bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ouabain on Membrane Conductances and Volume in A6 Cells
Authors: Granitzer M. , Mountian I. , De Smet P. , Van Driessche W.
Published: November 2008

The present study reports the effect of a reduction in the Na+-transport rate on cell volume. A decrease in transport rate was achieved by inhibition of the basolateral Na7K+ pump with ouabain. Cultured A6 cell monolayers were short-circuited and exposed to ouabain at the basolateral surface. In one series of experiments, cells were impaled with microelectrodes to measure cell voltage, apical fractional resistance and thus derive membrane conductances. Another set, A6, served for cell height measurements. Ouabain decreased short-circuit current (Isc), which is an index of transepithelial Na+ transport: the reduction in transport rate varied from 26 to 79% within 10 min. Equivalent circuit analysis revealed a 20% decrease in apical membrane conductance (ga), whereas basolateral membrane conductance (gb) increased by 66%. A decrease in cell voltage (12 mV) together with drop in ga during ouabain may account for the reduction in Isc. The rise in gb is mainly due to a gain in Cl- conductance which increased from 114 to 613 µS/cm2, compatible with activation of Cl- channels. All of this occurs without a detectable change in cell height. We may conclude from these data that inhibition of Na+ exit by ouabain is quickly compensated by a decrease in apical Na+ entry and an increase in basolateral Cl- conductance. Constant cell volume during ouabain implies that the total cell solute is essentially unchanged.
Human Fibroblasts in Culture Exhibit a Low Sensitivity against Cyclosporin A Treatment
Authors: Dartsch Peter C. , Schmid Heide
Published: November 2008

The nephrotoxicity of cyclosporin A (CSA) after chronic treatment is well known and includes in later stages tubular atrophy associated with interstitial fibrosis. In order to examine whether interstitial ñbrosis due to CSA treatment in vivo is related to a hyperproliferative activity of fibroblasts, the effects of CSA on the growth characteristics of cultured human skin fibroblasts (HUSF) were investigated at CSA concentrations ranging from 10 ng/ ml to 50 µg/ml. We found that CSA at concentrations higher than 7.5 µg/ml inhibited cell proliferation (p < 0.05 at concentrations above 5 µg/ml; n = 3) and cloning efficiency (p < 0.05 at concentrations above 5 µg/ml; n = 3) in a dose-dependent manner and caused a promotion of cell attachment at concentrations above lOµg/ml (p < 0.05; n = 4), but did not influence cell spreading. At lower concentrations CSA-treated HUSF did not differ in their growth characteristics from the corresponding controls. A 50% inhibition of proliferation was calculated by extrapolation for a CSA concentration of 70 µg/ml for HUSF. The inhibition of HUSF proliferation was reversible even at the highest CSA concentration of 50 µg/ml. Under the same experimental conditions, a 50% inhibition of proliferation was observed for Madin-Darby canine kidney (MDCK) cells to be 5.5 µg/ml, e.g. at a 15-fold lower CSA concentration. Moreover, CSA caused a dose-dependent and reversible cell elongation of HUSF and a significant increase in the average cell diameter from 19.2 ± 0.3µm (control; mean ± SEM, n = 4) to 22.2 ± 0.2 µm for 50 µg/ml CSA (mean ± SEM, n = 4) and in median cell volume from 4,21·± 160 fl (control; mean ± SEM, n = 4) to 7,020 ± 190 fl for 50 µg/ ml CSA (mean ± SEM; n = 4). These alterations described above were not correlated with a cytotoxic effect as checked by a fluorescent staining for cell vitality. Alterations in the organization of cytoskeletal components such as stress fibers, intermediate-sized filaments and microtubules directly due to CSA treatment were not observed. In contrast, the amount of fibronectin present on the cell surface was considerably increased by CSA. Although HUSF in culture do not respond to CSA treatment by an increased proliferative activity, they are much less affected by CSA than other cell types (i.e MDCK cells). Thus, the increase in cell diameter and cell volume, respectively, and the increased amounts of surface fibronectin might explain the development of interstitial fibrosis in the kidney of humans and animals after chronic CSA treatment.
Evidence for an Inhibitory Effect of Kallikrein on Collecting Duct Bicarbonate Secretion in Rats and Rabbits
Authors: Marin-Grez Marcos , Vallés Patricia
Published: November 2008

The luminal membrane of collecting duct cells, especially the intercalated cells, is normally exposed to active kallikrein. This is the consequence of the specific localization of this renal enzyme in the connecting tubule cells and its principal route of secretion being into the tubular lumen. It is conceivable that kallikrein acts downstream on a transporter involved in distal bicarbonate handling. To investigate this possibility, we estimated bicarbonate concentration and measured kallikrein amidolytic activity in urine fractions collected after a classical stop-flow experiment in rabbits. A highly significant inverse correlation was found between these parameters (r = -0.94, p < 0.001) in the peak kallikrein fractions. Neither sodium nor potassium concentration were correlated to kallikrein. This suggests that the physiological role of renal kallikrein may be to regulate extracellular fluid pH by inhibiting collecting duct bicarbonate secretion. To test the hypothesis that tubular fluid kallikrein activity and bicarbonate secretion are causally related, we developed a novel in vivo stop-flow injection model (‘orthograde stop-flow’). A hog-kallikrein containing solution (0.5 µg/ml) was injected through the abdominal aorta into the renal tubular system of one kidney of barbiturate-anesthetized rats, while the renal blood supply was interrupted. The ureter was then occluded and renal blood perfusion reinitiated. After a 2-min contact time five 125-µl urine fractions were collected. Bicarbonate secretion was clearly detected in the second and third fractions (i.e. those coming from the collecting ducts) of the control animals, which had received only the vehicle. There was no bicarbonate secretion peak in the corresponding urine fractions collected from kallikrein-injected animals. We conclude that intraluminal kallikrein inhibits collecting duct bicarbonate secretion, probably by inhibiting the chloride/bicarbonate exchanger of β-intercalated cells.
Laminin and Fibronectin Content of Mouse Glomerular and Tubular Basement Membrane
Authors: Brees Douglas K. , Ogle Roy C. , Williams, Jr. James C.
Published: November 2008

Because the glomerular basement membrane (GBM) is subject to damage in a multitude of renal diseases, a model of basement membrane permeability properties would be useful for learning more about this important barrier. Isolated, perfused tubular basement membrane (TBM) allows measurement of permeability, but it is not known whether TBM is similar enough to GBM for data to be extrapolated from this model to the glomerulus. As a first approach to assessing differences between GBM and TBM, we looked at composition. Renal glomeruli and tubules were isolated from Swiss-Webster mice by sucrose-gradient centrifugation. GBM and TBM were isolated by sonication in 1% deoxycholate and then subjected to a sequential extraction procedure. Analysis of the solubilized basement membranes by electrophoresis revealed a complex mixture of proteins. Immunoblot analysis demonstrated that, among the proteins, laminin and fibronectin were found exclusively in the guanidine and guanidine/dithiotreitol extracts. The total amount of laminin extracted in GBM, 1.8+0.001 µg/mg dry weight (n = 2 groups animals, by inhibitory ELΙSA), was significantly less than in TBM, 3.4+0.1 µg/mg dry weight (n = 2); however, the total amount of fibronectin extracted did not differ between GBM and TBM, 8.2 ± 0.8 and 7.7 ± 1.0 µg/mg dry weight (n = 2) respectively. Examination of deoxycholate supernatants was carried out to see if components of GBM or TBM were solubilized during isolation of basement membranes. Immunoblot analysis revealed loss of some laminin and fibronectin occurred during the detergent isolation of GBM and TBM. We conclude that GBM and TBM are qualitatively similar in that they have the same protein components, but differ significantly in content of laminin and probably other macromolecular components.
Tubuloglomerular Feedback in Rats with Chronic Partial Bilateral Ureteral Obstruction
Authors: Morsing Peter , Stenberg Arne , Wåhlin Nils , Persson A. Erik G.
Published: November 2008

Rats with chronic partial unilateral ureteral obstruction (UUO) have a paradoxical resetting of the tubuloglomerular feedback (TGF) mechanism. During extracellular fluid volume expansion (VE) in control animals, a decrease in TGF sensitivity is normally noted. In rats with partial UUO, however, TGF sensitivity in the obstructed kidney was increased, associated with a relative reduction in single nephron glomerular filtration rate. In the present study, we examined the tubular and interstitial pressures, whole kidney function and the TGF system in rats with chronic partial bilateral ureteral obstruction. The rats were divided into preferentially ipsilaterally and preferentially contralaterally obstructed, as judged by pelvic volume. Measurements were performed both during hydropenia and during VE. During hydropenia TGF characteristics were the same in the 2 groups. During VE, however, TGF sensitivity was unchanged in the most obstructed kidneys (ipsilateral), while if the obstruction was preferentially contralateral, TGF sensitivity decreased. This opposite change in TGF sensitivity resulted in higher electrolyte and water excretion from the least obstructed kidney. The change in TGF sensitivity was not correlated to renal interstitial pressure. In conclusion: rats with moderate chronic partial bilateral ureteral obstruction have an almost preserved function with regard to renal hemodynamics and excretion during hydropenia. During volume expansion, however, different responses were found in the least and most obstructed kindeys, with a decreased sensitivity of TGF in the least obstructed kidney, while TGF sensitivity was unchanged in the most obstructed kidney.
Prostaglandin-lndependent Decrease of Sheep Ureter Contractility Induced by Bradykinin
Authors: Kaygisiz Ziya , Dönmez Turgut , Uyar Ruhi , Ertürk Mahmut , Soydan Mehmet
Published: November 2008

The machanisms that mediate the actions of bradykinin on ureteral motility are poorly defined and mediation via prostaglandins has not been examined. Therefore, the effects of bradykinin on contractility and the possible mediator role of prostaglandins have been investigated in sheep ureter. At the concentrations of 10-8, 10-7 and 10-6M, bradykinin elicited marked reductions in contractile force. When ureteral strips were treated separately with 10-6M indomethacín, 2x10-6M sodium salicylate and 10-5 M aspirin, each drug produced a significant decrease in contractile force. In strips in which prostaglandin synthesis was inhibited by the above concentrations of indomethacin, sodium salicylate and aspirin, 10-7M bradykinin significantly decreased the contractility. From these data, we concluded that in ureter bradykinin decreases contractility via a mechanism not involving prostaglandin generation.
Altered Extracellular Matrix Component Gene Expression in Murine Polycystic Kidney
Authors: Ebihara Isao , Nakamura Tsukasa , Takahashi Toshimasa , Yamamoto Masatoshi , Tomino Yasuhiko , Nagao Shizuko , Takahashi Hisahide , Koide Hikaru
Published: November 2008

The DBA/2FG-pcy mouse has a form of slowly progressive kidney disease that appears similar in many respects to that seen in the autosomal dominant form of human polycystic kidney disease. This study was designed to assess how the expression of extracellular matrix component genes is regulated in a model of murine polycystic kidney disease and control DBA/2 mice at 8, 16, and 30 weeks of age. The mRNA levels encoding for collagen IV, the B1 and B2 chains of laminin, heparan sulfate proteoglycan, fíbronectin, and collagens I and III increased with the progression of cystic lesions in the kidney of DBA/2FG-pcy mice. At 30 weeks of age, mRNA levels for collagen IV, laminin B1 and B2, heparan sulfate proteoglycan, fíbronectin, and collagens I and III were increased 8.1-fold, 7.0-fold, 7.0-fold, 9.8-fold, 7.0-fold, 5.5-fold, and 5.4-fold, respectively, compared to those of control DBA/2 mice. An immunofluorescence study revealed the irregular staining for collagen IV, laminin, heparan sulfate proteoglycan, and collagens I and III around the cysts. These data suggest that changes in the expression of basement membrane components and interstitial collagens are associated with the development of polycystic kidney disease.
L-Arginine Reduces Kidney Lipid Peroxidation, Glycoxidation and Collagen Accumulation in the Aging NMRI Mouse
Authors: Lubec B. , Golej J. , Marx M. , Weninger M. , Hoeger H.
Published: November 2008

Collagen accumulation in organs is a main feature of the physiological aging process. There are two main theories for the responsible mechanisms, the free oxygen radical and the glycoxidation theory. Both lead to carbonyle-induced protein modification, increased collagen cross-linking and subsequently to the collagen accumulation. In previous studies we provided evidence for the blocking of reactive carbonyles by L-arginine in the diabetic state and present here data for this effect in the aging NMRI mouse. NMRI mice were fed L-arginine in tap water for a period of 6 months and compared to an untreated control group. Kidney collagen content of the treated group was significantly reduced (treated: 8.83+0.72 mg collagen/100 mg kidney weight; untreated: 11.95 ± 0.98mg collagen (100 mg kidney weight; p < 0.05). Using a colorimetric assay for lipid peroxidation products we found significantly reduced lipid peroxidation-derived aldehydes in the treated group (treated: 0.25 ± 0.03 extinction; untreated: 0.36 ± 0.04 extinction; p < 0.05). The parameter for glycoxidation, N-Ε-carboxymethyllysine (CML) was significantly lower in the experimental group as well (treated: 2.3 ± 0.5 nM CML/µM hydroxyproline; untreated: 4.3 ± 0.52 nM CML/µ/Vf hydroxyproline; p < 0.05). No differences were observed for the biomarker of hydroxyradical attack, o-tyrosine. L-Arginine could have reduced collagen accumulation by blocking collagen glyc(oxidation) which is known to lead to increased collagen cross-linking, solubility and degradation as a strong correlation between both CML and collagen content (r = 0.654, p < 0.05) as well as between lipid peroxidation products and collagen content (r2 = 0.539, p < 0.05) was observed.
Purification and Immuno- histochemical Localization of a 17-kD Porcine Renal Puromycin Aminonucleoside Binding Protein
Authors: Wakui Hideki , Komatsuda Atsushi , Kodama Takahito , Mamiya Shigeo , Miura Akira B.
Published: November 2008

We have purified a 17-kD puromycin aminonucleoside (PAN) binding protein from porcine kidney and identified it as the reported 17-kD protein kinase C inhibitor on the basis of its partial amino acid sequence. Of 54 determined amino acid sequences of the 17-kD porcine renal protein, 51 residues were identical to those of the 17-kD bovine brain protein kinase C inhibitor. However, our purified protein did not carry the inhibitory activity on protein kinase C. Immunohistochemical studies showed a unique intrarenal distribution of the 17-kD PAN-binding protein at the apical side of epithelial cells of Henle’s loops in the inner medulla and of distal convoluted tubules. Immunoblot analysis revealed that the 17-kD PAN-binding protein was extractable by an isotonic buffer without sodium deoxycholate extraction. These results suggest that this protein binds loosely to the apical membranes of epithelial cells of Henle’s loops and distal tubules and has specific functions related to tubular functions of these nephron segments at the apical side. Whether this protein is a real inhibitor of protein kinase C or not remains to be investigated.
Cross-Talk between the Na+-K+-ATPase and the H+-ATPase in Proximal Tubules in Suspension
Authors: Fleser A. , Marshansky V. , Duplain M. , Noël J. , Hoang A. , Tejedor A. , Vinay P.
Published: November 2008

The cellular energy required for the activity of the Na+-K+-ATPase and of the H+-ATPase was estimated in intact proximal tubules in suspension. Both the fall in oxygen consumption (directly measured) and NADH oxidation (as estimated from exogenous substrate metabolism) were measured before and following application of ouabain (1 mM) to inhibit the sodium pump, following bafilomycin (0.1 mM) to inhibit the proton pump or following a combination of these inhibitors. The data demonstrate that the sodium pump utilizes 43% and the proton pump 19% of the phosphorylating NADH turnover of canine proximal tubules studied in vitro. However, a significant and stoichiometric stimulation of one pump was observed upon inhibition of the other. The NADH turnover related to the sodium pump increased from 308 to 402 (Δ = 94) µmol · g-1 wet weight · h-1 following bafilomycin application and that of the proton pump from 136 to 230 (Δ = 94) following ouabain application. This stimulation was largely abolished by inhibition of the Na+/H+ exchange occurring in either direction by amiloride or methylisobutylamiloride. It is concluded that a cross-talk occurs between the basolateral sodium pumps and the proton pumps located on the brush border membrane and/or on endosomes in proximal tubules. This cross-talk appears to be mediated by Na+/H+ exchange suggesting that both the proton pump and the Na+/H+ exchanger may contribute in a cooperative fashion to the proximal secretion ofprotons.
Properties and Regulation of pH-Dependent Cation Channels in the Apical Membrane of Cultured Proximal Tubule Cells
Authors: Löffler Karin , Schwegler Johann S. , Silbernagl Stefan
Published: November 2008

The established opossum kidney (OK) cell line serves as a model system for ion and substrate transport in the renal proximal tubule. Previous experiments on OK cells revealed a channel-mediated Na+ conductance which is regulated by intracellular pH (pHi). In this study we report on patch clamp experiments determining the properties and pHi dependence of a cation channel located in the apical membrane. This channel is selective for sodium over chloride but discriminates poorly between the monovalent cations Na+, K+, Li+ and Cs+. Its open probability (Po) rises at depolarising membrane potentials. Under normal conditions the channel is inactive in the cell-attached patch mode and is activated upon excision. However, after excision the channel usually runs down within 30-90 s which cannot be overcome by either altering the Ca2+-concentration (10-3mol/l, 10-6mol/l, Ca2+-free) or adding 1 mmol/l Mg-ATP to the bath solution. In the cell-attached patch mode the channel could be activated by decreasing pHi from pH 7.4 to pH 6.5, by either the ammonium prepulse technique or the nigericin K+ method, in more than 50% of the experiments performed. In the renal proximal tubule such a non-selective cation channel would constitute a functional Na+ channel and might therefore support Na+ reabsorption especially during the intracellular acidification due to hormonal inhibition of the Na+/H+ exchanger.
Effects of Glyburide on Renal Tubule Transport and Potassium-Channel Activity
Authors: Wang Tong , Wang Wen-Hui , Klein-Robbenhaar Geertruida , Giebisch Gerhard
Published: November 2008

Renal clearance, microperfusion and patch-clamp techniques were used to investigate the effects of the K-channel blocker glyburide on electrolyte excretion, the transport properties of the thick ascending limb (TAL) of Henle and K-channel activity in the apical membrane of the TAL and of the cortical collecting tubule. Our data suggest that the K-channel blocker glyburide can inhibit transport of Na and K in the TAL by blocking K recycling across the apical membrane. Additionally, inhibition of K secretion in the collecting ducts occurs by decreasing the activity of apical K channels and prevents kaliuresis.
Effects of Enalapril Treatment on Gene Expression of Smooth Muscle Myosin Heavy Chain Isoforms in Glomeruli of Diabetic Rats
Authors: Nakamura Tsukasa , Ebihara Isao , Fukui Mitsumine , Makita Yuichiro , Tomino Yasuhiko , Kimura Kenjiro , Nagai Ryozo , Yazaki Yoshio , Koide Hikaru
Published: November 2008

We have previously shown that smooth muscle contains three types of myosin heavy chains: SM1, SM2, and SMemb. The present study was designed to assess how glomerular expression of mRNA for these isoforms is regulated and whether their expression is affected by enalapril treatment in diabetic rats. Animals were divided into 4 groups: (1) untreated diabetic rats; (2) enalapril-treated diabetic rats; (3) untreated control rats, and (4) enalapril-treated control rats. Enalapril treatment was continued for 24 weeks. The glomerular mRNA levels for SM1 and SM2 showed little change in all groups throughout the experimental period. In contrast, SMemb mRNA in group 1 increased significantly with age compared to levels found in untreated controls (4.6-fold higher at 4 weeks, p < 0.01; 6.8-fold higher at 12 weeks, p < 0.01, and 10.6-fold higher at 24 weeks, p < 0.001). Enalapril reduced both creatinine clearance (p < 0.01) and urinary protein excretion (p < 0.01) in diabetic rats. Moreover, enalapril significantly attenuated the increase in the glomerular SMemb mRNA level in diabetic rats (the difference between treated and untreated rats was significant at p < 0.01 from week 4 to 24). However, enalapril had no effect on SMemb mRNA levels in controls. These data suggest that SMemb is a molecular marker for phenotypic alteration and that the beneficial effect of enalapril on proteinuria and renal function may be, at least in part, associated with reducing SMemb mRNA expression in diabetic glomeruli.
Mercapturic Acid Formation in Cultured Opossum Kidney Cells
Authors: Golenhofen Nikola , Heuner Almut , Schwegler Johann S. , Silbernagl Stefan
Published: November 2008

We investigated the last step of mercapturic acid formation, the N-acetylation of cysteine S-conjugates, in the established opossum kidney (OK) cell line which exhibits characteristics of the proximal tubule. S-Benzyl-L-cysteine was used as a model substance for such a cysteine S-conjugate. We succeeded in showing that OK cells absorb S-benzyl-L-cysteine via an active transport system which is inhibitable by phenylalanine. This transport follows Michaelis-Menten kinetics and the two characterizing parameters were determined: the Michaelis-Menten constant Km = 1.8mmol/l, and the maximum of the difference between the intracellular and the extracellular concentration of S-benzyl-L-cysteine △cmax = 19.4 mmol/l. S-Benzyl-L-cysteine is converted to N-acetyl-S-benzyl-L-cysteine at a constant rate, which is independent of the extracellular S-benzyl-L-cysteine concentration. Under the tested experimental conditions this is probably due to saturation of the microsomal N-acetyltransferase catalyzing this reaction. In conclusion, we have shown that OK cells are a suitable model for studying mercapturate formation. They take up S-benzyl-L-cysteine mainly via the same carrier as phenylalanine, which is known to be transported in the rat by the high-capacity, low-affinity neutral amino acid carrier, and convert it to N-acetyl-L-benzyl-S-cysteine.
Nitric Oxide Does Not Contribute to Sodium Retention and Peripheral Vasodilation Induced by Partial Portal Vein Ligation in Rats
Authors: Murakami Shigeto , Bernardo José F. , Jacob Timothy D. , Branch Robert A. , Sabra Ramzi
Published: November 2008

The role of nitric oxide (NO) synthesis in the peripheral vasodilation and sodium retention that occurs after partial portal vein ligation (PVL) was investigated. Hemodynamic studies in PVL rats with sodium retention and in sham-operated controls were conducted on the day when PVL rats developed transient and maximal sodium retention. Measurements were obtained before and during two consecutive periods after NO synthesis inhibition with NG-monomethyl-L-arginine (L-NMMA). Under baseline conditions, PVL rats with sodium retention were hypotensive, with equivalent decreases in total peripheral resistance and glomerular filtration rate in comparison to the control group. After L-NMMA, peripheral resistance and arterial pressure increased by similar extent in both groups. As compared with controls, PVL rats with sodium retention remained hypotensive and vasodilated. Furthermore, L-NMMA-induced natriuresis was attenuated in the PVL group. Additionally, serum and urinary levels of nitrate and nitrite did not vary before surgery and at the time of sodium retention. These results suggest that in PVL rats (1) vasodilation is not NO mediated; (2) vasodilation is not a sufficient explanation for sodium retention, and (3) a sodium-retaining factor acting on the renal tubules is responsible for sodium retention.
Micropuncture Study of the Effect of Furosemide on Proximal and Distal Tubules of the Rat Nephron
Authors: Roman G. , Favret G. , Bartoli E.
Published: November 2008

The tubular effects of furosemide were studied by micropuncture and clearance techniques on 20 rats. Collections of tubular fluid (TF) from early distal (ED) and late proximal (LP) segments of the same nephrons and of different nephrons were performed during baseline conditions. Re-collections were taken from the same sites and new collections from different nephrons after 10 mg/kg furosemide. The glomerular filtration rate (GFR) was 1,309 ± 212µl/min during baseline, and 1,348 ± 199 µl/min after furosemide (p > 0.89); while the urine flow rate rose from 36 ± 8 to 167 ± 30µl/min (p < 0.001). The nephron filtration rate (NFR) was not different in 46 paired distal (33.3 ± 2.6 nl/min) versus proximal samples (34.2 ± 2.9 nl/min, p > 0.72), neither was it different during baseline (37.2 ± 1.4, n = 120) as compared to furosemide (37.2 ± 2.7, n = 91, p > 0.99). The percent reabsorption (PR) at the ED sampling site was 87 ± 4% during baseline, and 89 ± 3% in 13 paired samples during furosemide (p > 0.47). PR at the LP sampling sites was 83 ± 2% during baseline, and 80 ± 2% in 26 paired samples during furosemide (p > 0.63). In 31 paired ED-LP collections, PR was 82+4 (ED) versus 72 ± 4% (LP) during baseline, and 87 ± 3 versus 74 ± 6%, respectively, during furosemide. The respective collection rates were 4.6 ± 1.0 versus 9.5 ± 1.3 nl/min during baseline (p < 0.0001), 5.8 ± 2.3 versus 8.7 ± 3.0 nl/min during furosemide. The LP-ED differences obtained during baseline were not different from those measured during furosemide for the collection rate, PR and NFRs. The absolute LP resorption rate was not significantly different during baseline as compared to furosemide. Thus, furosemide did not affect the difference between ED and LP collection sites in collection rate, absolute and fractional reabsorption, in the absence of changes in GFR and NFR. These data indicate that furosemide acts solely along Henle’s loop, where it blocks Na+ transport. The urine flow rate rises during furosemide because water abstraction along the distal tubule is reduced by the isotonicity of ED TF, and along the collecting ducts by the isotonicity of the medullary and papillary interstitium caused by the diuretic. We conclude that under the conditions of the present study, furosemide has no proximal effect.
Interaction between Adrenergic Agonists and Forskolin on Adenylate Cyclase Activity in the Rabbit Proximal Tubule
Authors: Beck J.S. , Burgess W.J. , Balment R.J.
Published: November 2008

Using a micro-radioimmunoassay, cAMP was measured in single, isolated S2 proximal straight tubules dissected from rabbit kidneys to investigate the effects of adrenergic agonists on adenylate cyclase activity. The baseline activity of adenylate cyclase was low and unaffected by either the α2 agonist clonidine, the β agonist isoprenaline (in the absence or presence of 1 µM forskolin) or 1 µM forskolin. Adenylate cyclase activity was markedly stimulated by 20 µM forskolin, an effect which was inhibited by 1 µM clonidine. The inhibition by clonidine was not apparent in the presence of the α2 antagonist yohimbine. These results confirm the inability of isoprenaline to stimulate adenylate cyclase in the rabbit proximal tubule and demonstrate the coupling of α2 receptors, in an inhibitory fashion, to adenylate cyclase. The inhibitory action of the α2-receptor agonist was independent of other hormone activity in the renal proximal tubule.
The Angiotensin l-Converting Enzyme Inhibitor, Cilazapril Inhibits the Platelet-Derived Growth Factor B Chain Expression in Glomeruli of Spontaneously Hypertensive Rats
Authors: Yamauchi Takayoshi , Ogura Toshio , Oishi Tetsuya , Omiya Teruaki , Ota Zensuke
Published: November 2008

To clarify whether in vivo expression of growth factors in the glomerulus is induced in a hypertensive animal model, we investigated the expression of platelet-derived growth factor (PDGF) B chain, transforming growth factor beta (TGF-β), and angiotensin II (Ang II) type 1 receptors in glomeruli of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. We also investigated the effects of treatment with cilazapril, an angiotensin I-converting enzyme inhibitor, on this expression. First, the expression of PDGF B chain, TGF-β, and Ang II receptors from the glomerulus were investigated using the reverse-transcriptase polymerase chain reaction in SHR and WKY rats. Although there was no significant difference in PDGF B chain, TGF-β, and Ang II receptors from the glomerulus were investigated using the reverse-transcriptase polymerase chain reaction in SHR and WKY rats. Although there was no significant difference in PDGF B chain, TGF-β or Ang 11 receptor expression between SHR and WKY rats at the age of 7 weeks, the PDGF B chain expression of 16-week-oId SHR was significantly higher (4.4-fold) than that of age-matched WKY rats. Next, we administered oral cilazapril at a dose of 10 mg/kg to 13-week-old SHR daily for 3 weeks. The systolic blood pressure in SHR treated with cilazapril was significantly lower than that in control SHR. After administration of cilazapril for 3 weeks, we examined the in vivo expression of growth factors and Ang II receptors in the glomerulus. The PDGF B chain expression was suppressed by treatment with cilazapril (2.5-fold) as compared with non-treated SHR. No alteration in TGF-β or Ang II receptor expression was detected. We did not find any histological changes in the kidneys of SHR, WKY rats or cilazapril-treated SHR, and cilazapril treatment did not suppress the glomerular size. These findings indicate that the expression of PDGF B chain in the glomerulus preceded the appearance of histological changes in SHR and that the administration of cilazapril inhibited the expression of PDGF B chain without affecting the glomerular size. This suggests that angiotensin I-converting enzyme inhibitors directly suppress the Ang II-induced PDGF B chain promotion in the glomerulus of SHR at the established hypertensive stage.
Inhibition of cGMP-Phosphodiesterase Restores the Glomerular Effects of Atrial Natriuretic Factor in Low Sodium Diet Rats
Authors: Kalinowski Leszek , Szczepanska-Konkel Miroslawa , Pawelczyk Tadeusz , Bizon Dorota , Angielski Stefan
Published: November 2008

It was shown that atrial natriuretic factor (ANF)-induced increase in glomerular filtration rate (GFR) is blunted in low sodium diet. We investigated whether saralasin, as an angiotensin II receptor antagonist, or verapamil, as a calcium entry blocker, or theophylline and zaprinast, as inhibitors of cGMP-phosphodiesterase activity, could restore the effect of ANF on GFR increase in low sodium diet rats. ANF alone (5 µg/kg bolus then 0.5 µg/min/ kg BW maintenance) increased diuresis and natriuresis to the same extend in low and normal sodium diet rats but had no GFR-increasing effect in low sodium diet rats. Infusion of ANF in the presence of verapamil, saralasin, theophylline or zaprinast induced a significant increase in GFR and filtration fraction (FF). Administration of verapamil or saralasin alone did not alter GFR and FF whereas theophylline or zaprinast alone resulted in moderate but significant increases in both parameters. The increase of nephrogenous cGMP excretion in response to ANF infusion in low sodium diet rats was markedly lower as compared to normal sodium diet rats (243.4 ± 43.3 vs. 444.0 ± 35.6pmol/min, respectively, p < 0.01). Administration of a selective inhibitor of cGMP-phosphodiesterase activity (zaprinast) abolished the differences in ANF-stimulated nephrogenous cGMP excretion in low and normal sodium diet rats. Basal and peak ANF (0.5 µM)-stimulated cGMP formation by isolated glomeruli was significantly lower in low than normal sodium diet rats (1.4+0.1 vs. 2.9 ± 0.2 and 7.1+0.5 vs. 12.5+1.1 pmol/mg protein, for basal and ANF-stimulated cGMP formation, respectively; both p < 0.05). Zaprinast both alone and in combination with ANF, potentiated cGMP formation by glomeruli isolated from both groups of rats. In the presence of zaprinast, there were no differences in both basal and peak ANF-stimulated cGMP formation by glomeruli isolated from low and normal sodium diet rats. cGMP-phosphodiesterase activity was the same in the medulla of both groups of rats but markedly higher in the renal cortex of low sodium diet rats as compared to normal sodium diet rats (82.6 ± 6.0 vs. 59.8 ± 4.3, respectively; p < 0.05). These data suggest that the lack of GFR-increasing response to ANF in low sodium diet rats is primarily due to the increase of cGMP hydrolysis in glomeruli.
Nifedipine Reduces Postexercise Proteinuria in Young Volunteers
Authors: Cosenzi Alessandro , Carraro Michele , Sacerdote Ariela , Bocin Elena , Molino Rossella , Benazzi Teresa , Artero Mary L. , Faccini Luigi , Bellini Giuseppe
Published: November 2008

Previous studies have demonstrated that it is possible to prevent postexercise proteinuria with angiotensin-converting enzyme inhibitors. To determine whether calcium antagonists have the same effect, 40 young healthy volunteers underwent maximal aerobic exercise with and without nifedipine 10 mg per os 1 h before the first or second trial. Urinary excretion of albumin (UAE), transferrin (UTE) and α1-microglobulin (UME) were examined before and after each trial. UAE, UTE and UME were significantly increased after exercise. Nifedipine significantly decreased UAE (p = 0.001) and UTE (p = 0.02) after exercise, and slightly decreased the maximal work load and the basal excretion of albumin. UME was unchanged. Therefore, the results of this study demonstrate that nifedipine administration before exercise significantly reduces postexercise proteinuria.
Effect of Volume Expansion on the Natriuretic Response to Ouabain Infusion
Authors: Yates N.A. , McDougall J.G.
Published: November 2008

Evidence exists that an endogenous substance which inhibits (Na+, K+)-ATPase, in a similar manner to the cardiac glycosides, may have important cardiovascular and renal effects. Whilst ouabain or a closely related isomer has been reported to be present in mammalian plasma, renal effects of ouabain occur only at high concentrations. The effect of expansion of blood volume on the renal response to ouabain infusion was examined in conscious sheep. Five sheep with catheters chronically implanted into the renal artery received four treatment combinations in random order: (I) vehicle (0.15 mol l-1 NaCl) infusion; (II) 500 µg ouabain infused into the renal artery over 60 min; (III) 500 ml 6% dextran 70 in 0.9% saline infused intravenously, and (IV) the dextran and ouabain treatments together. Treatment with either ouabain or plasma volume expansion produced modest increases in sodium excretion and urine flow. Treatment with ouabain when combined with plasma volume expansion increased sodium excretion from 82 ± 30 to 880 ± 203 µmol min-1 and urine flow from 1.9 ± 1.1 to 7.5+1.6 ml min-1. This combination of treatments results in a synergistic rather than additive response. This study indicates that under some circumstances the response of the kidney to inhibition of (Na+, K+)-ATPase can be enhanced and, if inhibition can be demonstrated to occur at physiologically relevant concentrations of endogenous digitalislike factor, would support a possible physiological role for endogenous digitalislike factor in the regulation of sodium homeostasis.
The Effects of Desvenlafaxine and Paroxetine on the Pharmacokinetics of the Cytochrome P450 2D6 Substrate Desipramine in Healthy Adults
Authors: Nichols Alice I. , RN Penny Fatato , Shenouda Magdy , Paul Jeffrey , Isler Jennifer A. , Pedersen Ronald D. , Jiang Qin , Ahmed Saeeduddin , Patroneva Albena
Published: November 2008

The potential for cytochrome P450 (CYP) 2D6 substrates to interact with desvenlafaxine (administered as desvenlafaxine succinate) and paroxetine was evaluated. In an open‐label, crossover study, 20 healthy volunteers (aged 21–50) were randomized to 2 series of 9 days each of desvenlafaxine (100 mg/d) or paroxetine (20 mg/d), separated by a 5‐day washout. The CYP2D6 substrate desipramine (50 mg) was administered alone on day 1 and coadministered on day 6 of dosing with either desvenlafaxine or paroxetine. CYP2D6 genotype was determined at baseline. Based on least squares geometric mean ratios between reference (desipramine alone) and test treatments, desvenlafaxine produced minor increases in desipramine area under the plasma concentration versus time curve (AUC; 36%) and peak plasma concentration (Cmax; 30%) (vs paroxetine: 419%, 90%, respectively; bothP< .001). Desvenlafaxine produced little change in 2‐hydroxydesipramine AUC (16% increase) and Cmax(0%) versus paroxetine (18% and 82% decreases, respectively;P= .008,P< .001, respectively), indicating that desvenlafaxine, especially at the recommended therapeutic dose of 50 mg/d for major depressive disorder in the United States, has little potential to interact with CYP2D6 substrates.
The Myth of the Coming Charitable Estate Windfall
Authors: James Russell N.
Published: November 2008

Media accounts, fund-raising periodicals, and some academic research have pointed to a coming windfall of charitable estate transfers driven by the graying of the population. Nonprofit managers and public agencies working with nonprofits or their beneficiaries may incorporate these expectations into their long-range planning. This article presents the first comparison of estate gifts (for both taxable and nontaxable estates) with the previous annual giving and volunteering of the deceased. An analysis of approximately 6,000 deceased panel members from the 1995—2006 Health and Retirement Study suggests that estate gifts are largely offset by the loss of current giving and volunteering previously provided by the deceased donors. Consequently, nonprofit managers who plan based on anticipated future charitable giving estate windfalls may make erroneous choices.
Experimental Study on Retrofitting of Stressed RC Beams using GFRP Jackets
Authors: Bansal Prem Pal , Kumar Maneek , Kaushik S.K.
Published: November 2008

In the present study, the effect of fiber orientation and stress level on the strength of stressed beams retrofitted with GFRP jackets is studied. The beams were initially stressed up to 60, 75, and 90% of their safe load and then retrofitted with GFRP jackets with fibers in different orientations. The results show that the beams retrofitted using GFRP jackets with fibers at 45° to the longitudinal axis yield a higher increase in the maximum load carrying capacity, i.e., approximately 30—35% in case of under-reinforced sections and 13—17% in case of balanced sections as compared to beams retrofitted using fibers at 0° to the longitudinal axis. A considerable increase in the ductility ratio is also observed for both the fiber orientations.
Communicable disease policy development in response to changing European political frontiers in Finland, Norway and Sweden
Authors: Bernitz Brita Kaltenbrunner
Published: November 2008

Aims: The European Union (EU) enlargement of 2004 brings both opportunities and challenges for public health. It is believed that further integration will bring direct health benefits, mainly through improved socioeconomic conditions, but there are also risks associated with the EU expansion, in particular cross-border health risks, such as the impact of the internal EU market policy of free movement and migration on communicable disease patterns. Against this background, this article examines communicable disease policy development in Finland, Norway and Sweden in response to changing European political frontiers, in particular the EU accession of the Baltic States. The emphasis is on HIV/AIDS and tuberculosis. Methods: The study is based on a qualitative and quantitative approach, using two complementary methods: documentary analysis and stakeholder analysis. Results: The article identifies a distinct pattern in communicable disease policy development between 1990 and 2005. The turn of the new millennium saw a sharp increase in national attention and the priority assigned to communicable diseases in Finland, Norway and Sweden. The article argues that this development is likely to be related to the rising national, regional and European awareness of the public health challenges associated with communicable diseases in today's borderless Europe. It also shows that the Baltic health situation is a particular concern for Finland. Conclusions: Although there is increasing national and regional activity within the communicable disease area, there is a need for a more effective European approach to tackle the future communicable disease challenges that may follow in an increasingly interdependent and integrated Europe.
Encouraging the installation of rollover protective structures in New York State: the design of a social marketing intervention
Authors: Sorensen Julie A. , May John , Ostby-Malling Ronne , Lehmen Tom , Strand John , Stenlund Hans , Einehall Lars W. , Emmelin Maria
Published: November 2008

Aims: Increasing the percentage of rollover protective structure (ROPS) equipped tractors has been the focus of many agricultural safety campaigns. Traditionally efforts have attempted to persuade farmers through education or community awareness interventions. These efforts have lead to marginal change. In response, a social marketing approach was tested as a means for increasing interest in ROPS retrofitting in New York. Methods: An initial phone survey was conducted with a random sample of New York farmers to identify a potential target population. Following target selection, in-depth interviews were conducted to isolate barriers and motivators to retrofitting. This information was used to develop message prototypes which were tested in small focus group discussions. Selected and revised messages, as well as various other incentives developed in response to feedback from interviews, were then tested in a prospective, quasi-randomized controlled trial. Results: Small crop and livestock farms were selected as the intervention target since they represent 86% of New York farms with none or only one ROPS protected tractor. Barriers to retrofitting which were identified in interviews were: 1) constant exposures normalize risk, 2) risk is modeled by significant others and 3) safety in general and retrofitting in particular requires too much time and money. The piloting of ROPS incentives led to a marked increase in ROPS sales in New York. Conclusions: Social Marketing provides a promising framework for the design of agricultural injury prevention programs. The potential implications for other health initiatives seeking to promote behaviour change are also discussed.
Managerial leadership is associated with self-reported sickness absence and sickness presenteeism among Swedish men and women
Authors: Nyberg Anna , Westerlund Hugo , Magnusson Hanson Linda L. , Theorell Töres
Published: November 2008

Aims: The objective of this study was to investigate the relationship between managerial leadership and self-reported sickness absence/presenteeism among Swedish men and women. Methods: Five thousand one hundred and forty-one Swedish employees, 56% of the participants in a nationally representative sample of the Swedish working population, were included in this cross-sectional questionnaire study. The leadership dimensions measured were five subscales of a standardized leadership questionnaire (Global Leadership and Organizational Behaviour Effectiveness Programme): Integrity, Team integration, Inspirational leadership, Autocratic leadership, and Self-centred leadership. Multiple logistic regression analyses were conducted, adjusting for factors in private life, employment category, labour-market sector, working conditions, self-reported general health, and satisfaction with life in general. Results: Inspirational leadership was associated with a lower rate of short spells of sickness absence (<1 week) for both men and women. Autocratic leadership was related to a greater amount of total sick days taken by men. Sometimes showing integrity was associated with higher rate of sickness absence >1 week among men, and seldom showing integrity was associated with more sickness presenteeism among women. Managers performing Team integration were sometimes associated with women taking fewer short (<1 week) and long (>1 week) spells of sickness absence. Adjustment for self-reported general health did not alter these associations for men, but did so to some extent for women. Conclusions: Managerial leadership was found to be relevant for the understanding of sickness absence in the Swedish working population. There were distinctive gender differences.
Beyond groups: seven pillars of peopled ethnography in organizations and communities
Authors: Brown-Saracino Japonica , Thurk Jessica , Fine Gary Alan
Published: November 2008

We extend Fine's (2003) model of `peopled ethnography' for studying small groups to the study of larger social units, including organizations and communities. While studies of small groups often recognize the presence of macro-level social structures, they typically treat these as backdrops to the interaction scene which constrain and enable group life, not as units of analysis in their own right. Yet small groups are embedded in and help constitute larger units of analysis, such as organizations and communities. We argue that studies of these larger social structures can be extended beyond ethnographic observation of the interactions that help comprise them, making peopled ethnography applicable to units of analysis larger than the small group. We offer illustrative examples of organizational and community ethnographies.
The intentionality of insight
Authors: Kelly Angela
Published: November 2008

Rather than duplicating biomedical research measuring insight, or suggesting models by which one could more reliably measure a person with dementia's insight, I turn to the notion of insight reflexively. Based on ethnographic research with four `intimate circles of care', I explore the consciousness of people with AIDS dementia's insight, the intentionality of insight in the phenomenological sense. Since insight is a capacity of all humans, I also include in my unit of analysis the meanings of insight for significant others. With intentionality, what matters most are the meanings made of and the positions taken towards insight. I do not address what we understand philosophically as knowledge or question the definitions of awareness or insight. I focus on the ethnographic description of the meanings and positions that informants had of insight. Intentionality is not necessarily truth or fact, but rather a position taken. From the meanings and positions taken by informants, four themes of the intentionality of insight emerged: insight as heart-wrenching; agency, control and purpose; the hope of losing insight; and insight as life-giving. Intentionality of insight emerged in relation to intimacy, emotions and relationships. Insight was experienced within and narrated through a liminal state.