bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of Angiotensin II and Mechanical Stretch on Vascular Endothelial Growth Factor Production by Human Mesangial Cells
Authors: GRUDEN GABRIELLA , THOMAS STEPHEN , BURT DAVINA , ZHOU WUDIN , CHUSNEY GARY , GNUDI LUIGI , VIBERTI GIANCARLO 
Published: April 2021

Abstract.
The antiproteinuric effect of angiotensin-converting enzyme inhibitors underscores the importance of a hemodynamic injury and the renin-angiotensin system in the proteinuria of various glomerular diseases. Vascular endothelial growth factor (VEGF), a potent promoter of vascular permeability, is induced in mesangial cells by both mechanical stretch and TGF-β1. This study investigates the effect of TGF-β blockade, angiotensin II (AngII), and the interaction between AngII and stretch on human mesangial cell VEGF production. Exposure to AngII (1 μM) induced a significant increase in VEGF mRNA and protein levels (1.5 ± 0.1 and 1.7 ± 0.3, respectively, fold increase over control, P < 0.05). The AngII receptor (AT1) antagonist Losartan (10 μM) prevented AngII-induced, but not stretch-induced, VEGF protein secretion (AngII 1.7 ± 0.3, AngII + Losartan 1.0 ± 0.1, P < 0.05; stretch 2.4 ± 0.4, stretch + Losartan 2.6 ± 0.5). Stretch-induced VEGF production was also unaffected by the addition of an anti-TGF-β neutralizing antibody (stretch 2.85 ± 0.82 versus stretch + anti-TGF-β 2.84 ± 0.01, fold increase over control). Simultaneous exposure to both AngII and stretch for 12 h had an additive effect on VEGF production (AngII 1.6 ± 0.1, stretch 2.6 ± 0.27, AngII + stretch 3.1 ± 0.35). Conversely, preexposure to stretch magnified AngII-induced VEGF protein secretion (unstretched + AngII 1.3 ± 0.0, stretched + AngII 1.9 ± 0.1, P < 0.01) with a parallel 1.5-fold increase in AT1 receptor levels. AngII and stretch can both independently induce VEGF production; in addition, mechanical stretch upregulates the AT1 receptor, enhancing the cellular response to AngII.
Antiproteinuric Therapy while Preventing the Abnormal Protein Traffic in Proximal Tubule Abrogates Protein- and Complement-Dependent Interstitial Inflammation in Experimental Renal Disease
Authors: ABBATE MAURO , ZOJA CARLA , ROTTOLI DANIELA , CORNA DANIELA , PERICO NORBERTO , BERTANI TULLIO , REMUZZI GIUSEPPE 
Published: April 2021

Abstract.
In proteinuric glomerulopathies, the excess traffic of proteins into the renal tubule is a candidate trigger of interstitial inflammatory and immune events leading to progressive injury, and a key target for the renoprotective action of antiproteinuric drugs. Among proteins trafficked to the proximal tubule, the third component of complement (C3) can be activated locally and contribute to inflammation at sites of protein reabsorption. Experiments were performed in rats with renal mass reduction (RMR, 5/6 nephrectomy) with the following aims: (1) to study Ig (IgG) and complement deposition in proximal tubules, and interstitial macrophage infiltration and MHC class II expression at intervals after surgery by double immunofluorescence analysis; (2) to assess whether lisinopril (angiotensin-converting enzyme inhibitor [ACEi], 25 mg/L in the drinking water, from either day 1 or day 7) limited IgG and C3 accumulation and interstitial inflammation at day 30. In 7-d remnant kidneys, intracellular staining for both IgG and C3 was detectable in proximal tubules in focal areas; C3 was restricted to IgG-positive tubular cells, and there were no interstitial ED-1 macrophage and MHC II-positive cellular infiltrates. In 14-d and 30-d remnant kidneys, proximal tubular IgG and C3 staining was associated with the appearance of interstitial infiltrates that preferentially localized to areas of tubules positive for both proteins. RMR rats given ACEi had no or limited increases in levels of urinary protein excretion, tubular IgG, and C3 reactivity, and interstitial cellular infiltrates in kidneys at 30 d, even when ACEi was started from day 7 after surgery. These findings document that (1) in RMR, IgG and C3 accumulation in proximal tubular cells is followed by leukocyte infiltration and MHC II overexpression in the adjacent interstitium; (2) ACEi while preventing proteinuria limits both tubular accumulation of IgG and C3 and interstitial inflammation. The data suggest that ACE inhibition can be renoprotective by limiting the early abnormal protein traffic in proximal tubule and consequent deleterious effects of excess protein reabsorption, including the accumulation and local activation of complement as well as the induction of chemokines and endothelin genes known to promote interstitial inflammation and fibrosis.
Mycophenolate Mofetil Therapy in Lupus Nephritis
Authors: DOOLEY MARY ANNE , COSIO FERNANDO G. , NACHMAN PATRICK H. , FALKENHAIN MICHAEL E. , HOGAN SUSAN L. , FALK RONALD J. , HEBERT LEE A. 
Published: April 2021

Abstract.
Controlled clinical trials in renal transplantation have demonstrated that mycophenolate mofetil is well tolerated and has lower renal transplant rejection rates than azathioprine regimens. This study reports on the clinical experiences at two institutions with mycophenolate mofetil (MMF) for severe lupus nephritis. Twelve patients with relapsing or resistant nephritis previously treated with cyclophosphamide therapy and one patient who refused cyclophosphamide as initial therapy for diffuse proliferative nephritis but accepted MMF were included. During combined MMF/prednisone therapy, serum creatinine values remained normal or declined from elevated values: mean change in serum creatinine was -0.26 ± 0.46 μM/L, P = 0.039. Proteinuria significantly decreased: mean change in urine protein-to-creatinine ratios was -2.53 ± 3.76, P = 0.039. Decreased serum complement component C3 and elevated anti-double-stranded DNA antibody levels at baseline improved in some, but not all, patients. The mean initial dose of MMF was 0.92 g/d (range, 0.5 to 2 g/d). The mean duration of therapy was 12.9 mo (range, 3 to 24 mo). Adverse events included herpes simplex stomatitis associated with severe leukopenia (n = 1), asymptomatic leukopenia (n = 2), nausea/diarrhea (n = 2), thinning of scalp hair (n = 1), pancreatitis (n = 1), and pneumonia without leukopenia (n = 1). Recurrence of the pancreatitis led to discontinuation of MMF in this patient; all other adverse events resolved with dose reduction. It is concluded that MMF is well tolerated and has possible efficacy in controlling major renal manifestations of systemic lupus erythematosus. Controlled clinical trials are needed to define the role of MMF in the management of lupus nephritis.
Corticosteroid-Dependent Sodium Transport in a Novel Immortalized Mouse Collecting Duct Principal Cell Line
Authors: BENS MARCELLE , VALLET VÉRONIQUE , CLUZEAUD FRANC[COMBINING CEDILLA]OISE , PASCUAL-LETALLEC LAURENT , KAHN AXEL , RAFESTIN-OBLIN MARIE E. , ROSSIER BERNARD C. , VANDEWALLE ALAIN 
Published: April 2021

Abstract.
The final control of sodium balance takes place in the cortical collecting duct (CCD) of the nephron, where corticosteroid hormones regulate sodium reabsorption by acting through mineralocorticoid (MR) and/or glucocorticoid (GR) receptors. A clone of principal CCD cells (mpkCCDc14) has been established that is derived from a transgenic mouse (SV40 large T antigen under the control of the SV40 enhancer/L-type pyruvate kinase promoter). Cells grown on filters form polarized monolayers with high electrical transepithelial resistance (R
T approximately 4700 Ω × cm2) and potential difference (P
D approximately -50 mV) and have an amiloride-sensitive electrogenic sodium transport, as assessed by the short-circuit current method (I
sc approximately 11 μA/cm2). Reverse transcription-PCR experiments using rat MR primers, [3H]aldosterone, and [3H]dexamethasone binding and competition studies indicated that the mpkCCDc14 cells exhibit specific MR and GR. Aldosterone increased Isc in a dose- (10-10 to 10-6 M) and time-dependent (2 to 72 h) manner, whereas corticosterone only transiently increased Isc (2 to 6 h). Consistent with the expression of 11β-hydroxysteroid dehydrogenase type 2, which metabolizes glucocorticoids to inactive 11-dehydroderivates, carbenoxolone potentiated the corticosterone-stimulated I
sc. Aldosterone (5 × 10-7 M)-induced I
sc (fourfold) was associated with a three- to fivefold increase in α-ENaC mRNA (but not in those for β- or γ-ENaC) and three- to 10-fold increases in α-ENaC protein synthesis. In conclusion, this new immortalized mammalian CCD clonal cell line has retained a high level of epithelial differentiation and sodium transport stimulated by aldosterone and therefore represents a useful mammalian cell system for identifying the genes controlled by aldosterone.
Endothelial Dysfunction in Acute Renal Failure
Authors: RUSCHITZKA FRANK , SHAW SIDNEY , GYGI DANIEL , NOLL GEORG , BARTON MATTHIAS , LÜSCHER THOMAS F. 
Published: April 2021

Abstract.
The kidney is an important target and source of the potent vasoconstrictor and mitogen endothelin-1 (ET-1). However, its exact role in acute renal failure (ARF) remains to be determined. ARF was induced in male Wistar-Kyoto rats (n = 7) in a 2-kidney, 2-clip model of 30-min clamping. Twentyfour hours after clamp release, contractions to angiotensin I (AngI) and II, ET-1, and big ET-1 were studied in isolated aortic and renal artery rings. Endothelium-dependent and -independent relaxations were assessed by acetylcholine and sodium nitroprusside. ET-1 clearance, tissue uptake, plasma levels, and vascular and kidney content were investigated. In addition, ETA and EtB receptor mRNA expression was determined. Sham-operated animals served as controls (n = 7). In ARF, ET-1 plasma levels and tissue content of the renal artery, the aorta, and the kidney markedly increased (P < 0.01). Plasma half-life of radiolabeled 125I-ET-1 was markedly prolonged, whereas 125I-ET-1 tissue uptake decreased in the kidney in ARF. Contractions to AngI and AngII were blunted (P < 0.05) and those to KC1 were unchanged, whereas vascular responses to big ET-1 and ET-1 were enhanced in the renal artery and also in the aorta in ARF (P < 0.05 to 0.001). Correspondingly, ETA and EtB receptor mRNA expression significantly increased in both vascular beds. In addition, endothelium-dependent relaxation to acetylcholine was diminished and inversely correlated with vascular ET-1 protein levels in the renal artery (r = -0.827, P < 0.001) and the aorta (r = -0.812, P < 0.001). In conclusion, the present study demonstrates that increase of circulating and tissue ET-1 protein levels and ETA and EtB receptor gene expression occurs, which induces endothelial dysfunction and enhanced vasoconstriction in different vascular beds in ARF.
Differential Effects of 1,25-Dihydroxy-Vitamin D3 and 19-Nor-1,25-Dihydroxy-Vitamin D2 on Calcium and Phosphorus Resorption in Bone
Authors: FINCH JANE L. , BROWN ALEX J. , SLATOPOLSKY EDUARDO 
Published: April 2021

Abstract.
1,25-Dihydroxy-vitamin D3 [1,25-(OH)2D3] suppresses the secretion and synthesis of parathyroid hormone (PTH) and has been used in the treatment of secondary hyperparathyroidism. However, 1,25-(OH)2D3 can induce hypercalcemia, which often precludes its use. Therefore, an analog of 1,25-(OH)2D3 that would retain its therapeutic effects but produce minor effects on calcium and phosphorus metabolism could be an ideal tool for the treatment of secondary hyperparathyroidism. It has been shown that 19-nor-1,25-dihydroxy-vitamin D2 [19-nor-1,25-(OH)2D2], an analog of 1,25-(OH)2D3, can suppress PTH levels in uremic rats at doses that do not affect plasma ionized calcium levels. The experiments presented here, using parathyroidectomized rats fed diets deficient in either calcium (0.02%) or phosphorus (0.02%), were performed to compare the effects of 1,25-(OH)2D3 and 19-nor-1,25-(OH)2D2 on calcium and phosphorus resorption in bone. Parathyroidectomized rats received daily intraperitoneal injections of vehicle, 1,25-(OH)2D3 (100 ng), or 19-nor-1,25-(OH)2D2 (100 or 1000 ng) for 9 d. Plasma calcium and phosphorus levels were monitored during the study, and ionized calcium levels were determined at the end of the study. By 9 d, 1,25-(OH)2D3 (100 ng/d) increased total calcium levels to 12.4 ± 0.26 mg/dl, compared with 6.32 ± 0.25 mg/dl (P < 0.001) in control animals. The same dose of 19-nor-1,25-(OH)2D2 (100 ng/d) was much less potent (9.45 ± 0.28 mg/dl, P < 0.001). Similar results were seen with ionized calcium levels [19-nor-1,25-(OH)2D2, 3.61 ± 0.12 mg/dl; 1,25-(OH)2D3, 5.03 ± 0.16 mg/dl; P < 0.001]. Ionized calcium levels were also lower in rats receiving the higher dose (1000 ng) of 19-nor-1,25-(OH)2D2 (4.59 ± 0.09 mg/dl, P < 0.05). Similar results were seen in rats fed the phosphorus-deficient diet. 1,25-(OH)2D3 (100 ng) increased plasma phosphorus levels from 4.30 ± 0.39 mg/dl in vehicle-treated rats to 7.43 ± 0.26 mg/dl (P < 0.001). The same dose of 19-nor-1,25-(OH)2D2 had no effect (5.19 ± 0.32 mg/dl), whereas the high dose (1000 ng) increased plasma phosphorus levels (7.31 ± 0.24 mg/dl) in a manner similar to that of 1,25-(OH)2D3 (100 ng). Therefore, 19-nor-1,25-(OH)2D2 is approximately 10 times less effective in mobilizing calcium and phosphorus from the skeleton, compared with 1,25-(OH)2D3. With its ability to suppress PTH at noncalcemic doses, 19-nor-1,25-(OH)2D2 is a potential therapeutic tool for the treatment of secondary hyperparathyroidism in chronic renal failure.
Molecular Cloning of NHE3 from LLC-PK1 Cells and Localization in Pig Kidney
Authors: SHUGRUE CHRISTINE A. , OBERMÜLLER NICHOLAS , BACHMANN SEBASTIAN , SLAYMAN CAROLYN W. , REILLY ROBERT F. 
Published: April 2021

Abstract.
LLC-PK1 cells, an established line from pig kidney, express basolateral and apical Na+/H+ exchangers that can be distinguished by their differing sensitivities to the amiloride analog N-ethyl-N-isopropylamiloride (EIPA). It has been shown previously that the basolateral exchanger is encoded by NHE1. In the present study, a combination of reverse transcription-PCR, 5′ RACE, and genomic library screening was used to clone the coding region of the porcine NHE3 gene. There was significant homology between the LLC-PK1 sequence and the previously reported rabbit and rat NHE3 genes, with nucleotide and deduced amino acid identities of 87 and 85% in rabbit, and 85 and 87% in rat, respectively. To study expression patterns, Northern analysis was carried out using an NHE3 cDNA to probe poly(A)+ RNA isolated from LLC-PK1 cells, and from pig kidney cortex. In all three cases, a major transcript of 6.1 kb was detected along with two minor transcripts of 4.7 and 3.8 kb. In situ hybridization with two different NHE3 probes gave intense labeling of the distal convoluted tubule in pig kidney but (unexpectedly) no detectable labeling of the proximal tubule. These studies suggest that there are marked species differences in NHE3 expression in the distal nephron.
Decreased Abundance of Collecting Duct Aquaporins in Post-Ischemic Renal Failure in Rats
Authors: FERNÁNDEZ-LLAMA PATRICIA , ANDREWS PETER , TURNER RACHEL , SAGGI SUBODH , DIMARI JOHN , KWON TAE-HWAN , NIELSEN SØREN , SAFIRSTEIN ROBERT , KNEPPER MARK A. 
Published: April 2021

Abstract.
Increased urine flow is often a feature of mild to moderate acute renal failure. This study examines the possible role of dysregulation of collecting duct aquaporins as a factor in this increase. In rats, the left renal pedicle was clamped for 45 min followed by contralateral nephrectomy. Control rats were identical except that the renal pedicle was not clamped. Rats were sacrificed and the kidneys were homogenized at various time points after release of the clamp for semiquantitative immunoblotting of collecting duct aquaporins, as well as the thick ascending limb Na-K-2Cl cotransporter and the proximal tubule water channel, aquaporin-1. Urinary flow rate was significantly increased 18 h after the ischemic insult and remained increased through 72 h. Whole kidney aquaporin-2 protein abundance was 45% of controls at 18 h, 55% of controls at 36 h, and returned to normal 72 h after ischemia. Whole kidney aquaporin-3 protein abundance was 37% of controls at 18 h, 13% of controls at 36 h, and 45% of controls at 72 h. The decline in aquaporin-2 and -3 was confirmed by immunocytochemistry. Abundance of the thick ascending limb Na-K-2Cl cotransporter protein was not significantly decreased. Aquaporin-1 protein abundance was not significantly decreased at 18 h after the ischemic insult, but was significantly reduced after 36 h. Thus, the post-ischemic state is associated with decreased levels of the collecting duct aquaporins, coinciding with an increase in water excretion. It is concluded that decreased aquaporin protein abundance in collecting duct cells is a contributing factor in the increased urine flow seen in moderate post-ischemic acute renal failure.
The Long-Term Outcome of Patients with IgA Nephropathy Treated with Fish Oil in a Controlled Trial
Authors: DONADIO JAMES V. , GRANDE JOSEPH P. , BERGSTRALH ERIK J. , DART RICHARD A. , LARSON TIMOTHY S. , SPENCER DOROTHY C. 
Published: April 2021

Abstract.
It was reported previously that dietary fish oil supplementation retarded the progression of renal disease in patients with IgA nephropathy in a multicenter, placebo-controlled, randomized, 2-yr clinical trial. The aim of this study was to determine the long-term influence of fish oil treatment on renal progression in observations on the study cohort of 106 patients extending beyond the 2-yr trial. Renal function was assessed by serial serum creatinine and 24-h urine protein measurements. Vital, end-stage renal disease (ESRD), and BP status and treatment beyond completion of the 2-yr trial were determined. As in the trial, the primary end point was an increase of 50% or more in the serum creatinine, and the secondary end point was ESRD. After a mean follow-up of 6.4 yr, 46 patients—17 in the fish oil group versus 29 in the placebo group—reached the primary end point (P = 0.002), and 27 patients—eight in the fish oil group versus 19 in the placebo group—developed ESRD (P = 0.009). At the end of the 2-yr trial, 75 patients (45 fish oil, 30 placebo) remained at risk for the primary end point. This is also when the double-blind part of the trial ended, allowing physicians to stop supplements, switch original placebo-assigned patients to fish oil, and continue fish oil in original fish oil-assigned patients. A significantly greater number of nonsupplemented placebo patients developed the primary end point (P = 0.02) and ESRD (P = 0.003) compared with long-term supplemented fish oil patients. Conversely, more fish oil-supplemented patients had stable renal function than nonsupplemented patients (P = 0.02). By intention, BP control, primarily treated with angiotensin-converting enzyme inhibition, was equal in the fish oil and placebo groups. Proteinuria was modestly reduced in both groups. It is concluded that early and prolonged treatment with fish oil slows renal progression for high-risk patients with IgA nephropathy.
Inherited Disorders of Renal Magnesium Handling
Authors: COLE DAVID E. C. , QUAMME GARY A. 
Published: April 2021

Abstract.
The genetic basis and cellular defects of a number of primary magnesium wasting diseases have been elucidated over the past decade. This review correlates the clinical pathophysiology with the primary defect and secondary changes in cellular electrolyte transport. The described disorders include (1) hypomagnesemia with secondary hypocalcemia, an earlyonset, autosomal-recessive disease segregating with chromosome 9q12-22.2; (2) autosomal-dominant hypomagnesemia caused by isolated renal magnesium wasting, mapped to chromosome 11q23; (3) hypomagnesemia with hypercalciuria and nephrocalcinosis, a recessive condition caused by a mutation of the claudin 16 gene (3q27) coding for a tight junctional protein that regulates paracellular Mg2+ transport in the loop of Henle; (4) autosomal-dominant hypoparathyroidism, a variably hypomagnesemic disorder caused by inactivating mutations of the extracellular Ca2+/Mg2+-sensing receptor, Casr gene, at 3q13.3-21 (a significant association between common polymorphisms of the Casr and extracellular Mg2+ concentration has been demonstrated in a healthy adult population); and (5) Gitelman syndrome, a recessive form of hypomagnesemia caused by mutations in the distal tubular NaCl cotransporter gene, SLC12A3, at 16q13. The basis for renal magnesium wasting in this disease is not known. These inherited conditions affect different nephron segments and different cell types and lead to variable but increasingly distinguishable phenotypic presentations. No doubt, there are in the general population other disorders that have not yet been identified or characterized. The continued use of molecular techniques to probe the constitutive and congenital disturbances of magnesium metabolism will increase the understanding of cellular magnesium transport and provide new insights into the way these diseases are diagnosed and managed.
AP-1 Proteins Mediate Hyperglycemia-Induced Activation of the Human TGF-β1 Promoter in Mesangial Cells
Authors: WEIGERT CORA , SAUER ULRICH , BRODBECK KATRIN , PFEIFFER ANDREAS , HA[Combining Diaeresis]RING HANS U. , SCHLEICHER ERWIN D. 
Published: April 2021

Abstract.
Hyperglycemia-induced overproduction of the prosclerotic cytokine transforming growth factor-β1 (TGF-β1) has been implicated in the pathogenesis of diabetic nephropathy. Because high glucose and phorbol esters (PMA) increase TGF-β1 mRNA levels in mesangial cells, this study was designed to characterize these effects on the human TGF-β1 promoter activity. With the use of luciferase reporter gene constructs containing TGF-β1 5′-flanking sequence (from -453 to +11 bp) transfected into mesangial cells, it was found that 30 mM glucose induced a nearly twofold increase in TGF-β1 promoter activity after 24 h of incubation in human and porcine mesangial cells. Stimulation by PMA was more effective (2.3-fold). Mutagenesis in either one of the two or both activating protein-1 (AP-1) binding sites abolished the high glucose and the PMA effect. Furthermore, addition of the AP-1 inhibitor curcumin obliterated the glucose response. Corresponding experiments revealed that the transcription factor stimulating protein 1 was not involved in mediating the glucose effect. The high glucose-induced TGF-β1 promoter activation was also prevented by inhibitors of protein kinase C and p38 mitogen-activated proteinkinase. Electrophoretic mobility shift assays with oligonucleotides containing one of the two AP-1 binding sites showed that glucose treatment markedly enhanced the binding activity of nuclear proteins of mesangial cells, particularly to box B. Supershift assays demonstrated that JunD and c-Fos were present in the protein-DNA complexes under control and hyperglycemic conditions. The functional and structural results show that glucose regulates human TGF-β1 gene expression through two adjacent AP-1 binding sites and gives rise to the involvement of protein kinase C and p38 mitogen-activated proteinkinase in hyperglycemia-induced TGF-β1 gene expression.