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Dündar NB, Sarphie D, Yüce K, Gaygısız Ü, Kaskatı OT, Türkoğlu M, Bıkmaz GA, Karabıyık L, Çağlar K, Bozdayı G, Mian R, Moss P, İlhan MN. Assessing neutrophil-derived ROS production at the bedside: a potential prognostic tool in severe COVID-19 cases. Intensive Care Med Exp 2023; 11:69. [PMID: 37801184 PMCID: PMC10558411 DOI: 10.1186/s40635-023-00554-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 09/27/2023] [Indexed: 10/07/2023] Open
Abstract
PURPOSE A prompt and effective immune response is required for clearance of pathogens but exaggerated states of inflammation can cause extensive collateral damage to the host. We have previously used a rapid near-patient assay that measures the functional capacity of neutrophils to produce reactive oxygen species (ROS) to show that values are elevated in patients with severe COVID-19 or sepsis. Here, we assess the utility of longitudinal ROS measurements to monitor and predict mortality outcome for patients with COVID-19 infection being treated in an ICU setting. METHODS We used the Leukocyte ImmunoTest™ (LIT™) to quantify neutrophil ROS release using a small volume (10 µL) of capillary blood in a portable, rapid (10-min) format. RESULTS ROS values (LIT score) and ROS levels assessed in relation to neutrophil count (LIT/N) were both markedly elevated in the patient group. Furthermore, these correlated strongly with peripheral neutrophil count and CRP value. Serial measurement of neutrophil or CRP values were not able to reliably predict mortality within the study. In contrast, LIT and LIT/N values started to decline at 7 and 5 days, respectively, in patients who survived ICU admission and this increment increased further thereafter. CONCLUSIONS This study raises the possibility of LIT and LIT/N to be used as a predictive clinical tool for patients with severe COVID-19 and argues for its assessment to inform on prognosis, and potentially guide treatment pathways, in other disorders associated with neutrophil activation. TAKE-HOME MESSAGE A longitudinal study of 44 severe COVID-19 patients in the ICU of a leading teaching hospital has demonstrated the prognostic potential of a rapid bedside assay of neutrophil-derived reactive oxygen species (ROS). Assessment of changes in ROS production, as measured using the Leukocyte ImmunoTest™, shows that ROS production generally declined back to normal levels for patients who survived, but remained elevated for those patients who did not survive.
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Affiliation(s)
- Nazlıhan Boyacı Dündar
- Department of Internal Medicine, Division of Intensive Care Medicine, Faculty of Medicine, Gazi University, Ankara, Turkey
| | | | - Kenan Yüce
- Department of Clinical Microbiology, Division of Virology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Ümmügülsüm Gaygısız
- Department of Anesthesiology and Reanimation, Division of Intensive Care Medicine, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - O Tolga Kaskatı
- Department of Biostatistics, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey
| | - Melda Türkoğlu
- Department of Internal Medicine, Division of Intensive Care Medicine, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Gülbin Aygencel Bıkmaz
- Department of Internal Medicine, Division of Intensive Care Medicine, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Lale Karabıyık
- Department of Anesthesiology and Reanimation, Division of Intensive Care Medicine, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Kayhan Çağlar
- Department of Clinical Microbiology, Division of Virology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Gülendam Bozdayı
- Department of Clinical Microbiology, Division of Virology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | | | - Paul Moss
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Mustafa Necmi İlhan
- Department of Public Health, Faculty of Medicine, Gazi University, Ankara, Turkey
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Light A, Sarphie DF, Mian R, Li X, Otieno M, Ahmed HU, Shah TT. The 'Leucocyte Coping Capacity' test for identifying radiorecurrent prostate cancer: a pilot study. BJU Int 2023; 132:268-271. [PMID: 37169727 PMCID: PMC11034710 DOI: 10.1111/bju.16043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Alexander Light
- Imperial Prostate, Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK
- Imperial Urology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London UK
| | | | | | | | - Marjorie Otieno
- Division of Surgery and Interventional Sciences, University College London, London, UK
| | - Hashim U. Ahmed
- Imperial Prostate, Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK
- Imperial Urology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London UK
- Division of Surgery and Interventional Sciences, University College London, London, UK
| | - Taimur T. Shah
- Imperial Prostate, Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK
- Imperial Urology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London UK
- Division of Surgery and Interventional Sciences, University College London, London, UK
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Light A, Sarphie D, Mian R, Li X, Otieno M, Ahmed H, Shah T. Leukocyte ImmunoTest scores: A novel point-of-care test for evaluating radiorecurrent prostate cancer. An analysis from the FOcal RECurrent Assessment and Salvage Treatment (FORECAST) trial. Eur Urol 2023. [DOI: 10.1016/s0302-2838(23)01230-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Veenith T, Martin H, Le Breuilly M, Whitehouse T, Gao-Smith F, Duggal N, Lord JM, Mian R, Sarphie D, Moss P. High generation of reactive oxygen species from neutrophils in patients with severe COVID-19. Sci Rep 2022; 12:10484. [PMID: 35729319 PMCID: PMC9212205 DOI: 10.1038/s41598-022-13825-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 05/27/2022] [Indexed: 12/25/2022] Open
Abstract
Neutrophilia and an elevated neutrophil:lymphocyte ratio are both characteristic features of severe COVID-19 infection. However, functional neutrophil responses have been poorly investigated in this setting. We utilised a novel PMA-based stimulation assay to determine neutrophil-derived reactive oxygen species (ROS) generation in patients with severe COVID-19 infection, non-COVID related sepsis and healthy study participants. ROS production was markedly elevated in COVID-19 patients with median values ninefold higher than in healthy controls and was particularly high in patients on mechanical ventilation. ROS generation correlated strongly with neutrophil count and elevated levels were also seen in patients with non-COVID related sepsis. Relative values, adjusted for neutrophil count, were high in both groups but extreme low or high values were seen in two patients who died shortly after testing, potentially indicating a predictive value for neutrophil function. Our results show that the high levels of neutrophils observed in patients with COVID-19 and sepsis exhibit functional capacity for ROS generation. This may contribute to the clinical features of acute disease and represents a potential novel target for therapeutic intervention.
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Affiliation(s)
- Tonny Veenith
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
- Birmingham Acute Care Research, University of Birmingham, Birmingham, UK
| | - Helena Martin
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
- Birmingham Acute Care Research, University of Birmingham, Birmingham, UK
| | - Martin Le Breuilly
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
- Birmingham Acute Care Research, University of Birmingham, Birmingham, UK
| | - Tony Whitehouse
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
- Birmingham Acute Care Research, University of Birmingham, Birmingham, UK
| | - Fang Gao-Smith
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
- Birmingham Acute Care Research, University of Birmingham, Birmingham, UK
| | - Niharika Duggal
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
| | - Janet M Lord
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
| | | | | | - Paul Moss
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
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Lahiri S, Reisig DD, Dean LL, Reay-Jones FPF, Greene JK, Carter TE, Mian R, Fallen BD. Mechanisms of Soybean Host-Plant Resistance Against Megacopta cribraria (Hemiptera: Plataspidae). Environ Entomol 2020; 49:876-885. [PMID: 32623469 DOI: 10.1093/ee/nvaa075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Indexed: 06/11/2023]
Abstract
A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management.
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Affiliation(s)
- S Lahiri
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - D D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Lisa L Dean
- USDA-ARS, Market Quality and Handling Research Unit, Raleigh, NC
| | - F P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - J K Greene
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville, SC
| | - T E Carter
- USDA-ARS, Soybean and Nitrogen Fixation Research Unit, Raleigh, NC
| | - R Mian
- USDA-ARS, Soybean and Nitrogen Fixation Research Unit, Raleigh, NC
| | - B D Fallen
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
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Lahiri S, Reisig DD, Reay-Jones FPF, Greene JK, Carter TE, Mian R, Fallen BD. Soybean Host Plant Resistance to Megacopta cribraria (Hemiptera: Plataspidae) and the Potential Role of Leaf Trichome Density. Environ Entomol 2020; 49:88-97. [PMID: 31904078 DOI: 10.1093/ee/nvz158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Megacopta cribraria (F.) (Hemiptera: Plataspidae) is an invasive pest of soybean that has spread across the southeastern United States since its initial discovery in 2009 in Georgia. Previous studies in the southeastern states have documented both the population dynamics of this pest and host plant resistance (HPR) among soybean varieties, although the specific mechanisms of HPR remain unknown. The objectives of this study were, therefore, to 1) quantify field resistance to M. cribraria in multiple soybean varieties in two states previously affected by severe M. cribraria infestations, North Carolina (NC) and South Carolina (SC); and 2) study the role of soybean trichome density in imparting resistance against M. cribraria. Soybean variety 'Camp' was least attractive to M. cribraria, through time and locations, suggesting consistent resistance. Other varieties showed variable performance among the locations and sampling dates. A significant difference in trichome density was evident. However, there was no correlation between trichome density and M. cribraria infestation. Compared to a previously published study in the same location, when M. cribraria adults emerging from overwintering dispersed into soybeans, in our study only first-generation adults dispersed into soybeans. Considering the current trend of significantly lower M. cribraria infestation rates in North and South Carolina, this pest may be finally succumbing to indigenous natural enemies and should be managed by incorporating integrated pest management tactics, such as HPR, that help conserve natural enemy populations.
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Affiliation(s)
- S Lahiri
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - D D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - F P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - J K Greene
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville, SC
| | - T E Carter
- USDA-ARS, Soybean and Nitrogen Fixation Research, Raleigh, NC
| | - R Mian
- USDA-ARS, Soybean and Nitrogen Fixation Research, Raleigh, NC
| | - B D Fallen
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
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Shelton-Rayner GK, Mian R, Chandler S, Robertson D, Macdonald DW. Quantifying Transient Psychological Stress Using a Novel Technique: Changes to PMA-Induced Leukocyte Production of ROS In Vitro. International Journal of Occupational Safety and Ergonomics 2015; 17:3-13. [DOI: 10.1080/10803548.2011.11076866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Montes I, Newman C, Mian R, Macdonald DW. Radical health: ecological corollaries of body condition, transport stress and season on plasma antioxidant capacity in the European badger. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.2010.00787.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Shelton-Rayner GK, Macdonald DW, Chandler S, Robertson D, Mian R. Leukocyte reactivity as an objective means of quantifying mental loading during ergonomic evaluation. Cell Immunol 2010. [PMID: 20299010 DOI: 10.1016/j.cellimm.2010.02.011)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Psychological stress evokes rapid changes to the cardiovascular and neuroendocrine systems, responses that can become habituated following repeated exposure. This study, comprising of two phases, suggests that the immune system follows a similar trend. Phase 1: 15 healthy subjects (aged between 26 and 56years) provided capillary blood samples before and after completing three basic tasks using, in turn, two automotive touch screen interfaces (Interface 1-antecedent version, Interface 2-improved version). Using a chemiluminescent technique termed leukocyte coping capacity (LCC), the ability of leukocytes to produce reactive oxygen species in vitro was assessed. Significant differences in leukocyte activity were shown between treatment groups, where the greatest post-test decrease occurred after using Interface 1. Phase 2: a randomly selected sub-group (n=4) underwent weekly repeat testing using both interfaces. Significant differences in post-test leukocyte reactivity were exhibited between test weeks for each interface-the magnitude of response decreasing with successive exposure.
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Affiliation(s)
- G K Shelton-Rayner
- Department of Biomolecular and Sport Sciences, Faculty of Health and Life Sciences, Coventry University, Cox St, Coventry CV1 5FB, UK
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Shelton-Rayner G, Macdonald D, Chandler S, Robertson D, Mian R. Leukocyte reactivity as an objective means of quantifying mental loading during ergonomic evaluation. Cell Immunol 2010; 263:22-30. [DOI: 10.1016/j.cellimm.2010.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 02/05/2010] [Accepted: 02/19/2010] [Indexed: 11/17/2022]
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Moorhouse TP, Gelling M, McLaren GW, Mian R, Macdonald DW. Physiological consequences of captive conditions in water voles (Arvicola terrestris). J Zool (1987) 2007. [DOI: 10.1111/j.1469-7998.2006.00175.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ellard D, Barlow J, Mian R, Patel R. Perceived stress, psychological well-being and the activity of neutrophils in patients undergoing cardiopulmonary bypass surgery. Stress Health 2006. [DOI: 10.1002/smi.1089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Thake CD, Mian T, Garnham AW, Mian R. Leukocyte counts and neutrophil activity during 4 h of hypocapnic hypoxia equivalent to 4000 m. Aviat Space Environ Med 2004; 75:811-7. [PMID: 15460635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
INTRODUCTION Symptoms and signs of infectious disease are increased in subjects at altitude. Most infections at altitude are diagnosed clinically and do not have objective data to support the diagnosis. Since in vivo innate immune responses to hypoxia have not been thoroughly characterized, we investigated the effect of acute systemic hypocapnic hypoxia on leukocyte trafficking and neutrophil activity in healthy humans at rest. METHODS Sixteen male subjects [mean +/- SD age 28.3 +/- 6.5 yrs, body mass 80.9 +/- 15.9 kg, Vo2peak 4.10 +/- 0.76 L x min(-1)] breathed a hypoxic gas mixture (F(IO)2 = 12.2%, equivalent to 4000 m; H) or normoxic room air (F(IO)2 = 20.9%; N) for 240 min, via a mouthpiece, followed by 60 min of normal breathing. RESULTS H induced a differential response in peripheral venous blood neutrophils (p < 0.05), lymphocytes (p < 0.01), and eosinophils (p < 0.01; 60-240 min), resulting in a relative lymphopenia (H 1.88 +/- 0.48 and N 2.14 +/- 0.45 x 10(9) L(-1)) and neutrophilia (H 5.2 +/- 1.8 and N 3.9 +/- 1.1 x 10(9) L(-1)) by 240 and 300 min, respectively. Unstimulated leukocyte oxidative activity, as determined by luminol enhanced chemiluminescence; plasma elastase, a marker of in vivo neutrophil degranulation; and sP-selectin, a marker of endothelial cell activation, did not change throughout. DISCUSSION Differences in immune cell numbers showed a marked similarity to changes previously reported in response to intense short- and long-duration exercise and were attributed to the physiological responses induced by acute hypoxia that are known to mediate immune cell trafficking. These findings could be relevant to the etiology of conditions where hypoxia and immune cells are implicated.
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Affiliation(s)
- C Douglas Thake
- School of Science and Environment, University of Coventry, Priory St, Coventry CV1 5FB, UK.
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McLaren GW, Macdonald DW, Georgiou C, Mathews F, Newman C, Mian R. Leukocyte coping capacity: a novel technique for measuring the stress response in vertebrates. Exp Physiol 2003; 88:541-6. [PMID: 12861342 DOI: 10.1113/eph8802571] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Methods used to quantify the stress response in animals are vital tools in many areas of biology. Here we describe a new method of measuring the stress response, which provides rapid results and can be used in the field or laboratory. After a stressful event, we measure the capacity of circulating leukocytes to produce a respiratory burst in vitro in response to challenge by phorbol myristate acetate (PMA). During the respiratory burst leukocytes produce oxygen free radicals, and the level of production can be measured directly as chemiluminescence. When in vitro PMA-stimulated whole blood chemiluminescence is measured directly after a stressful event, we define the response as the leukocyte coping capacity (LCC). In an experiment badgers (Meles meles), which were caught as part of an on-going population study, were either transported to a central site prior to blood sampling or blood was collected at their site of capture. Transported animals had a significantly lower LCC and showed changes in leukocyte composition that were indicative of stress. We conclude that the stress of transport reduced LCC in badgers and that LCC serves as a quantitative measure of stress. Potential applications of this method are discussed.
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Affiliation(s)
- G W McLaren
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Abstract
The aim of this study was to assess the effect of watching a psychological stressful event on the activation of leukocytes in healthy human volunteers. Blood samples were obtained from 32 healthy male and female subjects aged between 20 and 26 years before, during and after either watching an 83-minute horror film that none of the subjects had previously seen (The Texas Chainsaw Massacre, 1974) or by sitting quietly in a room (control group). Total differential cell counts, leukocyte activation as measured by the nitroblue tetrazolium (NBT) test, heart rate and blood pressure (BP) measurements were taken at defined time points. There were significant increases in peripheral circulating leukocytes, the number of activated circulating leukocytes, haemoglobin (Hb) concentration and haematocrit (Hct) in response to the stressor. These were accompanied by significant increases in heart rate, systolic and diastolic BP (P<0.05 from baseline). This is the first reported study on the effects of observing a psychologically stressful, albeit fictitious event on circulating leukocyte numbers and the state of leukocyte activation as determined by the nitrotetrazolium test.
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Affiliation(s)
- Rubina Mian
- School of Science and The Environment, Coventry University, Cox St., Coventry CV1 5FB, UK.
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Abstract
Circumstantial evidence suggests that in vivo hypoxia can activate human leukocytes to release a host of mediators including oxygen free radicals. Endothelial cells have always been presumed to play an important role in hypoxia-induced leukocyte activation. The primary aim of this study was to determine whether acute exposure of whole blood to a hypoxic mixture could stimulate the production of oxygen free radicals in the absence of endothelial cells, and to determine the role of Ca2+ in this process. Freshly drawn whole blood was obtained by venepuncture from 30 healthy volunteers. Exposure of blood to 6% O2 in a purpose built environmental chamber for periods of 8, 10, 15, 30, and 45 min resulted in a significant increase in the production of oxygen free radicals. This response was significantly increased after a 10-min incubation with the Ca2+ ionophore (A23187), supporting the idea that the influx of extracellular Ca2+ is an important step in the process. Incubation of human leukocytes with verapamil (10 min) and subsequent exposure to hypoxia resulted in the significantly reduction in hypoxia-induced production of oxygen free radicals at 15 min and a paradoxical increase at 30- and 45-min exposures. The significance of the results is discussed.
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Affiliation(s)
- Dimitrios Sanidas
- Department of Biomedical Science, School of Science and Environment Cox St., Coventry University, Cox St., CV1 5FB., Coventry, UK
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Abstract
Twenty-five undergraduates and university staff (15 females, 10 males) volunteered to take part in a study examining the effects of a short-term mental stressor on the activation of neutrophils in peripheral blood, as determined by the oxidative capacity to reduced Nitro-blue Tetrazolium (NBT). Participants were assigned to one of two groups, an experimental group (n=17) and a control group (n=8). Subjects in the experimental group were subjected to a time-constrained mental stressor and finger-stick blood samples were taken on four occasions. Those in the control group did not complete a stressor task and only experienced the four finger-stick blood samples. Heart rate was recorded at 5-min intervals as a general indicator of arousal. Examination of the stained blood samples showed that a short-term stressor resulted in significant increased activation of neutrophils, which returned almost to baseline levels on completion of the experiment. In contrast, the control group's neutrophils showed no significant change in activation throughout. The results support the hypothesis that short-term, acute stressors may activate neutrophils.
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Affiliation(s)
- D R Ellard
- Department of Biomedical Sciences, School of Natural & Environmental Sciences. Coventry University, Priory Street, Coventry, CV1 5FB, UK.
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Mian R, Morrison WA, Hurley JV, Penington AJ, Romeo R, Tanaka Y, Knight KR. Formation of new tissue from an arteriovenous loop in the absence of added extracellular matrix. Tissue Eng 2000; 6:595-603. [PMID: 11103081 DOI: 10.1089/10763270050199541] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A major requirement for the microsurgical repair of contour defects of the skin, for example, following removal of a skin cancer on the face, is a mass of vascularised subcutaneous tissue. Such tissue can be generated in vivo using basic tissue engineering principles. In previous studies in our laboratory, we have used a model comprising an arteriovenous (AV) shunt loop sandwiched in artificial dermis, placed in a cylindrical plastic growth chamber, and inserted subcutaneously to grow new connective tissue progressively up to 4 weeks. To learn more about the basic growth characteristics with this model, the same AV shunt loop within a chamber without added extracellular matrix was inserted subcutaneously into the groins of rats for 2, 4, or 12 weeks (n = 5 per group). There was a progressive increase in the mass and volume of tissue such that the chamber was two-thirds full after 12 weeks. Histological examination showed that at 2 weeks there was evidence of fibroblast and vascular outgrowth from the AV shunt, with the formation of granulation tissue, surrounded by a mass of coagulated exudate. At 4 weeks the connective tissue deposition was more extensive, with a mass of more mature granulation tissue containing considerable collagen. By 12 weeks there was an extensive, well vascularized mass of mature fibrous tissue. The blood vessels and residual adventitia of the AV shunt were the likely source of growth factors and of the cells which populated the chamber with new maturing connective tissue. A patent AV shunt in an isolated chamber appears to be the minimal requirement for the generation of new vascularized tissue that is potentially suitable for microsurgical transplantation.
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Affiliation(s)
- R Mian
- Bernard O'Brien Institute of Microsurgery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
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Sanidas D, Garnham A, Mian R. Activation of human leukocytes by acute hypoxia. Exp Physiol 2000; 85:263-6. [PMID: 10825412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Exposure of human leukocytes to 12% and 6% O(2) in vitro resulted in striking ultrastructural and morphological changes. These changes included the appearance of crater-like holes, a reduction in granular size and disruption of the cellular membrane. The implications of these findings is discussed.
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Affiliation(s)
- D Sanidas
- Department of Biomedical Sciences, School of Natural & Environmental Sciences, Coventry University, Cox Street Coventry, CV1 5FB, Birmingham, UK
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Kavanagh BP, Ngo C, Raymer K, Yang H, Alhashemi JA, Lui ACP, Reid D, Cicutti N, Krepski B, Wood G, Heyland DK, Badner NH, Murkin JM, Mohr J, McKenzie FN, van der Starre PJA, van Rooyen-Butijn WT, Wilson-Yang K, Teoh K, Lee RMKW, Hossain I, Cheng D, Karski J, Asokumar B, Sandier A, St-Amand MA, Murkin JM, Menkis AH, Downey DB, Nantau W, Adams S, Dowd N, Cheng D, Wong D, Carroll-Munro J, Trachuk C, Cregg N, Cheng DCH, Williams WG, Karski JM, Siu S, Webb G, Cheng DCH, Wong DT, Kustra R, Karski J, Tibshirani RJ, Côté DL, Lacey DE, LeDez KM, Smith JA, Crosby ET, Orkin FK, Fisher A, Volgyesi G, Silverman J, Edelstein S, Rucker J, Sommer L, Dunington S, Roy L, Crochetière C, Arsenault MY, Villeneuve E, Lortie L, Grange CS, Douglas MJ, Adams TJ, Merrick PM, Lucas SB, Morgan PJ, Halpern S, Lo J, Giesinger CL, Halpern SH, Breen TW, Vishnubala S, Shetty GR, De Kock M, Lagmiche A, Scholtes JL, Grodecki W, Duffy PJ, Hull KA, Hawboldt GS, Clark AJ, Smith JB, Norman RW, Beattie WS, Sandier A, Jewett M, Valiquette L, Katz J, Fradet Y, Redelmeier D, Sampson H, Cole J, Chedore T, Snedden W, Green RG, Sosis MB, Robles PI, Lazar ER, Jolly DT, Tarn YK, Tawfik SR, Clanachan AS, Milne A, Beamish T, Cuillerier DJ, Sharpe MD, Lee JK, Basta M, Krahn AD, Klein GJ, Yee R, Vakharia N, Francis H, Scheepers L, Vaghadia H, Carrier J, Martin R, Pirlet M, Claprood Y, Tétrault JP, Wong TD, Ryner L, Kozlowski P, Scarth G, Warrian RK, Lefevre G, Thiessen D, Girling L, Doiron L, McCudden C, Saunders J, Mutch WAC, Duffy PJ, Langevin S, Lessard MR, Trépanier CA, Hare GMT, Ngan JCS, Viskari D, Berrill A, Jodoin C, Couture J, Bellemare F, Farmer S, Muir H, Money P, Milne B, Parlow J, Raymond J, Williams JM, Craen RA, Novick T, Komar W, Frenette L, Cox J, Lockhart B, McArdle P, Eckhoff D, Bynon S, Dobkowski WB, Grant DR, Wall WJ, Chedrawy EG, Hall RI, Nedelcu V, Parlow J, Viale JP, Bégou G, Sagnard P, Hughson R, Quintin L, Troncy É, Collet JP, Shapiro S, Guimond JG, Blair L, Ducruet T, Francœur M, Charbonneau M, Blaise G, Snedden W, Bernadska E, Manson HI, Kutt JL, Mezon BY, Nishida O, Arellano R, Boylen P, DeMajo W, Archer DP, Roth SH, Raman S, Manninen P, Boyle K, Cenic A, Lee TY, Gelb AW, Reinders FX, Brown JIM, Baker AJ, Moulton RJ, Schlichtert L, Schwarz SKW, Puil E, Finegan BA, Finucane BT, Kurrek MM, Devitt JH, Morgan PJ, Cleave-Hogg D, Bradley J, Byrick R, Spadafora SM, Fuller JG, Gelula MH, Mayson K, Forster B, Byrick RJ, McKnight DJ, Kurrek M, Kolton M, Cleave-Hogg D, Haughton J, Halpern S, Kronberg J, Shysh S, Eagle C, Dagnone AJ, Parlow JL, Blaise G, Yang F, Nguyen H, Troncy E, Czaika G, Wachowski I, Basta M, Krahn AD, Yee R, Deladrière H, Cambier C, Pendeville P, Hung OR, Coonan E, Whynot SC, Mezei M, Coonan E, Whynot SC, Ho AMH, Luchsinger IS, Ling E, Mashava D, Chinyanga HM, Cohen MM, Shaw M, Robblee JA, Labow RS, Rubens FD, Diemunsch AM, Gervais R, Rose DK, Cohen MM, O’Brien-Pallas L, Copplestone C, Rose DK, Karkouti K, Sykora K, Cheung SLW, Booker PD, Franks R, Pozzi M, Guard B, Sikich N, Lerman J, Levine M, Swan H, Cox P, Montgomery C, Dunn G, Bourne R, Kinahan A, McCormack J, Dunn GS, Reimer EJ, Sanderson P, Sanderson PM, Montgomery CJ, Betts TA, Orlay GR, Wong DH, Cohen M, Al-Kaisy AA, Chan V, Peng P, Perlas A, Miniad A, Cushing EV, Mills KR, El-Beheiry H, Jahromi SS, Weaver J, Morris M, Carien PL, Cowan RM, Manninen P, Richards J, Robblee JA, Labow RS, Rubens FD, Menkis AH, Adams S, Henderson BT, Hudson RJ, Thomson IR, Moon M, Peterson MD, Rosenbloom M, Davison PJ, Ali M, Ali NS, Searle NR, Thomson I, Roy M, Gagnon L, Lye A, Walsh F, Middleton W, Wong D, Langer A, Errett L, Mazer CD, Karski J, Tibshirani RJ, Williamson KM, Smith G, Gnanendran KP, Bignell SJ, Jones S, Sleigh J, Arnell M, Schultz JAI, Fear DW, Ganapathy S, Moote C, Wassermann R, Watson J, Armstrong K, Calikyan AO, Yilmaz O, Kose Y, Peng P, Chan V, Chung F, Claxton AR, Krishnathas A, Mezei G, Badner NH, Paul TL, Doyle JA, Mehta M, DeLima LGR, Silva LEO, May WL, Maliakkal RJ, Mehta M, Kolesar R, Arellano R, Rafuse S, Fletcher M, Dunn G, Curran M, Bragg P, Chamberlain W, Crossan M, Ganapathy S, Sandhu H, Spadafora S, Mian R, Evans B, Hurst L, Katsiris S. Abstracts. Can J Anaesth 1997. [DOI: 10.1007/bf03022274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Abstract
1. In rats housed in a hypoxic chamber at 12% O2 for 3-5 weeks (CH) and in normal rats housed in air (N), we directly observed responses of arterial and venous vessels of the spinotrapezius muscle to changes in O2 concentration in the inspirate. Both CH and N rats were anaesthetized with Saffan. They had haematocrits of 55.0 +/- 0.9% (mean +/- S.E.M.) and 41.9 +/- 0.5%, respectively. 2. In CH rats breathing 12% O2 and N rats breathing air, arterial and venous vessels from comparable anatomical positions in the vascular tree were of similar internal diameter. They also showed similar maximum dilator responses to topical adenosine (10(-3) M); 14.1 +/- 1.1 and 16.3 +/- 1.7% in all arterioles, 15.5 +/- 1.2 and 11.5 +/- 0.6% in all venules in CH and N rats, respectively. 3. In CH rats, the change from 12% O2 to air for 3 min induced constriction in all arterioles and venules (-12.9 +/- 1.0 and -14.3 +/- 1.7%, respectively), whereas in N rats, the change from air to 12% O2 for 3 min induced net dilatation (3.9 +/- 1.8% in arterioles and 4.7 +/- 0.8% in venules). Topical application of the adenosine receptor antagonist 8-sulphophenyltheophylline (8-SPT, 10(-3) M) had no effect on control diameters in CH or N rats, nor on constrictor responses to air in CH, but reversed or reduced dilator responses to 12% O2 in N rats (to -2.4 +/- 1.3% in arterioles and 2.0 +/- 0.9% in venules). 4. In CH rats, the change from 12 to 8% O2 produced net dilatation as great as that induced in N rats by the larger change from air to 8% O2: 8.5 +/- 2.6 and 5.0 +/- 3.7% in arterioles and 10.3 +/- 1.8 and 6.4 +/- 1.9% in venules, respectively. These responses were similarly reduced by 8-SPT to -4.3 +/- 1.9 and -5.2 +/- 2.7% in arterioles and to -6.9 +/- 2.0 and -1.5 +/- 2.0% in venules, respectively. 5. These results indicate that CH rats were acclimated to 12% O2 such that the resting tone of arterial and venous vessels of muscle was comparable to that of N rats breathing air. They also suggest that adenosine had little tonic dilator influence in CH rats breathing 12% O2 despite its contribution to the dilatation induced in N rats by acute exposure to 12% O2. This may reflect the greater haematocrit in CH rats which normalized the O2 supply to muscle. However, CH rats were more sensitive than N rats to the dilator influence of acute systemic hypoxia and this was largely mediated by adenosine.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham, UK
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23
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Abstract
1. We have compared the roles of adenosine in mediating dilator responses to acute hypoxia in mesenteric microcirculation of control, normoxic (N) rats and in chronically hypoxic (CH) rats kept in an hypoxic chamber at 10% O2 for 3-4 weeks. 2. In fifteen N rats, acute hypoxia (breathing 6% O2 for 3 min) induced mean increases in the diameter of arterial vessels of mesentery (whose internal diameter was 10-350 microns) of 8.0 +/- 1.9% (mean +/- S.E.M.) and of venous vessels (whose internal diameter was 12-360 microns) of 10.4 +/- 2.6%. These diameter changes were reduced by approximately 30% when the adenosine receptor antagonist 8-sulpho-phenyltheophylline (8-SPT, 10(-3) M) was applied topically to the mesentery. 3. In a further six N rats, topical application of graded concentrations of adenosine (10(-7)-10(-3) M) to the mesentery evoked graded increases in the diameter of all arterial and venous vessels, maximum increases with 10(-3) M being 12.5 +/- 3.3 and 8.4 +/- 4.3%, respectively; these responses were abolished by 8-SPT. 4. By contrast, in fourteen CH rats, the smaller change in inspirate from 10 to 8% O2 induced increases in diameter of arterial and venous vessels which had control diameters that were comparable to those of N rats, of 14.1 +/- 2.4 and 12.9 +/- 2.7%, respectively, and which were virtually equivalent to the responses induced by topical application of 10(-3) M adenosine (13.3 +/- 1.3 and 16.3 +/- 2.0% in arterial and venous vessels, respectively). The changes induced by acute hypoxia were abolished by 8-SPT, as were those induced by adenosine. 5. These results suggest that in the intestinal mesentery, where the blood vessels have negligible tissue parenchyma around them, locally released or synthesized adenosine makes a substantial contribution to the dilatation that is evoked in arteriolar vessels by acute hypoxia and to the active dilatation, or passive distension of the venous vessels. The results also suggest that this contribution is accentuated in chronic hypoxia either by greater release of adenosine or greater vascular sensitivity to it.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham, UK
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Mian R, Westwood D, Stanley P, Marshall JM, Coote JH. Acute systemic hypoxia and the surface ultrastructure and morphological characteristics of rat leucocytes. Exp Physiol 1993; 78:839-42. [PMID: 8311950 DOI: 10.1113/expphysiol.1993.sp003731] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have examined the surface ultrastructure and morphological characteristics of leucocytes obtained from control rats breathing air and rats made acutely hypoxic (breathing 6% O2, for 30 min). Striking ultrastructural and morphological changes occurred in the leucocytes of hypoxic rats. These changes included the appearance of crater-like holes, a reduction in granule size and disruption of the cell membrane. The implications of these findings are discussed.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, University of Birmingham
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25
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Abstract
1. In rats anaesthetized with Saffan, the spinotrapezius muscle was prepared for in vivo microscopy. Systemic hypoxia (breathing 8% O2 for 3 min) induced a fall in arterial pressure and tachycardia, together with constriction in some arterioles and venules of each section of the vascular tree and dilatation in others. 2. The vasopressin V1-receptor antagonist d(CH2)5Tyr(Me)-arginine vasopressin (20 mg kg-1 I.V.) preferentially attenuated constrictor responses induced by hypoxia in both arterioles and venules, but had no significant effect on the dilator responses. Analysis of responses in individual sections of the vascular tree suggested that the V1-receptor antagonist reduced hypoxia-induced constrictor responses in proximal arterioles (> 13 microns diameter) though not in terminal arterioles (< 13 microns), but reduced hypoxia-induced constrictor responses in both the proximal and distal venules (9-130 microns). 3. Infusion of vasopressin at 1.4, 2.8, 5.7 and 11.4 ng min-1 kg-1 i.v. for 3 min, expected to produce plasma concentrations within the range 28-228 pg ml-1, evoked rises in arterial pressure together with decreases in heart rate. There was also vasoconstriction in the proximal arterioles of spinotrapezius that was graded with vasopressin concentration (5-35% decrease in diameter). 4. Infusion of vasopressin at 1.4 mg min-1 kg-1 i.v. for 3 min with the intention of producing a plasma concentration likely to be reached or exceeded during 8% O2, evoked constriction of all proximal arterioles, though not of terminal arterioles, and constriction of all venous vessels. The magnitude of the constriction induced by vasopressin in vessels that dilated during hypoxia was just as great as in those that constricted during hypoxia. 5. We propose that vasopressin released during systemic hypoxia exerts a constrictor influence upon the proximal arterioles and all sections of the venous tree of skeletal muscle. In individual arterioles and venules the constrictor influence of vasopressin and catecholamines may be overcome by the influence of locally released vasodilator metabolites.
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Affiliation(s)
- J M Marshall
- Department of Physiology, Medical School, Birmingham
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Abstract
OBJECTIVE The aim was to investigate the effect of acute systemic hypoxia on vascular permeability to macromolecules and on leucocyte adherence to vascular endothelium in vivo. METHODS Experiments were performed on anaesthetised rats with either the intestinal mesentery or the spinotrapezius muscle prepared for in vivo microscopy. To quantify changes in vascular permeability, fluorescein isothiocyanate conjugated with serum albumin (FITC-albumin) was given intravenously and the microcirculation was viewed using a mercury source for 30 s periods during air breathing; or before, during, and after breathing 6% O2 for 3 or 20 min. On each occasion the number of FITC leakage sites was counted. In separate experiments acridine orange was given to stain leucocytes and the microcirculation was viewed using a mercury source during air breathing and during a 3 min period of systemic hypoxia. The number of leucocytes that adhered to venular walls for > 30 s was counted. Using mesentery, the effects were tested of BW755C, a lipoxygenase inhibitor, and of SM9064, a LTB4 receptor antagonist, upon the increase in leucocyte adherence observed during hypoxia. RESULTS In rats that breathed air throughout, the number of leakage sites for FITC-albumin in both the spinotrapezius and mesentery remained constant. Moreover, in rats that breathed 6% O2 for 3 or 20 min, the number of leakage sites was not changed in either mesentery or spinotrapezius by hypoxia, but was substantially increased in both preparations by topical application of histamine. However, the number of leucocytes that adhered to the inside of venular walls was significantly increased in both mesentery and spinotrapezius by a 3 min inhalation 6% O2 from 2.83(SEM 0.56) to 4.66(1.77) per 100 microns length of venule and from 2.44(0.33) to 3.35(0.49) respectively during the first period of hypoxia. Between periods of hypoxia the number of adherent leucocytes returned to control in both preparations. Leucocyte adherence was not affected by BW755C (50 or 500 micrograms.ml-1 applied topically or 10 mg.kg-1 intravenously) or by SM9064 (3 mg.kg-1 intravenously). CONCLUSIONS Acute systemic hypoxia does not affect the vascular permeability to albumin. However, 3 min periods of systemic hypoxia induce significant, but reversible, increases in leucocyte adherence in both muscle and mesenteric venules which in mesentery, at least, is not mediated by LTB4 or other products of the lipoxygenase pathway.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, University of Birmingham, United Kingdom
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Abstract
1. In experiments on anaesthetized rats, we have studied the role of adenosine in mediating responses induced in individual arterioles and venules of the spinotrapezius muscle by systemic hypoxia. 2. During systemic hypoxia induced by breathing 6% O2 for 3 min, some arterioles and venules dilated while others constricted. Topical application of the adenosine receptor antagonist, 8 phenyl-theophylline (8-PT), to the spinotrapezius had no effect on the constrictor responses but greatly reduced the dilator responses. The vessels nearest to the capillary bed-terminal arterioles and collecting venules--were most affected; their mean changes in diameter were reduced from 39 and 8% to 11 and -1.6% respectively. 3. In accord with these results, topical application of adenosine (2 x 10(-7)-2 x 10(-3) M) produced graded dilation of all sections of the arterial and venous trees; the terminal arterioles and collecting venules were most responsive, being dilated at maximum by 31 and 15% respectively. The dilator responses induced in those vessels that constricted during hypoxia were fully comparable with those that dilated during hypoxia. 4. Histochemical analysis of the spinotrapezius revealed that oxidative fibres that most readily release adenosine, glycolytic and mixed fibres were all evenly distributed throughout the muscle. There is no reason to suppose that some vessels are preferentially influenced by oxidative fibres. 5. These results indicate that adenosine plays a major role in dilating both arterioles and venules of muscle during systemic hypoxia. But, they are consistent with the idea that the adenosine that is important is not released from muscle fibres, but synthesized by 5'-nucleotidase localized to the blood vessels; its activity may decrease proximally along the vascular tree and may vary from one vessel to another depending on the local O2 tension.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham
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Abstract
1. Studies have been made in the anaesthetized rat of the roles played by alpha- and beta-adrenoreceptor stimulation in determining diameter changes induced in individual arterioles and venules of the spinotrapezius muscle during systemic hypoxia (breathing 6% O2 for 3 min). 2. Topical application to the spinotrapezius of phentolamine, the alpha-adrenoreceptor antagonist, or sotalol, the beta-adrenoreceptor antagonist, had no effect on the fall in systemic arterial pressure and tachycardia induced by hypoxia. 3. All arterioles and venules showed a decrease in diameter in response to topical application of noradrenaline (10(-6) g ml-1): these responses were abolished by topical application of phentolamine. Moreover, those arterioles and venules that showed a decrease in diameter during hypoxia before phentolamine, showed a significantly smaller decrease, or an increase in diameter after phentolamine. This effect was most marked in primary and secondary arterioles (13-50 microns diameter). 4. All arterioles and venules showed an increase in diameter in response to topical application of isoprenaline (10(-6) g ml-1); these responses were abolished by topical application of sotalol. Moreover, these arterioles and venules that showed an increase in diameter during hypoxia before sotalol, showed a significantly smaller increase or even a decrease in diameter after sotalol. 5. These results suggest that during hypoxia the arterioles of skeletal muscle, especially primary and secondary arterioles, are under the constrictor influence of a reflex increase in sympathetic nerve activity while the venules, which have no sympathetic innervation, are under the constrictor influence of circulating catecholamines. They also suggest that in individual arterioles and venules, these constrictor influences may be overcome by dilatation mediated by the beta-adrenoreceptor influence of circulating catecholamines. 6. Since some arterioles and venules still showed constriction during hypoxia after phentolamine and some still showed dilatation during hypoxia after sotalol, it seems that factors other than catecholamines contribute to the diameter changes. It is suggested that locally released metabolites exert a substantial dilator influence, particularly on terminal arterioles and collecting venules, those vessels nearest to the capillary bed.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham
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Abstract
1. In rats anaesthetized with Saffan, responses induced in individual arterial and venous vessels of the spinotrapezius muscle by systemic hypoxia (breathing 12 or 6% O2 for 3 min) were directly observed by in vivo microscopy. 2. Both 12 and 6% O2 induced gradual tachycardia and a fall in arterial pressure. Concommitantly, in each section of the vascular tree, some vessels showed a gradual increase in diameter, others, a gradual decrease. 3. During 12% O2, mean diameter changes were graded from mean increases of approximately 2% in main arteries (resting diameter 40-90 microns) to approximately 20% in terminal arterioles (7-13 microns) and ranged from mean increases of 5-8% in collecting and secondary venules (9-18 microns, 18-30 microns), to a decrease of approximately 2% in main veins (65-130 microns). 4. During 6% O2, constrictor responses were more common in arterial vessels. Thus, mean changes amounted to diameter decreases of less than 5% in main arteries and secondary arterioles (13-18 microns), and increases of approximately 5% in primary arterioles (22-50 microns) and terminal arterioles. By contrast, diameter increases predominated in venous vessels being graded from approximately 20% in collecting venules to approximately 2% in main veins. 5. In seventeen rats, 6% O2 was administered for eight 3 min periods separated by 30 min control periods. The changes evoked in arterial pressure and heart rate were consistent throughout. Diameter changes evoked in individual arterial and venous vessels were consistent in the first two hypoxic periods. However, diameter changes in the third and successive periods were significantly different from those recorded in the first period: increases in diameter became more common and pronounced. 6. These changes in vessel diameter, especially their variability, are considered in relation to recordings made previously of changes in gross blood flow and vascular conductance of limb muscle during systemic hypoxia.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham
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Abstract
In spontaneously breathing anaesthetized rats, both moderate and severe hypoxia caused increases in [K+] in venous efflux from hindlimb muscle, from 4.3 to 4.6 and from 3.8 to 4.4 mM respectively; the increases were accentuated to 5.2 and 5.7 mM after beta 2-receptor blockade with I.V. sotalol. Sotalol also potentiated the vasodilatation evoked in hindlimb muscle by moderate hypoxia, but reduced that evoked by severe hypoxia. We propose that K+ released from muscle during hypoxia contributed to the local vasodilatation. Further, we suggest that this effect was enhanced in moderate hypoxia by blockade of the beta 2-mediated uptake mechanism for K+ in skeletal muscle, but outweighed in severe hypoxia by blockade of the beta 2-mediated dilator action of circulating catecholamines on vascular muscle.
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Affiliation(s)
- R Mian
- Department of Physiology, Medical School, Birmingham
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