Search Results
Results 201 - 250 of 928
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Ohlson M - - 2001
The effect of shape on the transglomerular passage of solutes has not been hitherto systematically studied. We perfused isolated rat kidneys to determine the fractional clearances (theta) at various filtration rates for four molecules of different shapes but with similar Stokes-Einstein radii (aSE = 34-36 A). The theta for hyaluronan, ...
Gallego B - - 2001
The purpose of this study was to evaluate the functional and structural renal damage observed in aortic-constricted hypertensive rats and to identify their possible relationship with transforming growth factor beta (TGF-beta) expression. Progressive renovascular hypertension was induced by progressive aortic constriction between the two renal arteries. Three months after constriction, ...
Bentzer P - - 2001
The capillary filtration coefficient (CFC) is assumed to reflect both microvascular hydraulic conductivity and the number of perfused capillaries at a given moment (precapillary sphincter activity). Estimation of hydraulic conductivity in vivo with the CFC method has therefore been performed under conditions of unchanged vascular tone and metabolic influence. There ...
Holstein-Rathlou Niels-Henrik - - 2001
Experimental data for tubular pressure oscillations in rat kidneys are analyzed in order to examine the different types of synchronization that can arise between neighboring functional units. For rats with normal blood pressure, the individual unit (the nephron) typically exhibits regular oscillations in its tubular pressure and flow variations. For ...
Guidi E - - 2001
Familial hypertension, glomerular hemodynamic alterations, and dysregulation of tubulo-glomerular feedback (TGFB) have all been associated with the development of chronic renal failure. In the present study we evaluated renal and glomerular hemodynamics and TGFB responses in healthy kidney donors either with or without familial hypertension, before and after nephrectomy. Para-amino-hippurate ...
Denton K M - - 2001
OBJECTIVE: To determine the effects on pre- and post-glomerular vascular resistance of adrenocorticotrophin (ACTH)-induced hypertension in rats, before and after blockade of nitric oxide formation. DESIGN: Four groups of Sprague-Dawley rats were studied. Measurements were made in ACTH- (Synacthen Depot, 0.25 mg/kg twice daily for 8 days) and sham-treated anaesthetized ...
Tiller F M - - 2001
In accord with Darcy's law, the flow rate through a porous bed depends upon the pressure drop deltap(c). In general, increasing deltap(c) leads to increased values of flow rate and average percentage solids in filtration operations. When cakes become super-compactible, their behavior undergoes an unexpected change in which both the ...
Oyanagi-Tanaka Y - - 2001
BACKGROUND: Blood flow in the microvasculature plays a pivotal role in determining the outcome of injury and repair in inflamed tissue. Real-time observation of the kidney microvasculature, including the glomerular capillary tufts, is extremely difficult because of the methodological limitations of currently available microscope optics. In the present study, we ...
Hu X - - 2000
We tested the hypothesis that the effective oncotic force that opposes fluid filtration across the microvessel wall is the local oncotic pressure difference across the endothelial surface glycocalyx and not the global difference between the plasma and tissue. In single frog mesenteric microvessels perfused and superfused with solutions containing 50 ...
Mäkelä S - - 2000
BACKGROUND: Nephropathia epidemica (NE) is a mild form of hemorrhagic fever with renal syndrome caused by Puumala hantavirus. Its long-term prognosis is considered favorable. Some reports suggest, however, that a previous hantavirus infection increases the risk of hypertension. METHODS: We studied 46 previously healthy subjects (26 males and 20 females, ...
Ishimitsu T - - 2000
Plasma albumin leaks into urine as a result of glomerular hypertension and basement membrane injury, while urinary type IV collagen derives from mesangial matrix and glomerular basement membrane. The purpose of this study was to elucidate the pathophysiological significance of these urinary microproteins as an indicator of cardiovascular organ injuries ...
Barnidge J - - 2000
OBJECTIVE: The purpose of this study was to determine whether the leukocyte chemoattractant N-formyl methionyl-leucyl-phenylalanine (FMLP) increases capillary fluid filtration rate (Jv/S), and if so, to determine whether the mechanism involves arteriovenular communication. METHODS: Intravital microscopy was used in the rat mesentery to measure capillary Jv/S by a micro-occlusion technique. ...
Ben-Nun J - - 2000
PURPOSE: To study the effect of acute hyperglycemia on the erythrocyte flow in specific retinal capillary paths. METHODS: A technique for fluorescent labeling of a known fraction of the erythrocyte moiety of systemic blood was combined with fluorescence viewing of the retinal capillary network in live cats. This technique was ...
Lopes de Faria J M - - 2000
PURPOSE: To investigate whether elevated erythrocyte Na+/Li+ countertransport (Na+/Li+ CT) activity is present in patients with proliferative diabetic retinopathy (PDR). METHODS: The rate of Na+/Li+ CT activity assayed in 21 patients with type 1 diabetes mellitus (DM) presenting PDR was compared with 10 patients with nonproliferative retinopathy (NPDR) and with ...
Harrap S B - - 2000
Abnormal renovascular resistance and glomerular filtration rate are characteristic of established hypertension and may also be involved in its pathogenesis. To determine renal and body fluid correlates of the predisposition to high blood pressure, we examined 100 healthy young adults with high or low blood pressure. Within each group, half ...
Hancock T V - - 2000
Whole-body and organ-level transcapillary filtration rates and coefficients are virtually unexamined in ectothermal vertebrates. These filtration rates appear to be greater than in mammals when plasma volume shifts and lymphatic function are analyzed. Gravimetric techniques monitoring whole-body mass changes were used to estimate net systemic filtration in Bufo marinus and ...
Nosadini R - - 2000
Heterogeneity in renal structure has been described in type 2 diabetic patients with both microalbuminuria and proteinuria; in fact, only a subset of type 2 diabetic patients have the typical diabetic glomerulopathy. However, it is currently unknown whether abnormalities in albumin excretion rate (AER) have a different renal prognostic value ...
Kotchen T A - - 2000
The incidence of end-stage renal disease attributable to hypertension is 5-fold greater in African Americans than in whites. To determine whether glomerular hyperfiltration is an antecedent to renal failure, we compared responses of renal blood flow and glomerular filtration rate to graded infusions of norepinephrine (0. 01, 0.025, and 0.05 ...
Magyar C E - - 2000
Acute hypertension provokes a rapid decrease in proximal tubule salt and water reabsorption that increases the levels of sodium chloride at the macula densa, the error signal to increase arteriolar resistance to autoregulate renal blood flow and glomerular filtration rate, and contributes to pressure natriuresis. The molecular mechanisms responsible for ...
Hellmann H - - 2000
The involvement of the kidney in the pathogenesis of hypertension has long been recognised, although the specific renal mechanisms underlying this phenomenon are still unknown. A current hypothesis attributes hypertension to a reduction in glomerular filtration area by glomerular loss. The present study analyses the relationship between glomerular number and ...
Persson A E - - 2000
The juxtaglomerular apparatus (JGA) has the very important functions of detecting the fluid flow rate to the distal tubule and thus controlling the glomerular filtration rate (GFR) (tubuloglomerular feedback mechanism [TGF]) and renin release from the afferent arteriole. In studies of the TGF it has been evident that the sensitivity ...
Konishi Y - - 2000
OBJECTIVE: Studies of experimental animals show glomerular hypertension to be important in the progression of glomerular disease. We evaluated this connection clinically by examining the relationship between glomerular hemodynamics and histological changes in patients with immunoglobulin (Ig)A nephropathy. METHODS: The subjects were 23 patients with IgA nephropathy. All patients underwent ...
Schnermann J - - 2000
The role of thromboxane (TP) in the vasoconstriction induced by tubuloglomerular feedback or 18-h ureteral obstruction was studied in wild type mice (TP +/+), and in heterozygous (TP +/-) and homozygous TP receptor knockout mice (TPR -/-). TGF function was assessed from the response of stop flow pressure (PSF) to ...
Forman M F - - 1999
During the pathophysiological progression of pulmonary hypertension syndrome (PHS; ascites), broilers concurrently develop systemic hypotension (low mean systemic arterial pressure) that may initiate renal retention of water and solute, contributing to fluid accumulation in the abdominal cavity (ascites). In male Single Comb White Leghorns, glomerular filtration is autoregulated over a ...
Weir M R - - 1999
Diabetes and hypertension are the leading causes of end-stage renal disease in the Western world. Inadequate control of both systemic and glomerular capillary pressure in diabetics results in increasing hydraulic force and mechanical stretch on the glomeruli, with a subsequent increase in proteinuria and ultimately glomerulosclerosis. Therapeutic strategies that combine ...
Evensen H T - - 1999
A technique has been developed for high lane density loading of small-volume DNA samples in a horizontal agarose gel. This technique has been investigated with a simple hand-held tool that is made to couple to sample output from a new capillary-based sample automation system. The approach consists of piercing the ...
Okada N - - 1999
A method for the clinical assessment of glomerular hemodynamics has been published previously. We here examined whether, when using this method, renal creatinine clearance (Ccr) can be substituted for the glomerular filtration rate (GFR). The study subjects comprised 57 inpatients from Osaka City General Hospital: 30 with type 2 diabetes ...
Christensen P K - - 1999
BACKGROUND: The ability of the kidney to maintain constancy of the glomerular filtration rate (GFR) over a wide range of renal perfusion pressures is termed autoregulation. Defective autoregulation of GFR has been demonstrated in diabetic nephropathy. Whether this is also the case in patients with nondiabetic nephropathies is not known. ...
Kawabata M - - 1999
1. To obtain some insight into the renoprotective mechanism of the new calcium antagonist efonidipine hydrochloride, we evaluated the acute effects of efonidipine on proteinuria, glomerular haemodynamics and the tubuloglomerular feedback (TGF) mechanism in anaesthetized 24-25-week-old spontaneously hypertensive rats (SHR) with glomerular injury. 2. Efonidipine infusion at 10 micrograms/kg per ...
Willinger M - - 1999
Because of the closed plasma (secondary) circuit in the Microspheres based Detoxification System (MDS), a convective blood purification system, the same amount of filtrated plasma is backfiltrated into the blood circuit. Therefore, there is no direct way to determine the ultrafiltrate production rate, which is an important factor of efficiency. ...
Imanishi M - - 1999
AIMS/HYPOTHESIS: Results from animal models of glomerular hypertension have suggested that this disorder is one cause of albuminuria in diabetic nephropathy. We evaluated this hypothesis clinically. METHODS: The subjects were 20 patients with Type II (non-insulin-dependent) diabetes mellitus but without uraemia or hypertension: 8 had normoalbuminuria and 12 had albuminuria ...
Kato H - - 1999
In glomerular hypertension, mesangial cells (MC) are subjected to at least two physical forces: mechanical stretch and high transmural pressure. Increased transmural pressure, as well as mechanical stretch, promotes MC proliferation, which may enhance glomerulosclerosis. The exact mechanism of this effect is not fully understood. We examined the effects of ...
Fauvel J P - - 1999
Rilmenidine is an imidazoline I1-receptor agonist that centrally acts by reducing the sympathetic tone. There is strong experimental evidence that natriuresis could be evoked by proximal tubular I1-receptors that have also been isolated in human kidneys. However, in humans, the natriuretic effects of proximal tubular I1-receptors have never been demonstrated. ...
Smit J J - - 1999
BACKGROUND: Leukocyte filtration of systemic blood during cardiopulmonary bypass surgery to reduce post-operative morbidity has not yet been established because of the enormous leukocyte release from the third space. This study was designed to examine the efficiency and safety of leukocyte filtration by a new prototype large capacity leukocyte filter. ...
Cortes P - - 1999
Due to their elasticity, glomeruli will undergo excessive expansion and repetitive cycles of distension contraction under conditions of impaired glomerular pressure autoregulation and systemic arterial hypertension. These alterations in glomerular volume are associated with mesangial cell stretch which in turn stimulates the synthesis and deposition of ECM with eventual mesangial ...
Kobayashi M - - 1999
To characterize the configuration of "tunnel capillaries" in myocytes, an ultrastructural three-dimensional (3-D) study was performed on pressure-overloaded rat hearts induced by 16-week constriction of the ascending aorta. The hearts showed high incidence (6.1 +/- 3.6%) of tunnel capillary formation. Eighty-two myocytes (26.4%) had tunnel capillaries in a cubic block ...
Bangstad H J - - 1999
OBJECTIVE: To investigate whether the degree of glomerular structural lesions in young patients with type 1 diabetes and microalbuminuria was associated with urinary albumin excretion rate (AER) 6 years later and whether the AER level was influenced by blood glucose control, blood pressure, or glomerular filtration rate (GFR). RESEARCH DESIGN ...
Burlet A - - 1999
We performed renal function tests in 18 young patients, 1.8-14.6 years of age, with cyanotic congenital heart disease (CCHD). Glomerular filtration rate was normal (116 +/- 4.5 ml/min/1.73 m2), and renal plasma flow was decreased (410 +/- 25 ml/min/1.73 m2) with a rise in the filtration fraction (29 +/- 1.1%). ...
Fine L G - - 1999
British contributions to renal physiology trace back to the seminal contribution of William Bowman, who defined the structure of mammalian nephron and its blood supply and pointed out its likely mode of function. A series of contributions followed, which stemmed from a distinguished lineage of physiologists based at University College ...
Watenpaugh D E - - 1998
BACKGROUND: Net whole-body transcapillary fluid transport (TFT) between the circulation and the interstitial (extravascular) space may be calculated as: IV - deltaPV - UV - IL, where IV=infused or ingested volume (when applicable), deltaPV = change in plasma volume, UV=urine volume, and IL=insensible loss. RESULTS: Infusion of 30 mL/kg isotonic ...
Lafayette R A - - 1998
BACKGROUND: Pre-eclampsia is characterized by hypertension, proteinuria and edema. Simultaneous studies of kidney function and structure have not been reported. We wished to explore the degree and nature of glomerular dysfunction in pre-eclampsia. METHODS: Physiologic techniques were used to estimate glomerular filtration rate (GFR), renal plasma flow and afferent oncotic ...
Lewis D M - - 1998
BACKGROUND: Peripheral edema, in combination with severe proteinuria and low serum albumin levels, is pathognomonic of the nephrotic syndrome, yet the exact mechanism of its formation is unknown. Two of the most important of the factors in Starling's forces controlling fluid filtration across the capillary have hitherto not been studied ...
Cavarape A - - 1998
OBJECTIVE: To assess the site of action of endothelin-1 in vessels of different sizes in the kidney in vivo and investigate the function of endothelin A (ET(A)) receptors in mediating renal and systemic vasoconstriction. DESIGN: The luminal diameters of different vessels were measured and glomerular blood flow in cortical glomeruli ...
Carlsson P O - - 1998
The aim of the present study was to measure capillary blood pressure and interstitial pressure in transplanted pancreatic islets and to correlate these measurements to capillary and tubular pressures in the adjacent kidney. For this purpose, 250 syngeneic islets were implanted under the renal capsule of WF rats and studied ...
Kongstad L - - 1998
Measuring the capillary filtration coefficient (CFC) from the transvascular fluid filtration following a fixed increase in transcapillary hydrostatic pressure is a common method to estimate capillary hydraulic permeability (conductivity) in an organ. Constant flow pump perfusion with an artificial perfusate and a maximally dilated vascular bed are often used in ...
Ronco C - - 1998
BACKGROUND: Hemodialysis using high flux membranes today is a commonly used therapy. The primary advantage is the larger spectrum of molecules removed with these membranes, and the mechanism of removal is in part due to a phenomenon of filtration and backfiltration along the length of the hollow fibers. We hypothesized ...
Cao P - - 1998
Pressure assisting and pressure programming the inlet of the capillary electrophoresis instrument were used for the analysis of peptide mixtures and protein digests using capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS). CE/ESI-MS of peptide mixtures and tryptic digests of proteins was studied using three different types of capillary columns: (i) a freshly ...
Smith A C - - 1998
BACKGROUND: Calcium channel blockers (CCBs) are known to have differential effects on both changes in proteinuria as well as progression of diabetic nephropathy. No clinical study, however, has evaluated whether the differential antiproteinuric effects of CCBs may be explained by their effect on glomerular membrane permeability. We, therefore, tested the ...
Mahy I R - - 1998
Capillary filtration coefficient is a critical determinant of fluid flux across the microvascular wall. Changes in capillary filtration coefficient have been described in a number of disease processes. Measurement is typically made by venous occlusion plethysmography using either the upper or lower limb, but a variety of measurement protocols have ...
Ogborn M R - - 1998
We undertook a case-control study to evaluate the renal health of survivors of hemolytic-uremic syndrome (HUS) from the 1991 Arctic epidemic of Escherichia coli O157:H7 gastroenteritis 4 years after the epidemic. Eighteen children who developed HUS during the 1991 epidemic and 18 age- and sex-matched controls from the same community ...
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