bluuebunny/crossref_metadata_2025_split huggingface dataset:
Angiotensin II Binding to Renomedullary Interstitial Cells Is Regulated by Osmolality
Authors: MARIC CHRISTINE , CASLEY DAVID , HARRIS PETER J. , ALCORN DAINE 
Published: April 2021

Abstract.
Angiotensin II (Ang II) AT1A receptors are localized to renomedullary interstitial cells (RMIC) in the inner stripe of the outer medulla but not in the inner medulla. Thus, there seems to be a correlation between decreases in AT1A receptor binding to RMIC and increases in interstitial osmolality, suggesting that osmolality is important in determining Ang II binding to RMIC. Cultured RMIC were incubated in media of differing osmolalities (330, 630, 930, and 1230 mOsm/kgH2O). 125I-[Sar1, Ile8] Ang II binding to AT1A receptors on RMIC grown in hyperosmolal media (930 mOsm/kgH2O) was reduced compared with isoosmolal (330 mOsm/kgH2O) media and was progressively reduced with further increases of osmolality. Similar studies were performed using bradykinin (BK) as a control peptide. Binding of the BK receptor ligand 125I-[HPP-Hoe 140] to B2 receptors was not affected by varying osmolality of the media. Reverse transcriptase-PCR demonstrated the presence of the mRNA expression for both AT1A and B2 receptors at each osmolality. The conclusion is that osmolality modulates Ang II binding to RMIC; in these cells, this phenomenon is restricted to Ang II as BK binding is not affected. Osmolality-induced changes in Ang II binding may modulate the actions of this peptide on RMIC and provide an important mechanism by which these cells modulate renal medullary function.
Kinetics of Connective Tissue Growth Factor Expression during Experimental Proliferative Glomerulonephritis
Authors: ITO YASUHIKO , GOLDSCHMEDING ROEL , BENDE RICHARD J. , CLAESSEN NIKE , CHAND M. ANWAR , KLEIJ LIVIO , RABELINK TON J. , WEENING JAN J. , ATEN JAN 
Published: April 2021

Abstract.
Connective tissue growth factor (CTGF) is a member of the CCN family of immediate early genes, which are involved in cell proliferation, migration, and matrix production. Recently, CTGF was observed to be strongly upregulated in human proliferative and fibrogenic renal disease. By in situ hybridization and reverse transcriptase-PCR, the expression of CTGF was investigated in experimental proliferative glomerulonephritis induced by injection of anti—Thy-1.1 antibody in the rat. CTGF expression in cultured rat mesangial cells and glomerular visceral epithelial cells (GVEC) was studied in response to transforming growth factor β (TGF-β), an essential pathogenetic factor in this model. In normal rat kidneys, only some GVEC expressed CTGF mRNA. In anti—Thy-1.1 nephritis, CTGF mRNA expression was strongly increased in extracapillary and mesangial proliferative lesions and in areas of periglomerular fibrosis. Early glomerular CTGF overexpression in GVEC coincided with a striking upregulation of TGF-β2 and to a lesser extent of TGF-β3. Glomerular CTGF mRNA expression was maximal at day 7, in association with increased TGF-β1 mRNA and protein expression. CTGF mRNA overexpression by parietal epithelial cells preceded the periglomerular appearance of α-smooth muscle actin—positive fibroblasts. In cultured mesangial cells, TGF-β1, -β2, and -β3 transiently increased the CTGF/glyceraldehyde phosphate dehydrogenase mRNA ratio up to threefold versus control at 4 h. In GVEC, upregulation of CTGF mRNA by these TGF-β isoforms was more sustained, being 8- to 16-fold versus control at 24 h. The kinetics of CTGF expression strongly suggest a role in glomerular repair, possibly downstream of TGF-β, in this model of transient renal injury.
Apoptosis and Caspase-3 in Experimental Anti-Glomerular Basement Membrane Nephritis
Authors: YANG BIN , JOHNSON TIMOTHY S. , THOMAS GRAHAM L. , WATSON PHILIP F. , WAGNER BART , NAHAS A. MEGUID EL 
Published: April 2021

Abstract.
The caspase family is central to the proteolytic events of apoptosis. In particular, caspase-3 plays a key role in the execution of apoptosis. However, the importance of caspase-3 in renal cell apoptosis during kidney scarring has not been established. Here, nephrotoxic nephritis (NTN) was induced in Wistar Kyoto rats by a single intravenous injection of rabbit anti-rat glomerular basement membrane serum, with analysis at days 7, 15, 30, and 45 after injection. Cell apoptosis (in situ end labeling of DNA, light and electron microscopy), proliferation (proliferating cell nuclear antigen-positive cells), and inflammation (ED1-positive cells) all increased in NTN kidneys, peaking early (day 7) in the glomeruli and later (days 30 to 45) in the tubules and interstititum. The expression of caspase-3 mRNA (Northern blotting) was increased in NTN kidneys on days 7, 30, and 45 (173.3%, 228%, and 241.7%, respectively; P < 0.05). Western blotting showed that a 24-kD protein band (caspase-3 active subunit) increased with time in NTN kidneys (P < 0.01) and reached a maximum on day 45 (6.08-fold increase). A 32 kD band (caspase-3 precursor) was also increased on day 45 (3.92-fold; P < 0.01). Elevated caspase-3 activity (two- to threefold) was observed in NTN kidneys at all time points (P < 0.01). Upregulated expression of caspase-3 at all levels positively correlated with apoptosis, whereas both correlated closely with inflammation, proliferation, and subsequent fibrosis in glomeruli, tubules, and interstitium (P < 0.05). Inhibition of caspase-3 during the course of experimental nephritis may offer a new therapeutic approach for the prevention of renal apoptosis and the associated renal tubular atrophy and fibrosis.
Tracer Studies in the Rat Demonstrate Misdirected Filtration and Peritubular Filtrate Spreading in Nephrons with Segmental Glomerulosclerosis
Authors: KRIZ WILHELM , HARTMANN INGRID , HOSSER HILTRAUD , HA[Combining Diaeresis]HNEL BRUNHILDE , KRA[Combining Diaeresis]NZLIN BETTINA , PROVOOST ABARAHAM P. , GRETZ NORBERT 
Published: April 2021

Abstract.
In two genetic models of “classic” focal segmental glomerulosclerosis (FSGS), the Milan normotensive and the Fawn-hooded hypertensive rats, tracer studies were performed to test the hypothesis that misdirected glomerular filtration and peritubular filtrate spreading are relevant mechanisms that contribute to nephron degeneration in this disease. Two exogenous tracers, lissamine green and horse spleen ferritin, were administered by intravenous injection and subsequently traced histologically in serial kidney sections. In contrast to control rats, both tracers in kidneys of Milan normotensive and Fawn-hooded hypertensive rats with established FSGS were found to accumulate extracellularly at the following sites: (1) within tuft adhesions to Bowman's capsule and associated paraglomerular spaces, (2) at the glomerulotubular junction contained within extensions of the paraglomerular spaces onto the tubule, and (3) within subepithelial peritubular spaces eventually encircling the entire proximal convolution of an affected nephron. This distribution strongly suggests the existence of misdirected filtration into tuft adhesions to Bowman's capsule and subsequent spreading of the filtrate around the entire circumference of a glomerulus and, alongside the glomerulotubular junction, onto the outer aspect of the corresponding tubule. This leads to an interstitial response that consists of the formation of a barrier of sheet-like fibroblast processes around the affected nephron, which confines the filtrate spreading and, subsequently, the destructive process to the affected nephron. No evidence was found that either misdirected filtration and peritubular filtrate spreading themselves or the associated tubulo-interstitial process led to the transfer of the injury from an affected nephron to an unaffected nephron. It is concluded that in the context of FSGS development, misdirected filtration and peritubular filtrate spreading are important damaging mechanisms that underlie the extension of glomerular injury to the corresponding tubulointerstitium, thus leading finally to degeneration of both the glomerulus and the tubule of a severely injured nephron.
Role of CFTR in Autosomal Recessive Polycystic Kidney Disease
Authors: NAKANISHI KOICHI , SWEENEY WILLIAM E. , MACRAE DELL KATHERINE , COTTON CALVIN U. , AVNER ELLIS D. 
Published: April 2021

Abstract.
An extensive body of in vitro data implicates epithelial chloride secretion, mediated through cystic fibrosis transmembrane conductance regulator (CFTR) protein, in generating or maintaining fluid filled cysts in MDCK cells and in human autosomal dominant polycystic kidney disease (ADPKD). In contrast, few studies have addressed the pathophysiology of fluid secretion in cyst formation and enlargement in autosomal recessive polycystic kidney disease (ARPKD). Murine models of targeted disruptions or deletions of specific genes have created opportunities to examine the role of individual gene products in normal development and/or disease pathophysiology. The creation of a murine model of CF, which lacks functional CFTR protein, provides the opportunity to determine whether CFTR activity is required for renal cyst formation in vivo. Therefore, this study sought to determine whether renal cyst formation could be prevented by genetic complementation of the BPK murine model of ARPKD with the CFTR knockout mouse. The results of this study reveal that in animals that are homozygous for the cystic gene (bpk), the lack of functional CFTR protein on the apical surface of cystic epithelium does not provide protection against cyst growth and subsequent decline in renal function. Double mutant mice (bpk -/-; cftr -/-) developed massively enlarged kidneys and died, on average, 7 d earlier than cystic, non-CF mice (bpk -/-; cftr +/±). This suggests fundamental differences in the mechanisms of transtubular fluid secretion in animal models of ARPKD compared with ADPKD.
Klf6 Is a Zinc Finger Protein Expressed in a Cell-Specific Manner during Kidney Development
Authors: FISCHER EVELYNE A. , VERPONT MARIE-CHRISTINE , GARRETT-SINHA LEE ANN , RONCO PIERRE M. , ROSSERT JEROME A. 
Published: April 2021

Abstract.
Molecular mechanisms that are responsible for the development of the renal collecting duct system during embryogenesis are still poorly understood. A mouse cDNA encoding a zinc finger protein, called Klf6, which is a member of the Kru[Combining Diaeresis]ppel-like family of transcription factors, has been cloned. Northern blot analyses showed that Klf6 was already expressed in 11.5-d postconception mouse embryos and that its expression persisted after birth. They also disclosed that Klf6 had a restricted pattern of expression. In situ hybridization experiments using mouse embryos showed that during kidney development, Klf6 was expressed selectively in the Wolffian duct and in its derivatives. During mesonephros development, it was expressed in the Wolffian duct but not in the mesonephric mesenchyme. Thereafter, Klf6 was expressed in the ureteric bud and its branches and in the collecting ducts, whereas it was not expressed in tubular structures that derive from the metanephric mesenchyme. Glomeruli were not labeled during early stages of differentiation, and it is only at the capillary stage that a staining of the mesangial area was observed, which persisted after birth. This pattern of expression is strikingly similar to the one of GATA-3, which is another zinc finger protein. It suggests that Klf6 may play a role during kidney development and in particular during the development of the renal collecting duct system, possibly in association with GATA-3.
Pharmacokinetic Interactions Augment Toxicities of Sirolimus/Cyclosporine Combinations
Authors: PODDER HEMANGSHU , STEPKOWSKI STANISLAW M. , NAPOLI KIMBERLY L. , CLARK JAMES , VERANI REGINA R. , CHOU TING-CHAO , KAHAN BARRY D. 
Published: April 2021

Abstract.
This study correlated the dynamic effects of sirolimus (rapamycin; RAPA) and cyclosporine (CsA) alone versus in combination to produce renal dysfunction, myelosuppression, or hyperlipidemia, with their corresponding blood and tissue concentrations. After salt-depleted rats were treated with RAPA (0.4 to 6.4 mg/kg per d) and/or CsA (2.5 to 20.0 mg/kg per d) for 14 d, the GFR, lipid levels, bone marrow cellularity, and CsA/RAPA concentrations in whole blood versus liver or renal tissues were measured, and the median effect model was used to discern the type of drug interactions. Compared with vehicle controls (1.98 ± 0.34 ml/min), GFR values were reduced only by large doses of drug monotherapy, namely RAPA (3.2 mg/kg per d = 1.2 ± 0.02 ml/min or 6.4 mg/kg per d = 1.3 ± 0.2 ml/min; both P < 0.01) or CsA (10.0 mg/kg per d = 1.2 ± 0.1 ml/min or 20.0 mg/kg per d = 0.8 ± 0.4 ml/min; both P < 0.01). In contrast, hosts that were treated with smaller doses of CsA/RAPA combinations showed more pronounced effects in reduction of GFR values: 2.5/0.4 mg/kg per d, modestly (1.5 ± 0.5 ml/min; P < 0.01); 5.0/0.8 mg/kg per d, moderately (0.23 ± 0.01 ml/min; P < 0.001); and higher-dose groups, markedly. The exacerbation of renal dysfunction seemed to be due to a pharmacokinetic interaction of RAPA to greatly increase CsA concentrations in whole blood and, particularly, in kidney tissue. In contrast, the pharmacodynamic effects of CsA to potentiate two RAPA-mediated toxicities—myelosuppression and increased serum cholesterol/low-density lipoprotein cholesterol—occurred independently of pharmacokinetic interactions. RAPA aggravates CsA-induced renal dysfunction owing to a pharmacokinetic interaction, whereas CsA produces a pharmacodynamic effect that augments RAPA-induced myelosuppression and hyperlipidemia.
DNA Microarray Analysis of Complex Biologic Processes
Authors: KURELLA MANJULA , HSIAO LI-LI , YOSHIDA TAKUMI , RANDALL JEFFREY D. , CHOW GARY , SARANG SATINDER S. , JENSEN RODERICK V. , GULLANS STEVEN R. 
Published: April 2021

Abstract.
DNA microarrays, or gene chips, allow surveys of gene expression, (i.e., mRNA expression) in a highly parallel and comprehensive manner. The pattern of gene expression produced, known as the expression profile, depicts the subset of gene transcripts expressed in a cell or tissue. At its most fundamental level, the expression profile can address qualitatively which genes are expressed in disease states. However, with the aid of bioinformatics tools such as cluster analysis, self-organizing maps, and principle component analysis, more sophisticated questions can be answered. Microarrays can be used to characterize the functions of novel genes, identify genes in a biologic pathway, analyze genetic variation, and identify therapeutic drug targets. Moreover, the expression profile can be used as a tissue or disease “fingerprint.” This review details the fabrication of arrays, data management tools, and applications of microarrays to the field of renal research and the future of clinical practice.
Induction of Collecting Duct Morphogenesis In Vitro by Heparin-Binding Epidermal Growth Factor-Like Growth Factor
Authors: TAKEMURA TSUKASA , HINO SATOSHI , KUWAJIMA HIROAKI , YANAGIDA HIDEHIKO , OKADA MITSURU , NAGATA MICHIO , SASAKI SEI , BARASCH JONATHAN , HARRIS RAYMOND C. , YOSHIOKA KAZUO 
Published: April 2021

Abstract.
Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the epidermal growth factor family of growth factors, is synthesized as a membrane-an-chored precursor (proHB-EGF) that is capable of stimulating adjacent cells in a juxtacrine manner. ProHB-EGF is cleaved in a protein kinase C-dependent process, to yield the soluble form. It was observed that HB-EGF acts as a morphogen for the collecting duct system in developing kidneys. HB-EGF protein was expressed in the ureteric bud of embryonic kidneys. Cultured mouse ureteric bud cells (UBC) produced HB-EGF via protein kinase C activation. After stimulation with phorbol ester (12-O-tetradecanoylphorbol-13-acetate) or recombinant soluble HB-EGF, UBC cultured in three-dimensional collagen gels formed short tubules with varied abundant branches. When proHB-EGF-transfected UBC were stimulated with 12-O-tetradecanoylphorbol-13-acetate and cultured in collagen gels, they exhibited linear growth, forming long tubular structures with few branches at the time of appearance of proHB-EGF on the cell surface. The structures exhibited a strong resemblance to the early branching ureteric bud of embryonic kidneys. When UBC were cultured in the presence of transforming growth factor-β and soluble HB-EGF, they formed long tubules and few branches, similar to the structures observed in proHB-EGF-transfected UBC. These cells exhibited apical-basolateral polarization and expression of the water channel aquaporin-2. These findings indicate that soluble HB-EGF and proHB-EGF induce branching tubulogenesis in UBC in different ways. Juxtacrine activation by proHB-EGF or the synergic action of soluble HB-EGF with transforming growth factor-β is important for well balanced morphogenesis of the collecting duct system.
De Novo Demonstration and Co-localization of Free-Radical Production and Apoptosis Formation in Rat Kidney Subjected to Ischemia/Reperfusion
Authors: CHIEN CHIANG-TING , LEE PO-HUANG , CHEN CHAU-FONG , MA MING-CHIEH , LAI MING-KUEN , HSU SU-MING 
Published: April 2021

Abstract.
Ischemia-induced oxidative damage to the reperfused kidney was examined. A modified chemiluminescence method, an in situ nitro blue tetrazolium perfusion technique, and a DNA fragmentation/apoptosis-related protein assay were adapted for demonstration de novo and co-localization of reactive oxygen species (ROS) production and apoptosis formation in rat kidneys subjected to ischemia/reperfusion injury. The results showed that prolonged ischemia potentiated proapoptotic mechanisms, including increases in the Bax/Bcl-2 ratio, CPP32 expression, and poly-(ADP-ribose)-polymerase fragments, and subsequently resulted in severe apoptosis, including increases in DNA fragmentation and apoptotic cell number in renal proximal tubules (PT) and distal tubules (DT) in a time-dependent manner. The increased level of ROS detected on the renal surface was correlated with that in blood and was intensified by a prolonged interval of ischemia. The main source of ROS synthesis was the PT epithelial cells. The ROS and apoptotic nuclei detected in the PT cells can be ameliorated by superoxide dismutase (SOD) treatment before reperfusion. However, the apoptotic nuclei remained in DT in the SOD-treated rats, indicating that formation of apoptosis in DT was not influenced by the small amounts of ROS produced. In PT and DT cell cultures, significant increases in apoptotic cells and ROS were evident in PT cells after hypoxia/reoxygenation insult. Furthermore, the oxidative damage in PT, but not in DT, can be alleviated by ROS scavengers SOD and hexa(sulfobutyl)fullerene, confirming that PT are vulnerable to ROS. These results lead us to conclude that ROS produced in significant amounts in PT epithelium under ischemia/reperfusion or hypoxia/reoxygenation conditions may be responsible for the apoptotic death of these cells.
Loop Diuretic Infusion Increases Thiazide-Sensitive Na+/Cl--Cotransporter Abundance
Authors: ABDALLAH JOSEPH G. , SCHRIER ROBERT W. , EDELSTEIN CHARLES , JENNINGS SUSAN D. , WYSE BRUCE , ELLISON DAVID H. 
Published: April 2021

Abstract.
Chronic infusion of loop diuretics into animals induces structural and functional changes in the distal nephron. These changes include increases in the activity of the thiazide-sensitive Na+/Cl--cotransporter (NCC). The NCC was recently demonstrated to be an aldosterone-induced protein. These experiments were designed to test the hypotheses that chronic loop diuretic infusion, with replacement of NaCl losses, increases NCC protein abundance and that this effect results, in part, from stimulation by aldosterone. Sprague-Dawley rats received vehicle (group 1), furosemide (22 mg/100 g body wt per d) (group 2), or furosemide plus spironolactone (22 and 20 mg/100 g body wt per d, respectively) (group 3). Urine output was higher for groups 2 and 3 than for group 1 (151 ± 32, 149 ± 24, and 12 ± 4 ml, respectively; P < 0.0001). Immunoblot analysis of NCC protein demonstrated that loop diuretics increased NCC protein abundance by nearly 100% (from 2562 ± 30 to 5248 ± 151 arbitrary units, P < 0.01). Spironolactone decreased NCC protein abundance by 66% (to 3532 ± 113 units), compared with the furosemide-treated group (P < 0.005). Northern blot analysis of NCC mRNA demonstrated no significant effect of furosemide (NCC/glyceraldehyde-3-phosphate dehydrogenase ratios: group 1, 0.6 ± 0.12; group 2, 0.5 ± 0.05; P > 0.05, NS) These results indicate that increased NCC activity during chronic loop diuretic infusion is associated with increases in NCC protein abundance. A portion of the furosemide effect can be prevented by blockade of mineralocorticoid receptors.
Use of Positron Emission Tomography to Study AT1 Receptor Regulation In Vivo
Authors: SZABO ZSOLT , SPETH ROBERT C. , BROWN P. RANDY , KERENYI LEVENTE , KAO PAN FU , MATHEWS WILLIAM B. , RAVERT HAYDEN T. , HILTON JOHN , RAUSEO PAIGE , DANNALS ROBERT F. , ZHENG WEI , LEE SUNGHOU , SANDBERG KATHRYN 
Published: April 2021

Abstract.
Increased sodium intake and enhanced sodium sensitivity are implicated in the pathogenesis of hypertension and in the control of a major regulator of BP, the type 1 angiotensin receptor (AT1 receptor). An in vivo technique to study changes of renal AT1 receptors by dietary sodium was developed that uses positron emission tomography (PET). PET revealed that renal cortical AT1 receptor binding was increased in sodium-loaded compared with sodium-deprived dogs, which correlated with ex vivo estimations of AT1 receptor numbers. Plasma renin activity, angiotensin II, and aldosterone were inversely related to changes in AT1 receptor binding. These results demonstrate, for the first time in vivo, that the renal AT1 receptor is inversely related to the activity of the renin angiotensin system, which may provide a compensatory mechanism to prevent inappropriate fluctuations in arterial BP. The ability to measure AT1 receptor binding in vivo has potential significance for clinical studies of AT1 receptors, because PET is a noninvasive imaging technique that is readily applicable in humans.