Mechanisms of progressive glomerular injury in membranous nephropathy.

1998 ◽  
Vol 9 (8) ◽  
pp. 1389-1398
Author(s):  
A Squarer ◽  
K V Lemley ◽  
S Ambalavanan ◽  
B Kristal ◽  
W M Deen ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Surface Area ◽  
Membranous Nephropathy ◽  
Significant Loss ◽  
Repeat Biopsy ◽  
Hydraulic Permeability ◽  
Glomerular Injury ◽  
Ultrafiltration Pressure ◽  
Global Glomerulosclerosis ◽  
Filtration Surface

Glomerular function and structure were serially evaluated in 15 patients with membranous nephropathy who exhibited relapsing nephrosis and chronic depression of GFR. GFR declined from 56+/-8 (mean+/-SEM) at onset to 31+/-4 ml/min per 1.73 m2 after a 2- to 5-yr period of observation (P < 0.05). An analysis of filtration dynamics suggested persistent elevation of net ultrafiltration pressure. To examine a possible role for declining intrinsic glomerular filtration capacity as the basis for the observed hypofiltration, glomeruli in the baseline and a repeat biopsy (performed after a median of 28 mo) were subjected to morphometric analysis and mathematical modeling. Analysis of the baseline biopsy revealed a reduction in filtration slit frequency and thickening of the glomerular basement membrane, lowering computed hydraulic permeability by 66% compared with normal kidney donors. In contrast, filtration surface area was increased by 37% as a result of glomerular hypertrophy. The repeat biopsy revealed persistent depression of hydraulic permeability, primarily owing to foot process broadening. An additional finding was a decrease in filtration surface area from baseline in patent glomeruli, possibly due to encroachment on the capillary lumen of an increasingly widened basement membrane. Also, a striking increase in the prevalence of global glomerulosclerosis from 7+/-2% to 23+/-4% was found between the two biopsies, suggesting a significant loss of functioning nephrons. It is concluded that hypofiltration in membranous nephropathy is the consequence of a biphasic loss of glomerular ultrafiltration capacity, initially owing to impaired hydraulic permeability that is later exacerbated by a superimposed loss of functioning glomeruli and of filtration surface area.

Derecruitment of filtration surface area in paraquat-injured isolated dog lungs

1990 ◽  
Vol 68 (4) ◽  
pp. 1581-1589 ◽  
Author(s):  
T. Shibamoto ◽  
J. C. Parker ◽  
A. E. Taylor ◽  
M. I. Townsley
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Vascular Resistance ◽  
High Flow ◽  
Base Line ◽  
Flow Rates ◽  
Blood Flows ◽  
Capillary Filtration Coefficient ◽  
Specific Index ◽  
Filtration Surface

The capillary filtration coefficient (Kf,c) is a sensitive and specific index of vascular permeability if surface area remains constant, but derecruitment might affect Kf,c in severely damaged lungs with high vascular resistance. We studied the effect of high and low blood flow rates on Kf,c in papaverine-pretreated blood-perfused isolated dog lungs perfused under zone 3 conditions with and without paraquat (PQ, 10(-2) M). Three Kf,cs were measured successively at hourly intervals for 5 h. These progressed sequentially from isogravimetric blood flow with low vascular pressure (I/L) to high flow with low vascular pressure (H/L) to high flow with high vascular pressure (H/H). The blood flows of H/L and H/H were greater than or equal to 1.5 times that of I/L. There were no significant changes in Kf,c in lungs without paraquat over a 50-fold range of blood flow rates. At 3 h after PQ, I/L-Kf,c was significantly increased and both isogravimetric capillary pressure and total protein reflection coefficient were decreased from base line. At 4 and 5 h, H/L-Kf,c was significantly greater than the corresponding I/L-Kf,c (1.01 +/- 0.22 vs. 0.69 +/- 0.09 and 1.26 +/- 0.19 vs. 0.79 +/- 0.10 ml.min-1.cmH2O-1.100 g-1, respectively) and isogravimetric blood flow decreased to 32.0 and 12.0% of base line, respectively. Pulmonary vascular resistance increased to 12 times base line at 5 h after PQ. We conclude that Kf,c is independent of blood flow in uninjured lungs. However, Kf,c measured at isogravimetric blood flow underestimated the degree of increase in Kf,c in severely damaged and edematous lungs because of a high vascular resistance and derecruitment of filtering surface area.

Characteristics of variably saturated granular bentonite after long-term storage at near-field relevant temperatures

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 343-361 ◽  
Author(s):  
M. Valter ◽  
M. Plötze
Keyword(s):  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
Elevated Temperatures ◽  
Near Field ◽  
Exchange Capacity ◽  
Hydraulic Permeability ◽  
Cation Composition ◽  
Retention Capacity

AbstractBentonite is a potential material for use in the engineered barrier of radioactive waste repositories because of its low hydraulic permeability, self-sealing capability and retention capacity. It is expected that bentonite would react at the elevated temperatures accompanying the radioactive decay in the nuclear waste. The presented study was started in order to improve understanding of the coupled influence of temperature and (pore) water on the physicochemical and mineralogical properties of bentonite during thermal treatment under near-field relevant conditions. Granular Na-bentonite MX-80 was differently saturated (Sr = 1–0.05) and stored at different temperatures (50–150°C) in a closed system. Upon dismantling after different periods of time (3 to 18 months), mineralogical characteristics, cation exchange capacity and content of leachable cations, as well as physicochemical properties such as surface area and water adsorption were investigated.The results showed a high mineralogical stability. A slight conversion from the sodium to an earth alkali form of the bentonite was observed. However, considerable changes in the physicochemical properties of the bentonite were observed, particularly by treatment above the critical temperature of 120°C. The cation exchange capacity decreased during heating at 150°C by approximately. 10%. The specific surface area dropped by more than 50%. The water uptake capacity under free swelling conditions showed a slight tendency to lower values especially for samples heated for more than 12 months. The water vapour adsorption ability in contrast drops by 25% already within three months at T = 120°C. These changes are mostly related to the variations in the interlayer cation composition and to smectite aggregation processes. The observed alterations are rather subtle. However, temperatures ⩾ 120°C had a remarkable negative influence on different properties of MX-80.

Membranous nephropathy

2010 ◽  
pp. 3985-3988
Author(s):  
Dwomoa Adu
Keyword(s):  
Prostate Cancer ◽  
Systemic Lupus Erythematosus ◽  
Nephrotic Syndrome ◽  
Basement Membrane ◽  
Autoimmune Diseases ◽  
Outer Surface ◽  
Glomerular Basement Membrane ◽  
Lupus Erythematosus ◽  
Membranous Nephropathy ◽  
Systemic Lupus

Membranous nephropathy, which accounts for 20 to 30% of cases of the nephrotic syndrome in adults, is defined histologically by the presence of subepithelial immune deposits on the outer surface of the glomerular basement membrane. The immune mechanisms that lead to this are uncertain, and most cases are of unknown cause (idiopathic), but the condition can be associated with autoimmune diseases (systemic lupus erythematosus), malignancy (in 10% of cases, most commonly lung and prostate cancer), drugs, and infections....

scholarly journals Alveolar epithelial surface area-volume relationship in isolated rat lungs

1999 ◽  
Vol 86 (6) ◽  
pp. 2026-2033 ◽  
Author(s):  
Daniel J. Tschumperlin ◽  
Susan S. Margulies
Keyword(s):  
Basement Membrane ◽  
Surface Area ◽  
Total Lung Capacity ◽  
Membrane Surface ◽  
Epithelial Surface ◽  
Alveolar Epithelial ◽  
Lung Capacity ◽  
Epithelial Basement Membrane ◽  
Rat Lungs ◽  
Epithelial Basement

In vitro studies of the alveolar epithelial response to deformation require knowledge of the in situ mechanical environment of these cells. Because of the presence of tissue folding and crumpling, previous measurements of the alveolar surface area available for gas exchange are not equivalent to the epithelial surface area. To identify epithelial deformations in uniformly inflated lungs representative of the in vivo condition, we studied isolated Sprague-Dawley rat lungs ( n = 31) fixed by perfusion with glutaraldehyde on deflation after cycling three times at high lung volume (10–25 cmH2O). The epithelial basement membrane in 45 electron micrographs (×12,000)/rat was traced, digitally scanned, and analyzed. Epithelial basement membrane surface area (EBMSA) was computed from a morphometric relationship. EBMSA was found to increase 5, 16, 12, and 40% relative to EBMSA at 24% total lung capacity at lung volumes of 42, 60, 82, and 100% total lung capacity, respectively. The increases in EBMSA suggest that epithelial cells undergo significant deformations with large inflations and that alveolar basement membrane deformation may contribute to lung recoil at high lung pressures.

Extent of glomerular injury in active and resolving lupus nephritis: a theoretical analysis

1991 ◽  
Vol 260 (5) ◽  
pp. F717-F727 ◽  
Author(s):  
B. D. Myers ◽  
A. Chagnac ◽  
H. Golbetz ◽  
L. Newton ◽  
S. Strober ◽  
...  
Keyword(s):  
Lupus Nephritis ◽  
Marked Reduction ◽  
Filtration Rate ◽  
Pore Density ◽  
Glomerular Injury ◽  
Biopsy Tissue ◽  
Structural Recovery ◽  
Proliferative Lupus Nephritis ◽  
Conventional Tests ◽  
Filtration Surface

Patients with diffuse, proliferative lupus nephritis (DPLN) were subjected to differential solute clearances (n = 22) and serial renal biopsy (n = 11) before and again after 6-12 mo of immunosuppressive therapy. Glomerular sieving of dextrans of graded size was analyzed with a heteroporous membrane model. This revealed active DPLN to be associated with 1) a reduction of overall pore density accompanied by a 53% depression of glomerular filtration rate (GFR), and 2) appearance of a subset of large, nondiscriminatory pores, which accounted for the observed nephrotic level of proteinuria. Morphometric analysis of biopsy tissue provided evidence of reduced filtration surface area due to global or segmental occlusion of capillary loops in glomerular tufts. Activity of DPLN resolved posttreatment. A computed increase in pore density was associated with a 24% increment in GFR; a marked reduction in the fraction of shuntlike pores was accompanied by a parallel reduction of proteinuria into a subnephrotic range. Repeat biopsy revealed diminished glomerular cellularity, fewer immune deposits, and an ensuing increase in the fraction of tuft area occupied by patent loops. Epithelial filtration slit frequency also increased. Neither functional nor structural recovery was complete, however. Residual pore density approximated only 23-35% of that in healthy controls, and corresponding shuntlike pores were threefold more prominent. We conclude that severe DPLN is only partially reversible by current modalities of treatment and that the ensuing residual injury is far more severe than suggested by conventional tests of renal function.

scholarly journals Mechanisms of T cell-induced glomerular injury in anti-glomeruler basement membrane (GBM) glomerulonephritis in rats

1997 ◽  
Vol 109 (1) ◽  
pp. 134-142 ◽  
Author(s):  
X. R. HUANG ◽  
P. G. TIPPING ◽  
J. APOSTOLOPOULOS ◽  
C. OETTINGER ◽  
M. D'SOUZA ◽  
...  
Keyword(s):  
T Cell ◽  
Basement Membrane ◽  
Glomerular Injury

Evolution of Membranous Nephropathy into Anti-Glomerular-Basement-Membrane Glomerulonephritis

1974 ◽  
Vol 290 (24) ◽  
pp. 1340-1344 ◽  
Author(s):  
John Klassen ◽  
Charles Elwood ◽  
Allan L. Grossberg ◽  
Felix Milgrom ◽  
Mario Montes ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Membranous Nephropathy
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