1
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Oksanen L, Auvinen M, Kuula J, Malmgren R, Romantschuk M, Hyvärinen A, Laitinen S, Maunula L, Sanmark E, Geneid A, Sofieva S, Salokas J, Veskiväli H, Sironen T, Grönholm T, Hellsten A, Atanasova N. Combining Phi6 as a surrogate virus and computational large-eddy simulations to study airborne transmission of SARS-CoV-2 in a restaurant. Indoor Air 2022; 32:e13165. [PMID: 36437671 PMCID: PMC10100099 DOI: 10.1111/ina.13165] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 05/18/2023]
Abstract
COVID-19 has highlighted the need for indoor risk-reduction strategies. Our aim is to provide information about the virus dispersion and attempts to reduce the infection risk. Indoor transmission was studied simulating a dining situation in a restaurant. Aerosolized Phi6 viruses were detected with several methods. The aerosol dispersion was modeled by using the Large-Eddy Simulation (LES) technique. Three risk-reduction strategies were studied: (1) augmenting ventilation with air purifiers, (2) spatial partitioning with dividers, and (3) combination of 1 and 2. In all simulations infectious viruses were detected throughout the space proving the existence long-distance aerosol transmission indoors. Experimental cumulative virus numbers and LES dispersion results were qualitatively similar. The LES results were further utilized to derive the evolution of infection probability. Air purifiers augmenting the effective ventilation rate by 65% reduced the spatially averaged infection probability by 30%-32%. This relative reduction manifests with approximately 15 min lag as aerosol dispersion only gradually reaches the purifier units. Both viral findings and LES results confirm that spatial partitioning has a negligible effect on the mean infection-probability indoors, but may affect the local levels adversely. Exploitation of high-resolution LES jointly with microbiological measurements enables an informative interpretation of the experimental results and facilitates a more complete risk assessment.
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Affiliation(s)
- Lotta Oksanen
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | | | - Joel Kuula
- Finnish Meteorological InstituteHelsinkiFinland
| | - Rasmus Malmgren
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Martin Romantschuk
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiLahtiFinland
| | | | | | - Leena Maunula
- Faculty of Veterinary Medicine, Food Hygiene and Environmental HealthUniversity of HelsinkiHelsinkiFinland
| | - Enni Sanmark
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Ahmed Geneid
- Department of Otorhinolaryngology and Phoniatrics – Head and Neck SurgeryHelsinki University HospitalHelsinkiFinland
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Svetlana Sofieva
- Finnish Meteorological InstituteHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Julija Salokas
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Helin Veskiväli
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Tarja Sironen
- Department of Virology, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Department of Veterinary Biosciences, Faculty of Veterinary MedicineUniversity of HelsinkiHelsinkiFinland
| | | | | | - Nina Atanasova
- Finnish Meteorological InstituteHelsinkiFinland
- Faculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
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2
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Launiainen S, Katul GG, Leppä K, Kolari P, Aslan T, Grönholm T, Korhonen L, Mammarella I, Vesala T. Does growing atmospheric CO 2 explain increasing carbon sink in a boreal coniferous forest? Glob Chang Biol 2022; 28:2910-2929. [PMID: 35112446 PMCID: PMC9544622 DOI: 10.1111/gcb.16117] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/04/2022] [Indexed: 05/27/2023]
Abstract
The terrestrial net ecosystem productivity (NEP) has increased during the past three decades, but the mechanisms responsible are still unclear. We analyzed 17 years (2001-2017) of eddy-covariance measurements of NEP, evapotranspiration (ET) and light and water use efficiency from a boreal coniferous forest in Southern Finland for trends and inter-annual variability (IAV). The forest was a mean annual carbon sink (252 [ ± 42] gC m-2a-1 ), and NEP increased at rate +6.4-7.0 gC m-2a-1 (or ca. +2.5% a-1 ) during the period. This was attributed to the increasing gross-primary productivity GPP and occurred without detectable change in ET. The start of annual carbon uptake period was advanced by 0.7 d a-1 , and increase in GPP and NEP outside the main growing season contributed ca. one-third and one-fourth of the annual trend, respectively. Meteorological factors were responsible for the IAV of fluxes but did not explain the long-term trends. The growing season GPP trend was strongest in ample light during the peak growing season. Using a multi-layer ecosystem model, we showed that direct CO2 fertilization effect diminishes when moving from leaf to ecosystem, and only 30-40% of the observed ecosystem GPP increase could be attributed to CO2 . The increasing trend in leaf-area index (LAI), stimulated by forest thinning in 2002, was the main driver of the enhanced GPP and NEP of the mid-rotation managed forest. It also compensated for the decrease of mean leaf stomatal conductance with increasing CO2 and LAI, explaining the apparent proportionality between observed GPP and CO2 trends. The results emphasize that attributing trends to their physical and physiological drivers is challenged by strong IAV, and uncertainty of LAI and species composition changes due to the dynamic flux footprint. The results enlighten the underlying mechanisms responsible for the increasing terrestrial carbon uptake in the boreal zone.
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Affiliation(s)
| | - Gabriel G. Katul
- Department of Civil and Environmental EngineeringDuke UniversityDurhamNorth CarolinaUSA
| | - Kersti Leppä
- Natural Resources Institute FinlandHelsinkiFinland
| | - Pasi Kolari
- Faculty of ScienceInstitute for Atmospheric and Earth System Research/PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Toprak Aslan
- Faculty of ScienceInstitute for Atmospheric and Earth System Research/PhysicsUniversity of HelsinkiHelsinkiFinland
| | | | | | - Ivan Mammarella
- Faculty of ScienceInstitute for Atmospheric and Earth System Research/PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Timo Vesala
- Faculty of ScienceInstitute for Atmospheric and Earth System Research/PhysicsUniversity of HelsinkiHelsinkiFinland
- Faculty of Agriculture and ForestryInstitute for Atmospheric and Earth System Research/Forest SciencesUniversity of HelsinkiHelsinkiFinland
- Yugra State UniversityKhanty‐MansiyskRussia
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3
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Auvinen M, Kuula J, Grönholm T, Sühring M, Hellsten A. High-resolution large-eddy simulation of indoor turbulence and its effect on airborne transmission of respiratory pathogens-Model validation and infection probability analysis. Phys Fluids (1994) 2022; 34:015124. [PMID: 35340682 PMCID: PMC8939551 DOI: 10.1063/5.0076495] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/10/2021] [Indexed: 05/18/2023]
Abstract
High-resolution large-eddy simulation (LES) is exploited to study indoor air turbulence and its effect on the dispersion of respiratory virus-laden aerosols and subsequent transmission risks. The LES modeling is carried out with unprecedented accuracy and subsequent analysis with novel mathematical robustness. To substantiate the physical relevance of the LES model under realistic ventilation conditions, a set of experimental aerosol concentration measurements are carried out, and their results are used to successfully validate the LES model results. The obtained LES dispersion results are subjected to pathogen exposure and infection probability analysis in accordance with the Wells-Riley model, which is here mathematically extended to rely on LES-based space- and time-dependent concentration fields. The methodology is applied to assess two dissimilar approaches to reduce transmission risks: a strategy to augment the indoor ventilation capacity with portable air purifiers and a strategy to utilize partitioning by exploiting portable space dividers. The LES results show that use of air purifiers leads to greater reduction in absolute risks compared to the analytical Wells-Riley model, which fails to predict the original risk level. However, the two models do agree on the relative risk reduction. The spatial partitioning strategy is demonstrated to have an undesirable effect when employed without other measures, but may yield desirable outcomes with targeted air purifier units. The study highlights the importance of employing accurate indoor turbulence modeling when evaluating different risk-reduction strategies.
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Affiliation(s)
- Mikko Auvinen
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
- Author to whom correspondence should be addressed:
| | - Joel Kuula
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
| | - Tiia Grönholm
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
| | - Matthias Sühring
- Institute of Meteorology and Climatology, Leibniz University Hannover, Herrenhäuser Strasse 2, 30419 Hannover, Germany
| | - Antti Hellsten
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
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Grönholm T, Mäkelä T, Hatakka J, Jalkanen JP, Kuula J, Laurila T, Laakso L, Kukkonen J. Evaluation of Methane Emissions Originating from LNG Ships Based on the Measurements at a Remote Marine Station. Environ Sci Technol 2021; 55:13677-13686. [PMID: 34623135 PMCID: PMC8529869 DOI: 10.1021/acs.est.1c03293] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
We analyzed pollution plumes originating from ships using liquefied natural gas (LNG) as a fuel. Measurements were performed at a station located on the Utö island in the Baltic Sea during 2015-2021 when vessels passed the station along an adjacent shipping lane and the wind direction allowed the measurements. The ratio of the measured concentration peaks ΔCH4/ΔCO2 ranged from 1% to 9% and from 0.1% to 0.5% for low and high pressure dual fuel engines, respectively. The ratio of the measured concentration peaks of ΔNOx/ΔCO2 varied between 0.5‰ and 8.7‰, which was not explained by engine type. The results were consistent with previously measured on-board or test-bed values for the corresponding ratios of emissions. While the methane emissions from high pressure dual fuel engines were found to fulfill the goal of reducing the climatic impacts of shipping, the emissions originating from low pressure dual fuel engines were found to be substantially high, with a potential for increased climatic impacts compared with using traditional marine fuels. Taking only the global warming potential into account, we can suggest a limit value for the methane emissions; the ratio of the emissions ΔCH4/ΔCO2 originating from LNG powered ships should not exceed 1.4%.
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Affiliation(s)
- Tiia Grönholm
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Timo Mäkelä
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Juha Hatakka
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Jukka-Pekka Jalkanen
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Joel Kuula
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Tuomas Laurila
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
| | - Lauri Laakso
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
- School
of Physical and Chemical Sciences, North-West University, PB X6001, Potchefstroom, 2520, Republic of South Africa
| | - Jaakko Kukkonen
- Finnish
Meteorological Institute, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland
- Centre
for Atmospheric and Climate Physics Research and Centre for Climate
Change Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, United
Kingdom
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Vesala T, Sevanto S, Grönholm T, Salmon Y, Nikinmaa E, Hari P, Hölttä T. Effect of Leaf Water Potential on Internal Humidity and CO 2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure. Front Plant Sci 2017; 8:54. [PMID: 28220128 PMCID: PMC5292819 DOI: 10.3389/fpls.2017.00054] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 01/10/2017] [Indexed: 05/10/2023]
Abstract
The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO2, thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.
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Affiliation(s)
- Timo Vesala
- Department of Physics, University of HelsinkiHelsinki, Finland
- Department of Forest Sciences, University of HelsinkiHelsinki, Finland
- Viikki Plant Science Centre, University of HelsinkiHelsinki, Finland
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National LaboratoryLos Alamos, NM, USA
| | - Tiia Grönholm
- Department of Physics, University of HelsinkiHelsinki, Finland
| | - Yann Salmon
- Department of Physics, University of HelsinkiHelsinki, Finland
| | - Eero Nikinmaa
- Department of Forest Sciences, University of HelsinkiHelsinki, Finland
| | - Pertti Hari
- Department of Forest Sciences, University of HelsinkiHelsinki, Finland
| | - Teemu Hölttä
- Department of Forest Sciences, University of HelsinkiHelsinki, Finland
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Katul GG, Grönholm T, Launiainen S, Vesala T. Predicting the dry deposition of aerosol-sized particles using layer-resolved canopy and pipe flow analogy models: Role of turbophoresis. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jd012853] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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7
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Grönholm T, Launiainen S, Ahlm L, Mårtensson EM, Kulmala M, Vesala T, Nilsson ED. Aerosol particle dry deposition to canopy and forest floor measured by two-layer eddy covariance system. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jd010663] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Grönholm T, Haapanala S, Launiainen S, Rinne J, Vesala T, Rannik U. The dependence of the beta coefficient of REA system with dynamic deadband on atmospheric conditions. Environ Pollut 2008; 152:597-603. [PMID: 17825967 DOI: 10.1016/j.envpol.2007.06.071] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 06/20/2007] [Accepted: 06/29/2007] [Indexed: 05/17/2023]
Abstract
We simulated the REA system with dynamic deadband to study numerical value and the effect of atmospheric conditions on the empirical constant beta which relates vertical flux to concentration difference between updrafts and downdrafts. We found that the value of beta depends only weakly on the friction velocity and atmospheric stability. In agreement with previous studies, the median value obtained for a system with dynamic deadband proportional to 0.5 times the running mean of the standard deviation of vertical wind speed was beta=0.42+/-0.03. For a single half-hour measurement one has to consider the large uncertainty of +/-0.2. According to our study, the dynamic deadband enables the use of a constant value of beta in flux calculation.
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Affiliation(s)
- Tiia Grönholm
- Department of Physical Sciences, University of Helsinki, P.O. Box 64, FIN-00014, Finland.
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Abstract
Log-normal distributions describe data from diverse disciplines of science. However, the fundamental basis of log-normal distributions is unknown. We suggest that the skewed distributions are outcomes of natural processes i.e. they result from the principle of increasing entropy. Fluctuations during the course of evolution toward more probable states yield multiplicative variations about the mean. The non-linear dispersion of thermodynamic states, i.e. matter and energy defined by chemical potentials, underlies the skew. Cumulative curves of skewed distributions without integrable analytical forms are characteristic of natural processes.
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Affiliation(s)
- Tiia Grönholm
- Department of Physical Sciences, Institute of Biotechnology, FI-00014, University of Helsinki, Finland
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Pryor SC, Larsen SE, Sørensen LL, Barthelmie RJ, Grönholm T, Kulmala M, Launiainen S, Rannik Ü, Vesala T. Particle fluxes over forests: Analyses of flux methods and functional dependencies. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd008066] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sevanto S, Suni T, Pumpanen J, Grönholm T, Kolari P, Nikinmaa E, Hari P, Vesala T. Wintertime photosynthesis and water uptake in a boreal forest. Tree Physiol 2006; 26:749-57. [PMID: 16510390 DOI: 10.1093/treephys/26.6.749] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Warm air in combination with frozen soil is a major cause of wintertime drought damage in evergreen plants in subalpine and boreal environments. We analyzed diurnal tree stem diameter variation (SDV), which reflects soil water uptake, canopy-level water vapor flux (Fw), stand photosynthesis (Ps), photosynthetically active radiation (PAR), soil and air temperatures (Ts and T air, respectively) and soil liquid water content (theta) to determine under what conditions photosynthesis is possible in wintertime and how crucial water uptake from soil is for photosynthesis. Measurements were made under field conditions in a Scots pine forest in southern Finland during winter 2002-2003. We found four wintertime periods when there was measurable Ps and SDV, the latter always starting 2-7 days after photosynthesis and both usually ending on the same day. Stand photosynthesis began when T air reached 3-4 degrees C and ended when T air dropped below -7 degrees C. The trees appeared to rely on stored stem water first and started taking up water from the soil a few days later, when the transpirational demand became strong enough. The more difficult it was to access soil water because of low Ts or low theta, the longer the trees used water stored in their stems. Even partial stem freezing did not prevent photosynthesis or soil water uptake.
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Affiliation(s)
- Sanna Sevanto
- Department of Physical Sciences, P.O. Box 64, 00014 University of Helsinki, Finland.
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Bäcklund T, Palojoki E, Grönholm T, Eriksson A, Vuolteenaho O, Laine M, Tikkanen I. Dual inhibition of angiotensin converting enzyme and neutral endopeptidase by omapatrilat in rat in vivo. Pharmacol Res 2001; 44:411-8. [PMID: 11712872 DOI: 10.1006/phrs.2001.0875] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pharmacological profile of a vasopeptidase inhibitor is dependent on the ratio of neutral endopeptidase (NEP)vs angiotensin converting enzyme (ACE) inhibition of the particular drug. We used in vitro autoradiography to determine the local renal and cardiac NEP and ACE inhibition after oral treatment with the dual NEP/ACE inhibitor omapatrilat in rat. Maximal inhibition of both renal NEP and ACE was achieved at the omapatrilat dose of 40 mg kg(-1)day(-1). Effective local ACE inhibition was detected also in the myocardium. The haemodynamic effects were similar to captopril, but omapatrilat treatment produced more favorable effect on natriuretic peptide levels. In conclusion, good tissue penetration of omapatrilat and balanced NEP/ACE inhibition may prove to be useful in the treatment of hypertension and heart failure.
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Affiliation(s)
- T Bäcklund
- Department of Medicine, Helsinki University Central Hospital and Minerva Foundation Institute for Medical Research, Helsinki, Finland
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13
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Aaltonen P, Luimula P, Aström E, Palmen T, Grönholm T, Palojoki E, Jaakkola I, Ahola H, Tikkanen I, Holthöfer H. Changes in the expression of nephrin gene and protein in experimental diabetic nephropathy. J Transl Med 2001; 81:1185-90. [PMID: 11555666 DOI: 10.1038/labinvest.3780332] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [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] Open
Abstract
Diabetic nephropathy is a major complication of diabetes leading to thickening of the glomerular basement membrane, glomerular hypertrophy, mesangial expansion, and overt renal disease. The pathophysiologic mechanisms of diabetic nephropathy remain poorly understood. Nephrin is a recently found podocyte protein crucial for the interpodocyte slit membrane structure and maintenance of an intact filtration barrier. Here we have assessed the role of nephrin in two widely used animal models of diabetes, the streptozotocin model of the rat and the nonobese diabetic mouse. In both models, the expression levels of nephrin-specific mRNA as determined by real-time quantitative polymerase chain reaction increased up to two-fold during several weeks of follow-up. Immunohistochemical stainings revealed nephrin also more centrally within the glomerular tuft along with its preferential site in podocytes. Interestingly, as detected by immunoblotting, nephrin protein was also found in the urine of streptozotocin-induced rats. We conclude that nephrin is connected to the early changes of diabetic nephropathy and thus may contribute to the loss of glomerular filtration function.
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Affiliation(s)
- P Aaltonen
- Haartman Institute, Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland
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