bluuebunny/crossref_metadata_2025 huggingface dataset:
Reference Typing Report for Complement Component C4
Authors: Mauff G. , Luther Birgit , Schneider P.M. , Rittner C. , Stradmann-Bellinghausen Beate , Dawkins R. , Moulds Joann M.
Published: April 2003

During the 7th Complement Genetics Workshop, Mainz, Germany, May 1998, a complement component C4 typing exercise took place with the aim of applying present technologies to the definition of reference C4 alleles/phenotypes and the recognition of nonexpressed (Q0) C4 alleles within expressed haplotypes. Eleven samples were submitted from 3 laboratories and tested by 14 participating laboratories with basic protein-typing technologies; in addition, each laboratory contributed data from local expertise. The samples were introduced to the reference typing for one or more characteristic allotype or for partial or total nonexpression of one isotype. The blinded samples were centrally evaluated and the results discussed among the participants at a plenum meeting. From the results, the samples could be classified into a group of common, easy to diagnose pheno-/allotypes, less common but still unanimously recognised variants, and a third group with difficult pheno-/allotypes. Within the latter group, the allotypes were either new (C4A ‘92’; C4B ‘93’) and/or showed partial or total reversed antigenicity and unusual Rodgers/Chido (Rg/Ch) PCR subtypes (C4A ‘92’; C4A 12; C4B ‘35’; C4B ‘13’). Semiquantitative C4-α-chain estimates of relative isotype levels correlated well with the number of alleles seen at each locus by agarose gel electrophoresis, and were superior to other isotype quantitation methods. From the evaluation of the reference typing it was concluded that the recognition of rare, aberrant or hybrid C4 alleles with partial or total reversed Rg/Ch antigenicity or monoclonal reactivity is still difficult in most instances; besides isotype-dependent lysis, relative migration values, immunoblots with Rg- and Ch-specific monoclonal antibodies, Rg/Ch PCR typing, side-by-side comparison with already described allotypes will ultimately be required. The recognition of nonexpressed alleles within C4A and C4B expressed phenotypes remains the major obstacle in C4 genetic typing. Finally, a conclusive interpretation of DNA typing results will be achieved only in the context of complete allotyping results at the protein level, and at present cannot replace conventional protein allotyping.
Reference Typing Reportfor Complement Component C3
Authors: Rittner C. , Bellavia D. , Geserick G. , Frank A. , Stradmann- B. , Bellinghausen B.
Published: April 2003

A comparison of five C3 variant samples has been performed by conventional high-voltage gel electrophoresis in three laboratories (Palermo, Berlin and Mainz). Local designation was shown within SD = ±0.75 mm migration distance in the Mainz laboratory. Methodological modifications by laboratories were not accounted for (cooling temperature, relative mobilities between runs). In parallel, all reference samples were also sequenced after exon-specific amplification. As a result, two variants with identical final designations and two variants with different mobilities were shown to conform at the molecular basis exhibiting an amino acid exchange that causes the corresponding change in relative mobility as compared to normal C3F and C3S.
Genetic Polymorphism of Human Complement Factor I (C3b Inactivator) in the Chinese Han Population
Authors: Zhang Lin , Stradmann-Bellinghausen Beate , Rittner Christian , Schneider Peter M.
Published: April 2003

The human complement factor I (IF) polymorphism has been analysed by polyacrylamide gel isoelectric focusing electrophoresis of neuraminidase-treated EDTA plasma samples followed by immunoblotting and enzymatic detection. In a population study among 121 random individuals from Chengdu, PR China, three different common phenotypes were observed. The results show that IF is polymorphic in the Chinese population. The allele frequencies were as follows: FI*A = 0.153, FI*B = 0.847. The distribution of observed phenotypes was in accordance with the Hardy-Weinberg equilibrium. In comparison to other Asian population studies, the frequency of the IF*A allele was the highest in the Chinese population studied here.
An Unequal Crossover between the RCCX Modules of the Human MHC Leading to the Presence of a CYP21B Gene and a Tenascin TNXB/TNXA-RP2 Recombinant between C4A and C4B Genes in a Patient with Juvenile Rheumatoid Arthritis
Authors: Rupert Kristi L. , Rennebohm Robert M. , Yu C. Yung
Published: April 2003

The RCCX module of the human MHC class III region is comprised of four genes arranged in tandem: RP, complement C4, steroid 21-hydroxylase (CYP21), and tenascin X (TNX). Variations in the number and genes of the RCCX modules may lead to genetic and/or autoimmune diseases. Restriction fragment length polymorphism (RFLP) analysis was utilized to determine the RCCX modular variation in patients with juvenile rheumatoid arthritis (JRA). In JRA patient L1, RFLP analysis suggested the presence of a bimodular RCCX structure containing both C4A long and C4B short genes, yet missing the markers for the CYP21A and TNXA genes usually located between the C4A and C4B genes. The 7.5-kb genomic fragment spanning the CYP21-TNX-RP2 genes was cloned and sequenced, revealing that a genetic recombination occurred between TNXA of a bimodular RCCX chromosome and TNXB of a monomodular RCCX chromosome. This recombination results in a new MHC haplotype with a CYP21B gene and a TNXB/TNXA-RP2 recombinant between the two C4 genes. Elucidation of the breakpoint region provides further evidence for the instability of the MHC class III gene region as a result of the RCCX modular variation.
Interleukin-15 Enhances HIV-1-Driven Polyclonal B-Cell Response in vitro
Authors: Kacani L. , Sprinzl G.M. , Erdei A. , Dierich M.P.
Published: April 2003

Interleukin-15 (IL-15) is a recently described cytokine, produced by monocytes/macrophages, with biological activities similar to IL-2. Since IL-15 was shown to stimulate human B-cell proliferation and immunoglobulin secretion, we investigated its effect on human B-cells stimulated with heat-inactivated human immunodeficiency virus type 1 (iHIV-1) in vitro. We observed a dose-dependent elevation of [3H]-thymidine incorporation and immunoglobulin production by B-cells incubated in the presence of iHIV-1. Moreover, IL-15 stimulated HIV-1-driven B-cell proliferation similarly to IL-2. As to immunoglobulin secretion, IL-15 was able to potentiate the stimulatory effect of IL-10. The highest amounts of iHIV caused a decrease in B-cell proliferation and immunoglobulin secretion to baseline levels, even in the presence of cytokines. These findings indicate that during the late stages of AIDS, when monocytes/macrophages become the major site of viral production, IL-15, in concert with other monocyte-derived cytokines, may promote polyclonal B-cell activation and hypergammaglobulinaemia, which are frequently associated with HIV infection.
Analysis of Immunoglobulin VH and TCR Cβ Polymorphisms in a Large Family with Thyroid Autoimmune Disorder
Authors: Fakhfakh F. , Maalej A. , Makni H. , Abid M. , Jouida J. , Zouali M. , Ayadi H.
Published: April 2003

In order to investigate the association of TCR Cβ and immunoglobulin (Ig) VH polymorphisms with thyroid autoimmune diseases (TAD), we analyzed restriction-endonuclease-generated polymorphisms using T-cell receptor (TCR) Cβ and VH gene-family-specific probes. We tested genomic DNAs of patients isolated from a large family affected with Graves’ disease and Hashimoto’s thyroiditis as well as the genomic DNA of unrelated Tunisian controls. Hybridization of BglII-digested DNA with a TCR Cβ probe revealed two alleles of 9.2 and 10 kb. These Cβ polymorphisms have already been found in the Caucasian population. However, there was no abnormal distribution of this polymorphism in patients with TAD, compared to related healthy individuals and to unrelated Tunisian controls. Besides, there was a low VH polymorphism in members of the family affected with TAD. Analysis of the Ig gene families revealed no restriction site polymorphism pattern specific for TAD.
Complement Component C6 Polymorphism: Novel Protein-Typing Technique and Distribution of Allotypes in Germany
Authors: Schwarzenholz Björn , Correns Andreas , Schröder Helga , Geserick Gunther
Published: April 2003

The genetic polymorphism of human C6 was investigated in Germany using an improved technique: polyacrylamide gel isoelectric focusing and subsequent direct immunofixation with monospecific C6 antisera. Typing of C6 was performed on native serum samples from 1,775 unrelated persons. The gene frequencies in the population study were as follows: C6*A 0.6313, C6*B 0.3566 and the rare alleles C6*R 0.0121. In total, 8 rare allotypes were analysed. The gene frequencies obtained are in good agreement with those previously published.
Two Human Gene Families Display Preferences for Different Nucleotides and Have Distinct Codon Usage Patterns
Authors: Skerka Christine , Abel Wolfgang O. , Zipfel Peter F.
Published: April 2003

Analysis of base composition has proven important for functional gene analysis. By comparing base composition and codon usage between two specific human gene families we were able to show a highly conserved nucleotide distribution among the members of one gene family and a significant difference between the two families. The two groups selected for analysis were the human factor H gene family, which represents six secreted human plasma proteins with functions in immune defense, and a class of four human zinc finger proteins, termed early growth response (EGR) proteins, which represent DNA-binding transcription factors. The nucleotide distribution of each gene family is distinct: members of the factor H gene family represent AT-rich genes, displaying an overall AT nucleotide content of 62.8% and a particular preference for A nucleotides (33.9%). In contrast, the EGR genes are GC-rich (55.9%) and C nucleotides are used in 31.2%. This nucleotide difference affects codon usage among synonymous codons and is considered of biological significance, as it affects DNA stability. The codon preference is particularly high at codon position 3, where each family selects for codons which have the preferred nucleotide at this silent third position. At position 3, A nucleotides are preferred by factor H genes in 36.3% of the 2,503 codons analyzed, compared to 10% of the 1,876 codons analyzed for the EGR family. In contrast, C nucleotides are used by the EGR family in 48.1%, compared to 16% of the triplets used by the factor H gene family. This comparison of two human gene families shows that nucleotide distribution and codon usage is not uniform within the human organism and the described differences most likely represent selection constraints between the polymorphic factor H and highly conserved EGR genes.
Prevention of Renal Injury in Diabetic MWF Rats by Angiotensin II Antagonism
Authors: Remuzzi Andrea , Fassi Annamaria , Sangalli Fabio , Malanchini Barbara , Mohamed Ehab I. , Bertani Tullio , Remuzzi Giuseppe
Published: April 2003

We studied the effect of the combination of streptozotocin-induced diabetes and spontaneous renal injury in male MWF rats. Renal hemodynamics was studied by micropuncture 1 month after streptozotocin administration, and kidney morphological evaluation was performed after 4 months of diabetes. We also studied the effect of angiotensin II antagonism on development of renal lesions. Untreated animals developed mild hypertension, proteinuria, and glomerulosclerosis. Induction of diabetes, and maintenance of a moderate hyperglycemic state, was associated with slight but significant elevation in systemic and glomerular capillary blood pressure. Development of proteinuria was not accelerated or exacerbated by diabetes. Glomerular and tubular structural changes were also not worsened by diabetes. Antihypertensive treatment with an ACE inhibitor (benazepril) or with an AII receptor antagonist (valsartan) almost completely prevented systemic and glomerular capillary hypertension, proteinuria and renal structural changes. No significant differences in glomerular volume were observed among the four groups. That induction of experimental diabetes, although associated with glomerular capillary hypertension, did not aggravate the rate of progression of renal dysfunction would suggest that glomerular injury is not directly influenced by glomerular hemodynamic conditions in these animals. Prevention of renal functional and structural abnormalities by antagonism of AII activity in diabetic MWF rats suggests a pathogenetic role for angiotensin in inducing the renal disease in these animals.
Beneficial Effect of the Long-Term Treatment with the Combination of an ACE Inhibitor and a Calcium Channel Blocker on Renal Injury in Rats with 5/6 Nephrectomy
Authors: Flores Olga , Arévalo Miguel , Gallego Belén , Hidalgo Froilán , Vidal Sebastián , López-Novoa José M.
Published: April 2003

The effects of the addition of a calcium channel blocker, verapamil (20 mg/kg/day) to an ACE inhibitor, trandolapril (0.7 mg/kg/day) in a 6-month treatment on renal insufficiency development in rats with 5/6th nephrectomy, were studied. Every month we measured heart rate and arterial pressure by the tail-cuff method. Renal function studies were performed in metabolic cages. At the end of the study, renal tissue was prepared for light microscope analysis. Renal lesions were assessed by semiquantitative scores in a blind fashion. Corpuscular section area, intraglomerular and tubulointerstitial fibrosis were determined by digital image analysis with a specific software (Fibrosis HR®) on syrium red-stained renal sections. Trandolapril markedly increased the survival ratio that after 6 months reached 87% in comparison with 61% in untreated rats. No mortality was observed in rats treated with the combination of verapamil and trandolapril. Trandolapril treatment prevented the development of hypertension. The combination verapamil-trandolapril did not induce further reduction on blood pressure. The untreated group showed a marked proteinuria, that in the trandolapril group showed an important reduction. The verapamil + trandolapril group showed a proteinuria significantly smaller than that of all the other groups. Light microscopy semiquantitative studies of the renal injury showed that the trandolapril and verapamil + trandolapril groups had a marked reduction in glomerular and tubulointerstitial alterations, compared with untreated animals. Quantitative determinations of glomerular and interstitial fibrosis performed on syrium red-stained renal sections demonstrated that fibrosis was reduced when rats when treated with trandolapril and even more with verapamil + trandolapril when they were compared to untreated animals’ values. In conclusion, long-term treatment with verapamil given in addition to trandolapril produces additional protection against progressive renal injury associated to subtotal nephrectomy.
Tubular Epithelial Cells as Accessory Cells for Superantigen-Induced T Cell Activation
Authors: Schulz Holger , Karau Antje , Filsinger Sabine , Schoels Margarita , Kabelitz Dieter , Richter Rosi , Hänsch G. Maria
Published: April 2003

In various inflammatory kidney diseases, tubular epithelial cells (TEC) express major histocompatibility complex class II antigens. To assess whether they might have the capacity to directly activate T cells, human TEC in culture were treated with gamma interferon to induce class II expression. TEC were then cocultivated with staphylococcus enterotoxin and cloned T cells or highly purified peripheral T cells. After 1–2 days, release of interleukin 2 and of gamma interferon was seen; after 3–5 days T cell proliferation occurred. The proliferation could be inhibited by antibodies to class II antigens or by antibodies to ICAM-1; the latter is also expressed on TEC in inflammatory processes and on TEC in culture as well. In conclusion, human TEC might function as accessory cells for T cell activation and might support T cell dependent immune response.
Differential Response of Activated versus Non-Activated Renal Fibroblasts to Tubular Epithelial Cells: A Model of Initiation and Progression of Fibrosis?
Authors: Lewis Mark P. , Norman Jill T.
Published: April 2003

Background/Aims: The mechanisms of initiation and maintenance of renal fibrosis remain obscure, but one hypothesis highlights the importance of tubular epithelial cell-interstitial fibroblast interactions and suggests that tubular injury may be a precipitating factor. The aims of the study were to examine the effects of factors of proximal tubular origin on renal fibroblasts expressing different levels of smooth muscle actin (SMA; a putative marker of fibroblast activation) and to examine the modulation of SMA by extracellular matrix (ECM) proteins and transforming growth factor beta 1 (TGF-β1), a major profibrotic cytokine. Methods: Primary cultures of rat cortical fibroblasts (CF) and the rat kidney fibroblast cell line NRK-49F were (1) cultured on different ECM proteins; (2) treated with medium conditioned by rat proximal tubular epithelial cells (PTE), and (3) treated with TGF-β1. SMA protein expression was examined by immunocytochemistry, while expression of MMP-2, MMP-3, TIMP-1, and collagen I mRNA was determined by Northern blot analysis or reverse-transcriptase polymerase chain reaction. Results: In cells with low basal levels of SMA (CF), serum was the most potent inducer of increased SMA expression, although ECM proteins also modulated expression. With high basal levels of SMA expression (NRK), ECM proteins alone had little or no effect, but acted synergistically with serum to stimulate expression. In CF, PTE-conditioned medium (CM) had no effect on SMA and TIMP mRNA levels, but suppressed expression of MMP mRNAs. In NRK-49F, PTE-CM stimulated SMA and TIMP-1 mRNA levels, but had no effect on MMP mRNA levels. Although TGF-β1 modulated some cellular responses in NRK-49F, neutralizing antibody studies showed it was not the main mediator of the PTE-CM-induced effects. Conclusions: These data suggest (1) that in renal fibroblasts SMA expression can be modulated by both serum and ECM proteins and (2) that PTE induce a fibrogenic phenotype in both non-activated (low SMA) and activated (high SMA) fibroblasts via different mechanisms.
The HVJ Liposome Method
Authors: Isaka Yoshitaka , Akagi Yoshitaka , Kaneda Yasufumi , Imai Enyu
Published: April 2003

Recent advancement of gene technology allows us a practical approach to gene therapy. Among various in vivo gene transfer techniques available, the HVJ liposome method is an efficient procedure which could target the glomerular cells. Using this method, HVJ-mediated cell fusion activity enables us to introduce genetic materials directly into the cytosol without degradation. In addition, cointroduction of non-histone nuclear protein, high-mobility group (HMG-1), efficiently facilitates migration of foreign DNA to the nucleus. Although there still exist some limitations, the HVJ liposome method may be applicable to the treatment of glomerular diseases as well as to analysis of the molecular aspects of renal pathophysiology.
The Calcium Receptor in Health and Disease
Authors: Hory Bernard , Roussanne Marie-Cécile , Drüeke Tilman B. , Bourdeau Agnès
Published: April 2003

The recent cloning of a G-protein-coupled, extracellular calcium [(Ca2+)e]-sensing receptor (CaRG) from the parathyroid, kidney and brain of several species has clarified the molecular mechanisms underlying Ca2+-sensing by parathyroid and other cell types. It has long been suspected that such a receptor existed on parathyroid cells, coupled to intracellular second messengers through guanine nucleotide regulatory (G) protein which is able to recognize and respond to (Ca2+)e. Recently, functional screening of a cDNA library constructed from bovine parathyroid mRNA led to the isolation of a 5.3-kb clone expressing maximal Ca2+-stimulated Cl– currents in oocytes. This 5.3-kb cDNA encodes a protein of 1,085 amino acids with three principal predicted structural domains. The CaRG protein is present in chief parathyroid cells, in C cells of the thyroid, in the cortical thick ascending limb (TAL) and collecting duct of the kidney, and in discrete brain areas. CaRG may play several physiological roles. It is a central element in the control of both parathyroid and calcitonin secretion by (Ca2+)e. Moreover, functional evidence for its participation in the regulation of renal Ca2+ reabsorption in TAL and water reabsorption in the collecting duct has been obtained. Mutations of the CaRG gene are responsible for hereditary and familial parathyroid disorders, and a decrease in CaRG expression has been documented in primary and secondary uremic hyperparathyroidism. The expression of CaRG in several additional organs and tissues allows speculation on the potential involvement in other pathologies.
The Renal TGF-β System in the db/db Mouse Model of Diabetic Nephropathy
Authors: Cohen Margo P. , Sharma Kumar , Guo Jia , Eltayeb Babiker O. , Ziyadeh Fuad N.
Published: April 2003

The prosclerotic cytokine transforming growth factor beta 1 (TGF-β1) has been causally implicated in renal pathobiology in diabetes. We sought evidence that the TGF-β system participates in the nephropathic process in the db/db mouse, a hyperinsulinemic model of genetic diabetes that develops abnormalities in renal morphology and function that parallel those in human diabetic nephropathy. In support of this hypothesis, we found that steady state levels of mRNA encoding the TGF-β type II receptor were significantly increased in renal cortex from db/db diabetic mice. Additionally, the translated TGF-β type II receptor protein, assessed by immunoblot, also was increased in diabetic kidneys. However, in contrast to rodents with insulin-deficient diabetes, steady state levels of mRNA encoding TGF-β1 in the renal cortex of diabetic db/db mice did not differ from those in cortex from nondiabetic (db/m) littermate controls. Further, concentrations of TGF-β protein, measured by immunoassay and bioassay, were significantly lower in extracts prepared from renal cortex of diabetic animals compared with those from nondiabetic controls. Urine and serum concentrations of immunoreactive TGF-β1 also were reduced in diabetic mice. The findings are consistent with upregulation of TGF-β type II receptor activity as a consequence of hyperglycemia in the hyperinsulinemic db/db mouse and suggest that hyperinsulinemia inhibits TGF-β1 production. The results further suggest that type II receptor upregulation is a contributing factor to the increased gene expression of renal cortical mRNAs encoding the extracellular matrix proteins fibronectin and alpha 1 (IV) collagen and to the renal abnormalities observed in this animal model.
Expression of Id-1 mRNA and Protein in the Post-Ischemic Regenerating Rat Kidney
Authors: Matejka Göran L. , Thornemo Maria , Kernholt Annika , Lindahl Anders
Published: April 2003

The basic helix-loop-helix (bHLH) class of proteins are of major importance in controlling tissue-specific gene expression. The actions of the bHLH proteins are inhibited by a related class of proteins, inhibitors of differentiation (Id). We have studied the expression of one of these latter proteins, Id-1, in the normal and post-ischemic regenerating rat kidney by immunocytochemistry, Western blot and RNase protection assay (RPA) and correlated Id-1 regulation to the expression of vimentin and proliferating cellular nuclear antigen (PCNA). In the normal kidney strong immunostaining for Id-1 was found in the distal nephron, especially in the distal convoluted tubule in the cortex. In particular, the perinuclear region was intensely stained in the cells of the distal tubule. mRNA for Id-1 was detectable by RPA on total RNA extracted from the renal cortex of sham-operated animals. The Id-1 monomer was detected on Western blots of normal animals. Vimentin was expressed in the mesangial cells of the glomeruli and in cells in the interstitium while tubule cells were negative. The labeling intensity for PCNA was low in all cellular compartments in the normal kidney. In the regenerating kidneys at various time intervals, the expression of Id-1-like immunoreactivity was widespread in the regenerating dedifferentiated tubule cells while by the end of the study period, more highly differentiated tubule cells appeared to lose their staining. On Western blots the Id-1 monomer was undetectable and instead strong staining was seen in the high molecular range. Id-1 mRNA levels in the regenerating kidneys did not differ significantly when compared to sham. PCNA labeling was intense in the regenerating kidneys at all time periods studied, indicating the intense proliferative activity in the regenerating kidneys. Vimentin expression in the renal tubule cells was increased from day 3 and onward. The data are consistent with a hypothesis in which Id-1 regulates differentiation of renal tubule cells in the post-ischemic regenerating rat kidney.
Regulation of Phosphate Transport in the Renal Tubule through Parathyroid Hormone Receptor: Unexpected Pathways
Authors: Silve Caroline , Friedlander Gérard
Published: April 2003

The recent molecular identification of parathyroid hormone (PTH) receptors, on the one hand, and Napi cotransporters, on the other hand, has enabled the development of powerful tools to boost the study of the regulation of renal Pi transport by PTH, a regulation which stands at a crucial point in the physiology and pathophysiology of Pi homeostasis. The aim of this review is to summarize these recent findings.
Scintigraphic Imaging of Renal Function
Authors: Peters A.M.
Published: April 2003

Scintigraphic imaging of renal phyisology can be achieved by gamma camera planar imaging, single photon emission computerised tomography (SPECT) or positron emission tomography (PET). Physiological information about the kidney usually requires dynamic imaging, although for some applications imaging may be static. Individual kidney renal blood flow can be measured from dynamic gamma camera imaging, although with PET it is possible to measure regional renal perfusion. Measurement of individual kidney glomerular filtration rate (GFR) is performed routinely with Tc-99m-diethylene triamine pentaacetic acid (DTPA), but information about GFR on a regional basis, and measurement of regional filtration fraction, require PET. Manoeuvres which interfere with renal physiology, such as captopril renography, may also yield useful diagnostic information.
Ultramicroanalysis of Peptide Profiles in Biological Samples Using MALDI Mass Spectrometry
Authors: Jiménez Connie R. , Burlingame Alma L.
Published: April 2003

In the past few years, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has emerged as a powerful tool for the direct analysis of peptide profiles contained in single neuroendocrine cells, tissue biopsies, as well as in releasates (after a simple sample clean-up). These studies were performed in both invertebrate (the pond snail) and vertebrate (xenopus and rat) species. The present article provides an overview of these data with a special emphasis on the sample handling required for each application.
Molecular Interactions between Albumin and Proximal Tubular Cells
Authors: Brunskill Nigel J.
Published: April 2003

In glomerular diseases the filtration of excess proteins into the proximal tubule, together with their subsequent reabsorption may represent an important pathological mechanism underlying progressive renal scarring. The most prominent protein in glomerular filtrate, albumin, is reabsorbed by receptor-mediated endocytosis by proximal tubular cells. It binds both to scavenger-type receptors and to megalin in the proximal tubule. Some of these receptors appear to be shared with other cell types, particularly endothelial cells. The endocytic uptake of albumin is subjected to complex hormonal and enzymatic regulation. In addition to being reabsorbed in the proximal tubule, albumin may act as a signalling molecule in these cells, and may induce the expression of numerous pro-inflammatory genes. Modulation of the interaction of albumin with proximal tubular cells may eventually prove to be of therapeutic importance in the treatment of renal diseases.
Regulation of Tissue Plasminogen Activator Production in Cultured Human Fetal Mesangial Cells
Authors: Yoshiko Baba , Yamabe Hideaki , Osawa Hiroshi , Okumura Ken
Published: April 2003

Glomerular fibrin deposition is thought to be one of the factors causing progressive glomerular injury and may be related to defective intraglomerular fibrinolysis. Recently, it was shown that tissue plasminogen activator (t-PA) is produced by mesangial cells and is associated with degradation of the extracellular matrix. This study was designed to clarify the factors regulating t-PA production in human mesangial cells. The levels of t-PA activity, t-PA antigen and t-PA inhibitor-1 (PAI-1) antigen were estimated in the supernatants of cultured human fetal mesangial cells incubated for 72 h with thrombin, IL-Iβ, IL-6, IL-10, and transforming growth factor-β (TGF-β). The t-PA activity was measured by an amidolytic assay, and the levels of t-PA antigen and PAI-1 antigen were also measured by enzyme-linked immunosorbent assay. Thrombin increased t-PA activity and TGF-β decreased it in parallel with t-PA antigen level, although these agents did not affect the synthesis of PAI-1. Incubation with IL-1β, IL-6 and IL-10 did not change the t-PA activity. It was concluded that the release of t-PA from human fetal mesangial cells was stimulated by thrombin and inhibited by TGF-β in parallel with that of t-PA antigen. These factors may participate in the glomerular fibrin deposition and the accumulation of extracellular matrix.
Expression of Fetal Kidney Growth Factors in a Kidney Tumor Line: Role of FGF2 in Kidney Development
Authors: Drummond Iain A. , Mukhopadhyay Debabrata , Sukhatme Vikas P.
Published: April 2003

To identify growth factors which may play a role in kidney organogenesis, we have analyzed culture supernatants from the pediatric kidney tumor cell line G401. G401 cells were found to secrete fibroblast growth factor 2 (FGF2), a potent mitogen for mesenchymal cells, OP-1/BMP7, an epithelial cell growth inhibitor, and midkine (MK). Northern blotting confirmed expression of FGF2, OP-1/BMP7 and MK mRNA, as well as Wnt5A mRNA in G401 cells. In situ hybridization and immunocytochemistry on human fetal kidney demonstrated FGF2 expression in epithelial cells of the branching ureteric bud epithelium, nephron precursors (‘S-shaped bodies’), proximal tubule epithelium and the parietal epithelium of the glomerulus. FGF2 protein in condensed ‘caps’ of induced mesenchymal cells was also detected by immunocytochemistry. FGF2 protein was found to be concentrated in nuclei, particularly in proximal tubule epithelial cells. Recombinant FGF2 was found to act as a mitogen on primary mouse fetal kidney cell cultures. The results demonstrate G401 cells secrete a variety of fetal kidney growth factors and that FGF2 may act as a mitogen for fetal kidney cells and thus could play a role in the morphogenesis of the kidney.
Metabolic Rates of 4-Hydroxynonenal in Tubular and Mesangial Cells of the Kidney
Authors: Petras Tobias , Siems Werner , Henke Wolfgang , Jung Klaus , Olbricht ChristophJ. , Gwinner Wilfried , Grune Tilman
Published: April 2003

The degradation of the lipid peroxidation product 4-hydroxynonenal (HNE) in primary cultures of kidney tubular and mesangial cells was determined. Using various initial concentrations of the aldehyde a decline of cellular viability was found. Mesangial cells were more susceptible to the toxic effects of HNE. In consumption studies of HNE the decline of the exogenously added aldehyde was comparable in both cell types after addition of 10 and 1 µmol HNE/l. After addition of 100 µmol/l aldehyde a drastically lower HNE degrading capacity was found in mesangial cells as compared to tubular cells. The loss in the HNE degrading capacity was accompanied by an increased formation of HNE-protein aggregates as demonstrated by immunoblots. Therefore, we concluded that the low ability of mesangial cells to degrade HNE may be a factor of the toxicity of free radicals on the kidney.
Cell Adhesion Molecules in the Kidney: From Embryo to Adult
Authors: Perantoni Alan O.
Published: April 2003

Multiple members from every major family of cell adhesion molecules (CAMs) have been implicated in the development, maintenance, or repair of renal tissues and include several isoforms of integrins, cell-bound glycoproteins, cadherins, immunoglobulin cell adhesion molecules, and selectins. In combination, they mediate a variety of cell-basement membrane and cell-cell interactions believed to direct morphogenesis and cell migration and regulate cell growth and apoptosis, in addition to generating a functional barrier for blood filtration and helping manage inflammatory responses in the kidney. The expression of some CAMs is transient during and critical to normal nephrogenesis, varying with specific stages of development, but often ultimately resulting in the constitutive production of other members in mature tissues. While gene-targeting studies have successfully implicated individual CAMs in renal cell functions, e.g., α3β1 and α8β1 integrins, the loss of others bears no renal phenotype due to redundancy of homologous family members or to the severity of the defect early in embryogenesis. This review summarizes the studies of various CAMs found in normal embryonic or adult kidney, describes their spatiotemporal expression patterns, and discusses their involvement in renal processes.
Parathyroid Hormone-Related Protein: Roles in the Glomerulus
Authors: Bosch Ricardo J. , Rodríguez-Puyol Diego , Bover Jordi , Rodríguez-Puyol Manuel
Published: April 2003

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) produce similar biological effects through the PTH/PTHrP receptor. Less is known about the physiological role of PTHrP which was first identified as the agent of the humoral hypercalcemia of malignancy. Despite the widespread production of PTHrP in healthy individuals, the concentration of the protein is below the detectable limit of current assays, suggesting that PTHrP normally functions locally in an autocrine or paracrine manner. Thus, some differences in their biological activities have been described, and they may be related to the presence of different receptors. In this regard, a second receptor which binds selectively to PTH has also been found. Recent studies have demonstrated the expression of both PTH/PTHrP receptor and protein in the renal glomeruli. Moreover, there are convincing data that support a direct role of PTH and PTHrP in modulating renal blood flow and glomerular filtration rate. This multifunctional protein, PTHrP, also has a proliferative effect on mesangial cells, supporting the notion that it may play a role in the normal glomerulus and in injured kidney.
Inhibition of Erythrocyte Aminolevulinate Dehydratase by a 56.2-kD Peptide from Uremic Plasma
Authors: Guolo Marcelo , Machalinski Claudia , Biscoglio Mirtha , Stella Ana Maria , Franco Carlos , Pataro Luis , de Salamanca Rafael Enriquez , Batlle Alcira
Published: April 2003

Among the abnormalities in erythrocyte porphyrin metabolism already described in patients with chronic renal failure on hemodialysis, a decrease in blood aminolevulinate dehydratase activity has been reported, suggesting the presence in uremic plasma of an inhibitor of the enzyme. The aim of this work has been to isolate and characterize such an inhibitor. Blood samples from 105 patients with chronic uremia were collected; plasma was applied to Sephadex G-100 columns and the fraction with the highest inhibiting capacity was identified and purified by subsequent SDS-polyacrylamide gel electrophoresis, followed by electroelution and electroblotting. It was demonstrated that the factor present in plasma of uremic patients inhibited blood aminolevulinate dehydratase in a concentration-dependent manner; its inhibitory properties were abolished after heat, trypsin and TCA treatment indicating its peptidic nature. The purified inhibitor has an apparent molecular mass of 56.2 kD, it inhibits blood aminolevulinate dehydratase in a competitive way and the Ki value is 12×10–6 M. The amino acid composition of the inhibitor has been determined and it has been found that its N-terminal amino acid is blocked. The isolated peptide may play a role in heme biosynthesis disturbances and in the pathogenesis of uremic anemia.
Regulation of Dopamine-Induced Natriuresisby the Dopamine-Metabolizing Enzyme Catechol-O-Methyltransferase
Authors: Odlind Cecilia , Göransson Viktoria , Reenilä Ilkka , Hansell Peter
Published: April 2003

Dopamine (DA) is an intrarenal natriuretic hormone involved in sodium homeostasis. A study was performed to elucidate two possible regulatory pathways of DA-induced natriuresis, i.e., metabolism and precursor delivery. This was done by use of an intraperitoneal injection of a catechol-O-methyltransferase (COMT) inhibitor, entacapone, or intravenous infusion of the DA precursor, L-dopa. Entacapone (30 mg/kg i.p.) induced a more than fivefold increase in renal sodium excrection which occurred without changes in renal haemodynamics. The natriuretic response was highly dependent on DA D1-like receptor activation, since the selective D1-like receptor antagonist SCH23390 attenuated the natriuretic response by 61%, while the selective D2-like receptor antagonist sulpiride was ineffective. The urinary excretion of DA did not increase. Infusion of L-dopa (60 μg/h/kg) only induced a twofold increase in sodium excretion, but the urinary excretion of DA increased more than 17-fold. The L-dopa-induced natriuretic response occurred without increments in glomerular filtration rate and could be blocked with the D1-like receptor antagonist SCH23390. It is concluded that the DA-metabolizing enzyme COMT is involved in the regulation of the natriuretic effect of intrarenal DA. It may be speculated that intrarenal DA activity is not primarily determined on the basis of delivered precursor, but on that of the level of DA metabolism.
L-Histidinol Attenuates Fanconi Syndrome Induced by Ifosfamide in Rats
Authors: Badary Osama A.
Published: April 2003

The effect of L-histidinol (LHL), a structural analogue of the essential amino acid L-histidine, on ifosfamide (IFO) induced nephrotoxicity was investigated in the rat. The aim of this study was to assess whether oral supplementation of LHL could attenuate Fanconi syndrome (FS) induced by IFO. Male Wistar albino rats received daily injections of IFO (50 mg/kg) for 5 days with or without oral supplementation of 0.5% LHL in the drinking water. LHL was supplemented for 3 days before IFO administration and daily thereafter. Control rats were injected with saline with or without oral LHL. The results demonstrated that IFO induces a FS characterized by wasting of glucose, electrolytes, and organic acids, along with elevated serum creatinine and urea levels and decreased creatinine clearance. IFO-induced FS was associated with significant renal nonprotein sulfhydryl depletion and lipid peroxide (malondialdehyde) accumulation. LHL strongly ameliorated the severity of renal dysfunction induced by IFO, with significant decreases in total and fractional excretions of Na+, K+, PO43–, and glucose. Also, LHL significantly decreased the elevated serum creatinine and urea levels and significantly increased the creatinine clearance. Moreover, the beneficial effects of LHL were associated with a significant improvement of IFO-induced nonprotein sufhydry depletion and lipid peroxide accumulation. These results demonstrate that oral supplementation of LHL can partially protect against IFO-induced FS in rats.
Tubular Epithelial Cells: A Critical Cell Type in the Regulation of Renal Inflammatory Processes
Authors: van Kooten Cees , Daha Mohamed R. , van Es Leendert A.
Published: April 2003

Most chronic human kidney diseases are characterized by a final common pathway consisting of interstitial inflammation and ultimately leading to interstitial fibrosis. Within this process, tubular epithelial cells (TECs) play a critical role. Both in vitro and in vivo it has been demonstrated that TECs are an important source of various cytokines, chemokines, growth factors, adhesion molecules and extracellular matrix components. In the present review we will outline the capacity of TECs to produce inflammatory mediators and discuss the different mechanisms involved in the regulation of production of these mediators.
Decreased Degradation of Collagen and Fibronectin following Exposure of Proximal Cells to Glucose
Authors: Phillips Aled O. , Morrisey Kimberley , Steadman Robert , Williams John D.
Published: April 2003

Background/Aims: Thickening and reduplication of the tubular basement membrane has been reported as an early event in diabetic nephropathy. The aim of the work outlined here was to examine the effects and mechanisms involved in the modulation of renal proximal tubular type-IV collagen and fibronectin turnover by glucose. Methods: The effect of glucose on type-IV collagen and fibronectin generation was studied by exposure of primary cultures of human renal proximal tubular cells (HPTC) to elevated D-glucose concentrations. Subsequently the mechanism of modulation of fibronectin generation was examined in a polarised system utilising the porcine proximal tubular cell line LLC-PK1 grown on porous tissue culture inserts. Results: Incubation of confluent growth-arrested HPTC with 25 mM D-glucose led to the accumulation of both type-IV collagen and fibronectin. This increase was not dependent on new gene transcription for either protein. Exposure of HPTC to 25 mM D-glucose also led to the induction of tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) and also gelatinase A. There was, however, a net decrease in overall gelatinolytic activity. Incubation of confluent monolayers of LLC-PK1 cells grown on tissue culture inserts with 25 mM D-glucose on either their apical or basolateral aspect led to fibronectin accumulation seen only in the basolateral compartment. Under these experimental conditions, we can demonstrate polyol pathway activation, and furthermore the increase in fibronectin concentration in response to glucose was inhibited by the aldose reductase inhibitor sorbinil. Fibronectin accumulation was also demonstrated following both apical and basolateral addition of 1 mM sorbitol, but not following the addition of 25 mM galactose to either aspect of the cells. Conclusions: These data demonstrate that the glucose-induced accumulation of type-IV collagen and fibronectin was associated with alterations in the degradative pathway of these matrix components. In addition fibronectin generation in response to glucose was non-polar in terms of application of glucose, but polar in terms of fibronectin accumulation. The mechanisms of glucose-induced modulation of fibronectin were mediated by polyol pathway activation, and more specifically related to the metabolism of sorbitol to fructose.
Isolation, Culture and Characterization of Human Renal Proximal Tubule and Collecting Duct Cells
Authors: Trifillis Anna L.
Published: April 2003

The complexity and heterogeneity of the human nephron with regard to cell types make well-defined in vitro systems of renal cells valuable for studies of the pathogenetic mechanisms involved in nephrotoxicity. In our laboratory renal proximal tubule cells (PTC) and collecting duct cells (CDC) have been isolated, cultured and characterized from cadaver kidneys (postmortem time <24 h) for use in studies of renal cytotoxicity induced by therapeutics and bacteria. PTC seeded at 106 cells/ml formed confluent monolayers within 7 days. Histochemical markers were used to determine the origin of the cell cultures. Cells were negative for factor VIII, positive for cytokeratin and γ-glutamyltransferase (GGT), and bound winged pea lectin. CDC, isolated from the renal papillae, formed monolayers within 14 days of seeding. CDC were negative for factor VIII and GGT, positive for cytokeratin and bound peanut lectin. PTC and CDC isolates and cultures exhibited typical epithelial cell ultrastructure: cell junctions, intermediate filaments, microvilli, and numerous mitochondria. The morphological and histochemical evidence confirms that PTC and CDC can be isolated and cultured for use in in vitro studies.
Immortalized Kidney Cells Derived from Transgenic Mice Harboring L-Type Pyruvate Kinase and Vimentin Promoters
Authors: Vandewalle A.
Published: April 2003

Targeted oncogenesis in transgenic mice, where an oncogene is placed under the control of the regulatory sequences of a cell-specific gene, has been used to derive several new types of differentiated nonepithelial and epithelial cell lines. This review summarizes the properties of cell lines derived from proximal, distal and collecting duct cells. The cells were obtained from kidneys of transgenic mice harboring the 5′ regulatory sequences of the L-type pyruvate kinase or vimentin genes controlling the expression of either the large T and little t antigens or the temperature-sensitive large T antigen.
Modulation of Cell Differentiation in Perfusion Culture
Authors: Minuth Will W. , Steiner Pat , Strehl Raimund , Schumacher Karl , de Vries Uwe , Kloth Sabine
Published: April 2003

An in vitro model was used to investigate the terminal differentiation mechanisms leading from embryonic to adult renal tissue. For these experiments the capsula fibrosa with adherent embryonic tissue was isolated from neonatal rabbit kidneys. These explants were mounted onto special tissue carriers and cultured in medium containing serum for 24 h. During that time collecting duct (CD) cells grew out and formed a monolayered epithelium covering the whole surface of the explant. The carriers were then transferred to perfusion culture containers to obtain an optimal degree of differentiation. A special type of container allowed us to continuously superfuse the epithelia with individual media on the luminal and basal sides. Using this method it became possible to culture embryonic CD epithelia in a fluid gradient for weeks. The epithelia were superfused with standard Iscove’s modified Dulbecco’s medium (IMDM) on the basal side, while IMDM containing additional NaCl was used on the luminal side. In controls IMDM was superfused on both the luminal and basal sides. It was found that the degree of differentiation in the CD epithelia is dependent on the influence of fluid gradient exposure. Perfusion culture under isotonic conditions revealed that less than 5% of cells were immunopositive for principal and intercalated cell features, while epithelia cultured in a luminal-basal gradient showed more than 80% positive cells. Immunoreactivity for characteristic markers started to develop after an unexpectedly long latent period of 3–6 days, then increased continuously during the following 5 days and reached a maximum on day 14. After switching back from the gradient to isotonic culture conditions the immunoreactivity for some markers decreased within 5 days, while other characteristic features remained stable. Thus, differentiation was not only under the control of growth factors but was also regulated by the electrolyte environment.
Antisense and Kidney Cell Research
Authors: Ganz Michael B.
Published: April 2003

Antisense oligodeoxynucleotides offer the potential to block the expression of specific genes with the goal of altering the phenotypic behavior of the cell. Antisense technology has attracted special interest as potential therapeutic agents for the treatment of genetic disorders, viral infections, and most recently proliferative diseases such as glomerular kidney disease. This technique has recently been used for in vitro and in vivo studies in renal cells. The use of antisense technology has been applied in vitro to help define both the normal mechanisms of specific ion transport and function and the pathobiological processes leading to glomerular proliferation and matrix formation. Most promising are the recent uses of antisense technology in vivo that have been used to treat the damaged peritoneum and alter glomerular remodeling in experimental animal models. It is hoped that widespread use of antisense will not only provide new insight into the normal regulatory behavior of the kidney cells but also allow one to develop therapeutic strategies to treat kidney disease.