and total capillary density may be obtained by videomicroscopy/capillaroscopy. It has been recently demonstrated that AO has a substantial advantage over SLDF in terms of evaluation of microvascular morphology, since WLR measured with AO is more closely correlated with the M/L of subcutaneous small arteries. The possibility to noninvasively assess in a reliable way, microvascular morphology in a clinical setting may represent a major advancement, since micromyography has substantial limitations in its application due to the local invasiveness of the procedure.
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Affiliation(s)
- Damiano Rizzoni
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
- Istituto Clinico Città di Brescia, Division of Medicine, Brescia, Italy
| | - Claudia Agabiti Rosei
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Carolina De Ciuceis
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Francesco Semeraro
- Eye Clinic, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Marco Rizzoni
- Department of Information Engineering, University of Brescia, Brescia, Italy
| | - Franco Docchio
- Department of Mechanical and Industrial Engineering, University of Brescia, Brescia, Italy
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Significance of frailty for predicting adverse clinical outcomes in different patient groups with specific medical conditions. Z Gerontol Geriatr 2016; 49:567-572. [PMID: 27628103 DOI: 10.1007/s00391-016-1128-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/25/2016] [Accepted: 08/10/2016] [Indexed: 02/08/2023]
Abstract
Frailty is a major health burden in an aging society. It constitutes a clinical state of reduced physiological reserves that is associated with a diminished ability to withstand internal and external stressors. Frail patients have an increased risk for adverse clinical outcomes, such as mortality, readmission to hospital, institutionalization and falls. Of further clinical interest, frailty might be at least in part reversible in some patients and subject to preventive strategies. In daily clinical practice older patients with a complex health status, who are mostly frail or at least at risk of developing frailty, are frequently cared for by geriatricians. Recently, clinicians and scientists from other medical disciplines, such as cardiology, pulmonology, gastroenterology, nephrology, endocrinology, rheumatology, surgery and critical care medicine also discovered frailty to be an interesting instrument for risk stratification of patients, including younger patients. In this review we highlight the results of recent studies that demonstrated the significance of frailty to predict adverse clinical outcomes in patients with specific medical conditions, such as cardiac, lung, liver and kidney diseases as well as diabetes mellitus, osteoarthritis, trauma patients, patients undergoing surgery and critically ill patients. Multiple studies in patients with the aforementioned specific medical conditions could be identified demonstrating a predictive role of frailty for several adverse clinical outcomes. The association between frailty and adverse clinical outcomes reported in these studies was in part independent of several major potential confounder factors, such as age, sex, race, comorbidities and disabilities and were also detected in younger patients.
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Wolz J, Audebert H, Laumeier I, Ahmadi M, Steinicke M, Ferse C, Michelson G. Telemedical assessment of optic nerve head and retina in patients after recent minor stroke or TIA. Int Ophthalmol 2016; 37:39-46. [PMID: 27016938 DOI: 10.1007/s10792-016-0222-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 03/16/2016] [Indexed: 11/26/2022]
Abstract
The aim of the study is to telemedically assess the prevalence of simple optic nerve atrophy and retinal arteriolar anomalies in subjects who have had a minor stroke or TIA within 14 days, and to compare these results with an age-matched control group. By using a mobile examination unit, retinal photographs were taken with a 45° non-mydriatic colour fundus camera (KOWA NM-45, non-mydriatic-alpha) in patients who had suffered from a minor stroke or TIA within 14 days of the time of the examination. Retinal photographs were focused on the optic nerve head region. Pupils were not dilated. The documented medical history and the retinal images were stored on a server using browser independent web-based software running on PCs, tablets and smartphones. After completing the upload of the medical interview and the retinal images into the electronic patient chart, all retinal images were evaluated via telemedicine by an experienced senior consultant ophthalmologist. Age-matched normotensive, non-diabetic subjects (aged 40-89 years) who reported no systemic or ocular diseases were used as the control group. Both study groups were divided into five decades of life (40-49; 50-59; 60-69; 70-79; 80-89 years). We calculated the prevalences and the ratios of prevalences of optic nerve atrophy and retinal arteriolar anomalies between the stroke and the control group per decades of life. 139 minor stroke or TIA subjects (aged 40-89 years) and 1611 age-matched control subjects were examined. In the stroke group, we found significantly increased prevalences of optic nerve atrophy and retinal arteriolar anomalies throughout the 5th-8th decade of life when compared to age-matched controls. The prevalence of optic nerve atrophy in stroke subjects outranged the prevalence in the controls depending on age-class by a factor of 3-21. Simple optic nerve atrophy is frequent in patients who have suffered from an ischemic stroke or TIA, and it seems to indicate vascular damage, indicating the necessity for telemedically assisted assessment of the optic nerve.
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Affiliation(s)
- Johannes Wolz
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Heinrich Audebert
- Department of Neurology, Centre for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Inga Laumeier
- Department of Neurology, Centre for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Michael Ahmadi
- Department of Neurology, Centre for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Maureen Steinicke
- Department of Neurology, Centre for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Caroline Ferse
- Department of Neurology, Centre for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Georg Michelson
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Interdisciplinary Centre of Ophthalmic Preventive Medicine and Imaging, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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The influence of new beta-adrenolytics nebivolol and carvedilol on intraocular pressure and iris blood flow in rabbits. Graefes Arch Clin Exp Ophthalmol 2014; 252:917-23. [PMID: 24705852 PMCID: PMC4035558 DOI: 10.1007/s00417-014-2623-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 02/20/2014] [Accepted: 03/14/2014] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND The aim of this study was to assess the influence of propranolol, nebivolol, and carvedilol on intraocular pressure and blood flow in vessels of rabbit's (New Zealand White) eyeball. METHODS The study was carried out on New Zealand white rabbits. Intraocular pressure was measured with the applanation tonometer Möller-Wedel and Icare; blood flow was measured with Doppler Laser Blood Flow Monitor MBD3. RESULTS Following a single administration into a conjunctival sac, all drugs decreased intraocular pressure. Iris blood flow was decreased following administration of propranol, but increased by nebivolol and carvedilol. After single and repeated oral administration of nebivolol and carvedilol an IOP decrease was demonstrated, but with no effect of all applied doses on iris or retina/choroid blood flow. CONCLUSION Studies performed on an animal model indicate that it is possible to reduce the intraocular pressure and increase ocular blood flow in humans, following topical administration of carvedilol and nebivolol. Confirmation of those results in clinical trials may lead to development of a new anti-glaucoma treatment. Further clinical studies of long-term nebivolol and carvedilol are recommended. They are necessary for evaluation of usefulness of those drugs for selected groups of patients, for example those with glaucoma and arterial hypertension.
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Ott C, Raff U, Schmidt S, Kistner I, Friedrich S, Bramlage P, Harazny JM, Schmieder RE. Effects of saxagliptin on early microvascular changes in patients with type 2 diabetes. Cardiovasc Diabetol 2014; 13:19. [PMID: 24423149 PMCID: PMC3897922 DOI: 10.1186/1475-2840-13-19] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 01/11/2014] [Indexed: 01/21/2023] Open
Abstract
Background Patients with diabetes mellitus are at increased risk for microvascular complications. Early changes in microcirculation are characterized by hyperperfusion (e.g. in the retina and kidney) and increased pulse wave reflection leading to increased aortic pressure. We investigated the effects of the DPP-4-inhibitor saxagliptin on early retinal microvascular changes. Methods In this double-blind, controlled, cross-over trial 50 patients (without clinical signs of microvascular alterations) with type-2 diabetes (mean duration of 4 years) were randomized to receive placebo or 5 mg saxagliptin for 6 weeks. Retinal arteriolar structure and retinal capillary flow (RCF) at baseline and during flicker-light exposure was assessed by scanning laser Doppler flowmetry. Central hemodynamics were assessed by pulse wave analysis. Results Postprandial blood glucose (9.27 ± 0.4 versus 10.1 ± 0.4 mmol/L; p = 0.001) and HbA1c (6.84 ± 0.15 (51 ± 1.6) versus 7.10 ± 0.17% (54 ± 1.9 mmol/mol); p < 0.001) were significantly reduced with saxagliptin treatment compared to placebo. RCF was significantly reduced after treatment with saxagliptin (288 ± 13.2 versus 314 ± 14.1 AU; p = 0.033). This was most pronounced in a subgroup of patients (n = 32) with a fall in postprandial blood glucose (280 ± 12.1 versus 314 ± 16.6 AU; p = 0.011). No significant changes in RCF were seen during flicker-light exposure between placebo and saxagliptin, but the vasodilatory capacity increased two-fold with saxagliptin treatment. Central augmentation pressure tended to be lower after treatment with saxagliptin (p = 0.094), and central systolic blood pressure was significantly reduced (119 ± 2.3 versus 124 ± 2.3 mmHg; p = 0.038). Conclusions Our data suggest that treatment with saxagliptin for 6 weeks normalizes retinal capillary flow and improves central hemodynamics in type-2 diabetes. Trial registration The study was registered at (ID: NCT01319357).
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Affiliation(s)
| | | | | | | | | | | | | | - Roland E Schmieder
- Department of Nephrology and Hypertension, University of Erlangen-Nuremberg, Ulmenweg 18, Erlangen, Germany.
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Berndt-Zipfel C, Michelson G, Dworak M, Mitry M, Löffler A, Pfützner A, Forst T. Vildagliptin in addition to metformin improves retinal blood flow and erythrocyte deformability in patients with type 2 diabetes mellitus - results from an exploratory study. Cardiovasc Diabetol 2013; 12:59. [PMID: 23565740 PMCID: PMC3637086 DOI: 10.1186/1475-2840-12-59] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 02/06/2023] Open
Abstract
Numerous rheological and microvascular alterations characterize the vascular pathology in patients with type 2 diabetes mellitus (T2DM). This study investigated effects of vildagliptin in comparison to glimepiride on retinal microvascular blood flow and erythrocyte deformability in T2DM. Fourty-four patients with T2DM on metformin monotherapy were included in this randomized, exploratory study over 24 weeks. Patients were randomized to receive either vildagliptin (50 mg twice daily) or glimepiride individually titrated up to 4 mg in addition to ongoing metformin treatment. Retinal microvascular blood flow (RBF) and the arteriolar wall to lumen ratio (WLR) were assessed using a laser doppler scanner. In addition, the erythrocyte elongation index (EI) was measured at different shear stresses using laserdiffractoscopy. Both treatments improved glycaemic control (p < 0.05 vs. baseline; respectively). While only slight changes in RBF and the WLR could be observed during treatment with glimepiride, vildagliptin significantly increased retinal blood flow and decreased the arterial WLR (p < 0.05 vs. baseline respectively). The EI increased during both treatments over a wide range of applied shear stresses (p < 0.05 vs. baseline). An inverse correlation could be observed between improved glycaemic control (HbA1c) and EI (r = −0.524; p < 0.0001) but not with the changes in retinal microvascular measurements. Our results suggest that vildagliptin might exert beneficial effects on retinal microvascular blood flow beyond glucose control. In contrast, the improvement in erythrocyte deformability observed in both treatment groups, seems to be a correlate of improved glycaemic control.
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Lijia Z, Zhao S, Wang X, Wu C, Yang J. A self-propelling cycle mediated by reactive oxide species and nitric oxide exists in LPS-activated microglia. Neurochem Int 2012; 61:1220-30. [PMID: 23000131 DOI: 10.1016/j.neuint.2012.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 08/29/2012] [Accepted: 09/05/2012] [Indexed: 10/27/2022]
Abstract
It has been widely accepted that microglia, the innate immune cells in the brain, can be chronically activated in response to neuron death, fuelling a self-renewing cycle of microglial activation followed by further neuron damage (reactive microgliosis), which has been considered as the main reason responsible for the progressive nature of neurodegenerative diseases. In the present study, it was found that LPS (lipopolysaccharide) significantly induced the activation of N9 microglia, and the increase of NO level induced by pretreatment of LPS could last after the removal of LPS. The culture medium of activated microglia significantly decreased the viability of rat primary cortical neuron. These results can be blocked by the antioxidant N-acetylcysteine (NAC) and nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase inhibitor diphenyleneiodonium sulfate (DPI), suggesting that intracellular reactive oxide species (iROS) released from the activated microglial cells may continue to further activate microglia. Next, it was shown that the iROS level increased rapidly after the LPS treatment in microglia cells followed by the NO production through the regulation of iNOS (inducible nitric oxide synthase) expression. The increase of iROS could be reversed by gp91phox (the critical and catalytic subunit of NADPH oxidase) siRNA. Moreover, NO released from sodium nitroprusside (SNP) was able to increase the iROS production of N9 microglia by regulating of the activity and the expression of NADPH oxidase. In conclusion, our research suggests for the first time that there may exist a self-propelling cycle in microglial cells possibly mediated by iROS and NO when they become activated by LPS. It may be responsible partially for the ongoing microglial activation and the progressive nature of neurodegenerative diseases.
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Affiliation(s)
- Zhang Lijia
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, People's Republic of China
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Influence of blood flow on arteriolar wall-to-lumen ratio in the human retinal circulation in vivo. Microvasc Res 2012; 83:111-7. [DOI: 10.1016/j.mvr.2011.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/22/2011] [Accepted: 10/13/2011] [Indexed: 11/24/2022]
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Current World Literature. Curr Opin Nephrol Hypertens 2012; 21:106-18. [DOI: 10.1097/mnh.0b013e32834ee42b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Vascular dysfunction due to elevated blood pressure constitutes an early step in the pathogenesis of atherosclerotic disease. A better understanding of the pathophysiology and of clinical correlates of vascular remodeling in retinal arteries and arterioles offers the opportunity for a better risk stratification and treatment. In vivo vascular changes can be best detected by direct imaging techniques. In this review, we summarize the main findings of several recent studies analyzing retinal-arteriolar parameters, such as outer diameter (OD) and lumen diameter (LD), retinal capillary flow (RCF), wall-to-lumen-ratio, and wall cross-sectional area by using scanning laser Doppler flowmetry (SLDF). Blood pressure emerged as an independent determinant of the wall-to-lumen ratio (WLR) of retinal arterioles. Retinal arterioles and small arteries of hypertensive subjects showed eutrophic inward remodeling as indicated by increased WLR, decreased LD and almost unchanged wall cross-sectional area compared to normotensive subjects. These findings are in accordance with those observed in small-resistance vessels analyzed ex vivo. In hypertensive patients, an increased retinal vascular resistance has been documented and basal nitric oxide activity emerged as an independent determinant of early arteriolar remodeling. Thus, SLDF emerged as a noninvasive research tool to assess early vascular changes in the retinal circulation.
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