The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Bernard M. Churchill - One of the best experts on this subject based on the ideXlab platform.
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Intrarenal Resistive Index Correlates with Renal Pelvis Pressure
The Journal of Urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, Peter Chait, Bernard M. ChurchillAbstract:AbstractElevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure.Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14cm. water as the probable threshold for functionally normal collecting system pressure, it was found th...
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Intrarenal resistive index correlates with renal pelvis pressure.
The Journal of urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, P G Chait, Bernard M. ChurchillAbstract:Elevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure. Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14 cm. water as the probable threshold for functionally normal collecting system pressure, it was found that all Intrarenal indexes of 82% or less corresponded to renal pelvis pressures of less than 14 cm. water, while all of those greater than 82% corresponded to renal pelvis pressures greater than 14 cm. water. By combining several lines of evidence, it appears probable that as maximal diuresis induced by physiological and pharmacological means leads to acute transient elevation in renal pelvis pressure in a functionally obstructed collecting system, the Intrarenal resistive index is capable of reflecting this dynamic elevation in renal pelvis pressure and potentially able to distinguish physiologically significant upper urinary tract obstruction from nonobstructive dilatation.
Hiroyuki Kobori - One of the best experts on this subject based on the ideXlab platform.
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Independent regulation of renin–angiotensin–aldosterone system in the kidney
Clinical and Experimental Nephrology, 2018Co-Authors: Akira Nishiyama, Hiroyuki KoboriAbstract:Renin–angiotensin–aldosterone system (RAAS) plays important roles in regulating renal hemodynamics and functions, as well as in the pathophysiology of hypertension and renal disease. In the kidney, angiotensin II (Ang II) production is controlled by independent multiple mechanisms. Ang II is compartmentalized in the renal interstitial fluid with much higher concentrations than those existing in the circulation. Inappropriate activation of the Intrarenal RAAS is an important contributor to the pathogenesis of hypertension and renal injury. It has been revealed that Intrarenal Ang II levels are predominantly regulated by angiotensinogen and therefore, urinary angiotensinogen could be a biomarker for Intrarenal Ang II generation. In addition, recent studies have demonstrated that aldosterone contributes to the progression of renal injury via direct actions on glomerular podocytes, mesangial cells, proximal tubular cells and tubulo-interstitial fibroblasts through the activation of locally expressed mineralocorticoid receptor. Thus, it now appears that Intrarenal RAAS is independently regulated and its inappropriate activation contributes to the pathogenesis of the development of hypertension and renal disease. This short review article will focus on the independent regulation of the Intrarenal RAAS with an emphasis on the specific role of angiotensinogen.
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augmented Intrarenal and urinary angiotensinogen in hypertension and chronic kidney disease
Pflügers Archiv: European Journal of Physiology, 2012Co-Authors: Hiroyuki Kobori, Maki UrushiharaAbstract:Activated Intrarenal renin–angiotensin system plays a cardinal role in the pathogenesis of hypertension and chronic kidney disease. Angiotensinogen is the only known substrate for renin, which is the rate-limiting enzyme of the renin–angiotensin system. Because the levels of angiotensinogen are close to the Michaelis–Menten constant values for renin, angiotensinogen levels as well as renin levels can control the renin–angiotensin system activity, and thus, upregulation of angiotensinogen leads to an increase in the angiotensin II levels and ultimately increases blood pressure. Recent studies using experimental animal models have documented the involvement of angiotensinogen in the Intrarenal renin–angiotensin system activation and development of hypertension. Enhanced Intrarenal angiotensinogen mRNA and/or protein levels were observed in experimental models of hypertension and chronic kidney disease, supporting the important roles of angiotensinogen in the development and the progression of hypertension and chronic kidney disease. Urinary excretion rates of angiotensinogen provide a specific index of the Intrarenal renin–angiotensin system status in angiotensin II-infused rats. Also, a direct quantitative method has been developed recently to measure urinary angiotensinogen using human angiotensinogen enzyme-linked immunosorbent assay. These data prompted us to measure urinary angiotensinogen in patients with hypertension and chronic kidney disease, and investigate correlations with clinical parameters. This short article will focus on the role of the augmented Intrarenal angiotensinogen in the pathophysiology of hypertension and chronic kidney disease. In addition, the potential of urinary angiotensinogen as a novel biomarker of the Intrarenal renin–angiotensin system status in hypertension and chronic kidney disease will be also discussed.
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the Intrarenal renin angiotensin system from physiology to the pathobiology of hypertension and kidney disease
Pharmacological Reviews, 2007Co-Authors: Hiroyuki Kobori, Gabriel L Navar, Masaomi Nangaku, Akira NishiyamaAbstract:In recent years, the focus of interest on the role of the renin-angiotensin system (RAS) in the pathophysiology of hypertension and organ injury has changed to a major emphasis on the role of the local RAS in specific tissues. In the kidney, all of the RAS components are present and Intrarenal angiotensin II (Ang II) is formed by independent multiple mechanisms. Proximal tubular angiotensinogen, collecting duct renin, and tubular angiotensin II type 1 (AT1) receptors are positively augmented by Intrarenal Ang II. In addition to the classic RAS pathways, prorenin receptors and chymase are also involved in local Ang II formation in the kidney. Moreover, circulating Ang II is actively internalized into proximal tubular cells by AT1 receptor-dependent mechanisms. Consequently, Ang II is compartmentalized in the renal interstitial fluid and the proximal tubular compartments with much higher concentrations than those existing in the circulation. Recent evidence has also revealed that inappropriate activation of the Intrarenal RAS is an important contributor to the pathogenesis of hypertension and renal injury. Thus, it is necessary to understand the mechanisms responsible for independent regulation of the Intrarenal RAS. In this review, we will briefly summarize our current understanding of independent regulation of the Intrarenal RAS and discuss how inappropriate activation of this system contributes to the development and maintenance of hypertension and renal injury. We will also discuss the impact of antihypertensive agents in preventing the progressive increases in the Intrarenal RAS during the development of hypertension and renal injury.
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kidney specific enhancement of ang ii stimulates endogenous Intrarenal angiotensinogen in gene targeted mice
American Journal of Physiology-renal Physiology, 2007Co-Authors: Hiroyuki Kobori, Naro Ohashi, Yuri Ozawa, Ryousuke Satou, Akemi Katsurada, Kayoko Miyata, Naoki Hase, Yuki Suzaki, Curt D Sigmund, Gabriel L NavarAbstract:This study was performed in transgenic mice to test the hypothesis that the selective Intrarenal overproduction of ANG II increases Intrarenal mouse (m) angiotensinogen (AGT) expression. We used th...
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Intrarenal angiotensin II and hypertension
Current hypertension reports, 2003Co-Authors: L. Gabriel Navar, Hiroyuki Kobori, Minolfa C. Prieto-carrasqueroAbstract:Elevations in Intrarenal angiotensin II (Ang II) cause reductions in renal function and sodium excretion that contribute to progressive hypertension and lead to renal and vascular injury. Augmentation of Intrarenal Ang II occurs by several processes, leading to levels much greater than can be explained from the circulating levels. In Ang II-dependent hypertension, Ang II is internalized via an AT1 receptor mechanism, but there is also sustained Intrarenal production of Ang II. Ang II exerts a positive feedback action on Intrarenal angiotensinogen (AGT) mRNA and protein. The increased Intrarenal AGT production is associated with increased Intrarenal and intracellular Ang II contents and urinary AGT excretion rates. The increased urinary AGT indicates spillover of AGT into distal nephron segments supporting enhanced distal Ang II formation and sodium reabsorption. The augmentation of Intrarenal Ang II provides the basis for sustained actions on renal function, sodium excretion, and maintenance of hypertension.
Leo C.t. Fung - One of the best experts on this subject based on the ideXlab platform.
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Intrarenal Resistive Index Correlates with Renal Pelvis Pressure
The Journal of Urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, Peter Chait, Bernard M. ChurchillAbstract:AbstractElevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure.Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14cm. water as the probable threshold for functionally normal collecting system pressure, it was found th...
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Intrarenal resistive index correlates with renal pelvis pressure.
The Journal of urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, P G Chait, Bernard M. ChurchillAbstract:Elevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure. Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14 cm. water as the probable threshold for functionally normal collecting system pressure, it was found that all Intrarenal indexes of 82% or less corresponded to renal pelvis pressures of less than 14 cm. water, while all of those greater than 82% corresponded to renal pelvis pressures greater than 14 cm. water. By combining several lines of evidence, it appears probable that as maximal diuresis induced by physiological and pharmacological means leads to acute transient elevation in renal pelvis pressure in a functionally obstructed collecting system, the Intrarenal resistive index is capable of reflecting this dynamic elevation in renal pelvis pressure and potentially able to distinguish physiologically significant upper urinary tract obstruction from nonobstructive dilatation.
Gordon A. Mclorie - One of the best experts on this subject based on the ideXlab platform.
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Intrarenal Resistive Index Correlates with Renal Pelvis Pressure
The Journal of Urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, Peter Chait, Bernard M. ChurchillAbstract:AbstractElevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure.Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14cm. water as the probable threshold for functionally normal collecting system pressure, it was found th...
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Intrarenal resistive index correlates with renal pelvis pressure.
The Journal of urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, P G Chait, Bernard M. ChurchillAbstract:Elevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure. Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14 cm. water as the probable threshold for functionally normal collecting system pressure, it was found that all Intrarenal indexes of 82% or less corresponded to renal pelvis pressures of less than 14 cm. water, while all of those greater than 82% corresponded to renal pelvis pressures greater than 14 cm. water. By combining several lines of evidence, it appears probable that as maximal diuresis induced by physiological and pharmacological means leads to acute transient elevation in renal pelvis pressure in a functionally obstructed collecting system, the Intrarenal resistive index is capable of reflecting this dynamic elevation in renal pelvis pressure and potentially able to distinguish physiologically significant upper urinary tract obstruction from nonobstructive dilatation.
Antoine E. Khoury - One of the best experts on this subject based on the ideXlab platform.
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Intrarenal Resistive Index Correlates with Renal Pelvis Pressure
The Journal of Urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, Peter Chait, Bernard M. ChurchillAbstract:AbstractElevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure.Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14cm. water as the probable threshold for functionally normal collecting system pressure, it was found th...
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Intrarenal resistive index correlates with renal pelvis pressure.
The Journal of urology, 1994Co-Authors: Leo C.t. Fung, Robert E. Steckler, Antoine E. Khoury, Gordon A. Mclorie, P G Chait, Bernard M. ChurchillAbstract:Elevation in the Intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the Intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between Intrarenal resistive index and collecting system pressure. Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study Intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14 cm. water as the probable threshold for functionally normal collecting system pressure, it was found that all Intrarenal indexes of 82% or less corresponded to renal pelvis pressures of less than 14 cm. water, while all of those greater than 82% corresponded to renal pelvis pressures greater than 14 cm. water. By combining several lines of evidence, it appears probable that as maximal diuresis induced by physiological and pharmacological means leads to acute transient elevation in renal pelvis pressure in a functionally obstructed collecting system, the Intrarenal resistive index is capable of reflecting this dynamic elevation in renal pelvis pressure and potentially able to distinguish physiologically significant upper urinary tract obstruction from nonobstructive dilatation.