bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

<b>Background/Aims:</b> 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-β<sub>1</sub>), a major profibrotic cytokine. <b>Methods:</b> 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-β<sub>1</sub>. 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. <b>Results:</b> 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-β<sub>1</sub> modulated some cellular responses in NRK-49F, neutralizing antibody studies showed it was not the main mediator of the PTE-CM-induced effects. <b>Conclusions:</b> 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 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-β<sub>1</sub>) has been causally implicated in renal pathobiology in diabetes. We sought evidence that the TGF-β system participates in the nephropathic process in the <i>db/db</i> 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 <i>db/db</i> 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-β<sub>1</sub> in the renal cortex of diabetic <i>db/db</i> mice did not differ from those in cortex from nondiabetic <i>(db/m)</i> 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-β<sub>1</sub> 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 <i>db/db</i> mouse and suggest that hyperinsulinemia inhibits TGF-β<sub>1</sub> 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.
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.
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, <i>L</i>-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 D<sub>1</sub>-like receptor activation, since the selective D<sub>1</sub>-like receptor antagonist SCH23390 attenuated the natriuretic response by 61%, while the selective D<sub>2</sub>-like receptor antagonist sulpiride was ineffective. The urinary excretion of DA did not increase. Infusion of <i>L</i>-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 <i>L</i>-dopa-induced natriuretic response occurred without increments in glomerular filtration rate and could be blocked with the D<sub>1</sub>-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.
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

<i>Background/Aims:</i> 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. <i>Methods:</i> 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 <i>D</i>-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. <i>Results:</i> Incubation of confluent growth-arrested HPTC with 25 m<i>M</i> <i>D</i>-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 m<i>M</i> <i>D</i>-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 m<i>M</i> <i>D</i>-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 m<i>M</i> sorbitol, but not following the addition of 25 m<i>M</i> galactose to either aspect of the cells. <i>Conclusions:</i> 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 10<sup>6</sup> 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.
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.
Endotoxin-Induced Renal Failure
Authors: Heyman Samuel N. , Rosen Seymour , Darmon David , Goldfarb Marina , Bitz Helena , Shina Ahuva , Brezis Mayer 
Published: April 2003

Endotoxin-induced hypotension and altered renal microcirculation could lead to tubular injury, particularly at the physiologically hypoxic outer medulla. We explored this hypothesis in isolated perfused kidneys and in vivo in rats subjected to endotoxemia. Rat kidneys were removed 15 min after endotoxin injection in vivo (from <i>Escherichia coli</i> 0127:B8, 1 mg/kg i.p.) and perfused with oxygenated medium supplemented with 20 amino acids and endotoxin. Glomerular filtration rate and filtration fraction markedly declined (0.4 ± 0.1 ml/min and 1.1 ± 0.1, respectively) as compared with control kidneys (0.7 ± 0.1 ml/min and 1.8 ± 0.1, n = 8–12 per group; p < 0.05). Hypoxic injury to medullary thick ascending limbs in the innermost outer medulla increased (47 ± 9% of tubules vs. 16 ± 8% in controls, p < 0.05). When rats were preconditioned with an additional endotoxin injection 16 h earlier (a manipulation that markedly reduces cortical and medullary blood flow), glomerular filtration rate and filtration fraction further declined to 0.1 ± 0.0 ml/min and 0.4 ± 0.1, respectively (p < 0.01), and tubular sodium reabsorption fell to 81 ± 12 vs 98 ± 0% in controls (p < 0.05). Tubular damage, however, did not increase (20 ± 7%), probably reflecting a decline in reabsorptive workload and oxygen requirement. In rats subjected to a single or two repeated daily doses of endotoxin (1 mg/kg i.p.) plasma creatinine comparably rose 41% on the average over 24 h, creatinine clearance fell by 27% (p < 0.0001), but tubular damage was absent. By contrast, in rats preconditioned with indomethacin and the nitric oxide synthase inhibitor N<sup>G</sup>-nitro-<i>L</i>-arginine methyl ester (10 mg/kg), the addition of endotoxin markedly augmented outer medullary hypoxic tubular damage both in S<sub>3</sub> segments (27 ± 10 vs 1 ± 1%) and in medullary thick ascending limbs (38 ± 11 vs. 10 ± 5%, n = 7–8; p < 0.05). It is concluded that under special conditions, such as altered medullary oxygen balance or defective nitric oxide or prostaglandin synthesis, endotoxin may predispose to hypoxic outer medullary tubular damage.
Effects of Antenatal Thyrotropin-Releasing Hormone on Fetal Heart Rate and Breathing Movements
Authors: Peek Michael J. , Bajoria Rekha , Talbert David , Fisk Nicholas M. 
Published: April 2003

<b>Objective:</b> To determine the effect of maternally administered thyrotropin-releasing hormone (TRH) on fetal heart rate (FHR) pattern and fetal breathing movements (FBM). <b>Methods:</b> Prospective observational study of 75 pregnant women between 26 and 34 weeks’ gestation in whom pharmacological fetal lung maturation was clinically indicated. Forty-minute recordings were made of FBM or FHR patterns before and after drug administration. Twenty-five received TRH 400 µg as an intravenous bolus, 25 TRH 400 µg in 50 ml 0.9% saline as an intraveous infusion, and 25 acted as controls. Recordings were processed digitally to calculate the change in FHR (n = 45) and FBM parameters (n = 30). The main outcome measures for FHR were number of accelerations and decelerations, baseline rate, overall and short-term variation and duration of high and low variability, while for FBM they were rate, breath-to-breath interval and incidence. Results between groups were compared by analysis of variance. <b>Results:</b> There was no significant change in FHR, accelerations or variation in any of the groups. Similarly, there was no change in the incidence of FBM. TRH administered as a bolus produced a small statistically but not clinically significant increase in breathing rate (mean Δ = 35 breaths/h, p = 0.004), which was not seen in the TRH infusion and control groups. <b>Conclusions: </b>Maternally administered TRH as used to enhance fetal lung maturation has no clinically significant direct effect on FHR or FBM patterns.
Chromosomal Anomalies in Abnormal Human Pregnancies
Authors: Brajenović-Milić Bojana , Petrović Oleg , Krašević Maja , Ristić Smiljana , Kapović Miljenko 
Published: April 2003

<b>Objective:</b> The aim of this study was to describe the cytogenetic observations on abnormal human pregnancies (anembryonic pregnancy, early fetal loss, and hydatidiform moles), and to detect the most frequent or typical chromosomal aberration for anembryonic pregnancy and early fetal loss. <b>Study Design:</b> Abnormal pregnancies were divided into three clinical and morphological groups: (a) anembryonic pregnancy; (b) early fetal loss, and (c) hydatidiform mole. Of the 119 karyotyped tissue samples, 42 (35%) were from anembryonic pregnancies, 64 (54%) from early fetal losses, and 13 (11%) were from hydatidiform moles (6 complete and 7 partial moles). Long-term cultures of chorionic villi and GTG-banding techniques were used for chromosome analysis. <b>Results and Conclusion:</b> The overall frequency of chromosome anomalies among the 119 karyotyped spontaneous abortions was found to be 37.8%. Trisomy (double trisomy included) accounted for 35.6% of all aberrations, followed by polyploidy (33.3%), mosaicism (11.1%), tructural abnormalities (4.4%), and monosomy X (2.2%). Although the difference was not statistically significant, single trisomy was the predominant chromosome abnormality found in anembryonic pregnancies (64.3%) while in cases of early fetal loss, trisomy (double trisomy included) (38.9%) and triploidy (27.8%) were quite frequently present. The frequency of triploidy among all chromosomal abnormalities was 28.9%, and 53.8% of them were found in partial hydatidiform mole. The rest of them were almost exclusively found in early fetal losses. Complete hydatidiform moles (androgenetic in origin) were present in 13.3% of all aberrations, of which 83.3% had a 46,XX, and the rest of them had a 46,XY karyotype.
Assessment of the Risk of Fetal Loss after the Coelocentesis Procedure Using a Baboon Model
Authors: Santolaya-Forgas J. , Vengalil S. , Kushwaha A. , Bieniarz A. , Fortman J. 
Published: April 2003

<b>Objectives:</b> The aims of this study were to gain some insight with regard to the safety of the coelocentesis procedure and, to determine pH, pCO<sub>2</sub>, and base excess status of the extracoelomic fluid 40 days after fertilization. <b>Methods:</b> Twenty-eight timed-mated baboons from the breeding colony of the Biological Resource Laboratory at the University of Illinois at Chicago were studied. The initial 19 animals were used to determine the ultrasonographic relations between the different compartments of the gestational sac from 38 to 62 days of pregnancy. Under aseptic conditions, in 9 animals coelocenteses were then performed, under continuous transvaginal ultrasound guidance to avoid the amniotic or yolk sacs. Extracoelomic fluid (1–5 ml) was aspirated using 10-ml syringes. Only one attempt of sampling was performed in each of the 9 animals. Extracoelomic fluid pH, pCO<sub>2</sub>, and base excess were compared with maternal femoral venous blood. Pregnancies were followed by transabdominal ultrasound evaluations on day 3 after the procedure and weekly until day 140 after fertilization. <b>Results:</b> Extracoelomic fluid could be aspirated easily using a 20-gauge needle. Only one pregnancy loss was detected within 3 days after the procedure. No complications occurred in the remaining 8 pregnancies. Extracoelomic fluid pH (7.45 ± 0.01) and pCO<sub>2</sub> (39.9 ± 2.4 mm Hg) were significantly different from maternal femoral venous blood pH (7.41 ± 0.01) and pCO<sub>2</sub> (47.1 ± 1.4 mm Hg; p < 0.02), while base excess values were similar. <b>Conclusions:</b> This preliminary study performed at 40 days after fertilization in the baboon model suggests that the coelocentesis procedure is technically simple and presents a relatively low risk to mother and fetus if a 20-gauge needle is used and the amount of aspirated extracoelomic fluid is <3 cm<sup>3</sup>. At this gestational age, the extracoelomic fluid is more alkalotic than maternal femoral venous blood.