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  • 1
    Electronic Resource
    Electronic Resource
    Coupling between proximal tubular transport processes (1977)
    Springer
    Pflügers Archiv 368 (1977), S. 245-252 
    Details
    ISSN: 1432-2013
    Keywords: Renal tubule ; H+ ion secretion ; Na+ coupled transport ; Ouabain ; SITS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The rate of active transport by the proximal renal tubule of amino acid (l-histidine), sugar (α-methyl-d-glycoside), H+ ions (glycodiazine), phosphate and para-aminohippurate was evaluated by measuring the zero net flux concentration difference (Δc) of these substances. In the case of calcium the electrochemical potential differenceΔc +zFci Δϕ/RT) was the criterion employed. The rate of isotonic Na+-absorption (JNa) was measured with the shrinking droplet method. The effect of ouabain on the transport of these substances was tested in the golden hamster and the effect of SITS (4-acetamido-4′isothiocyanatostilbene 2,2′-disulfonic acid) was observed in rats. Ouabain (1 mM) applied peritubularly incompletely inhibited JNa (80%), but in combination with acetazolamide (0.2 mM) the inhibition was almost complete (93%). In addition, ouabain inhibited the sodium coupled (secondary active) transport processes ofl-histidine, α-methyl-d-glycoside, calcium and phosphate by more than 75%. It did not affect H+ (glycodiazine) transport and PAH transport was only slightly affected. When SITS (1 mM) was applied from both sides of the cell it inhibited H+ (glycodiazine) transport by 72% and reduced JNa by 38% when given from only the peritubular cell side. SITS (1 mM), however, had no significant affect on H+ secretion and sodium reabsorption if it was applied from only the luminal side. Furthermore it had no affect on the other transport processes tested, regardless of the cell side to which it was applied. When the HCO 3 − buffer or physically related buffers were omitted from the perfusate the absorption of Na+ was reduced by 66%, phosphate by 44%, andl-histidine by 15%. All the other transport processes tested were not significantly affected. The data are consistent with the hypothesis that the active transport processes of histidine, α-methyl-d-glycoside and phosphate, which are located in the brush border, are driven by a sodium gradient which is abolished by ouabain. This may also apply to the Na+-Ca2+ countertransport located at the contraluminal cell side. The residual Na+ transport remaining in the presence of ouabain is likely to be passively driven by the continuing H+ transport which probably is driven directly by ATP. SITS seems to inhibit the exit step of HCO 3 − from the cell and secondary to that, the luminal H+-Na+ exchange and consequently the Na+ reabsorption. In the absence of HCO 3 − buffer in the perfusates the luminal H+-Na+ exchange seems to be affected and the pattern of inhibition of the other transport processes is almost the same as with SITS. The different effects onP i reabsorption observed under these conditions might be explained by possible variations in intracellular pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585203
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  • 2
    Electronic Resource
    Electronic Resource
    Intracellular pH in renal tubules in situ: single-cell measurements by confocal laserscan microscopy (1993)
    Springer
    Pflügers Archiv 422 (1993), S. 523-529 
    Details
    ISSN: 1432-2013
    Keywords: Confocal microscopy ; Fluorescence microscopy ; Proximal tubule ; 2′,7′-Bis(carboxyethyl)-5(6)-carboxyfluorescein ; Intracellular pH ; Viability ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Confocal laserscan microscopy with a dual-excitation device was used to record intracellular pH (pHi) regulation in rat proximal convoluted tubules microperfused in vivo. Cells were loaded with the pH-sensitive, fluorescent dye 2′,7′-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Single cells could be distinguished within the tubules and separate measurements were possible. Application of an NH4Cl pulse by peritubular perfusion caused an immediate increase in intracellular pH. Intraluminal injection of NH4Cl led to a slower increase in intracellular pH. In both cases, cessation of perfusion led to an immediate acidification. Peritubular perfusion with 300 μM 4,4′-diisothiocanatodihydrostilbene-2, 2′-disulphonic acid (H2DIDS) caused an intracellular alkalinisation. Microperfusion, pH-sensitive dyes and confocal laserscan microscopy provide a new non-invasive method to measure intracellular pH effectively in individual cells of near-surface structures of the intact kidney.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375081
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  • 3
    Electronic Resource
    Electronic Resource
    AUTHORS REPLY (1999)
    Springer
    International orthopaedics 23 (1999), S. B131 
    Details
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The disappearing exostosis? (1998)
    Springer
    International orthopaedics 22 (1998), S. 59-61 
    Details
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. Nous rapportons l’observation, d’une jeune fille de 11 ans qui presentait une néoformation au niveau de la métaphyse proximale du tibia droit, avec les caracteristiques cliniques et radiographiques d’une exostose sessile. Cette néoformation était asymptomatique et ne fut pas operée: on a conseillé des controles periodiques seulement. Après 32 mois il n’y avait plus aucune trace de cette exostose au controle clinique et radiographique. On peut penser à une involution spontanée de la néoformation, compte tenu de l’âge de cette fille.
    Notes: Summary. A girl aged 11 years was referred to us with a medial upper right tibial exostosis. As the lesion was asymptomatic, surgery was not undertaken. The patient defaulted from follow up, and, when reviewed 32 months later, there was no clinical or radiographic evidence of the exostosis. Spontaneous involution of an exostosis may occasionally occur in childhood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002640050209
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  • 5
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    A fate-mapping approach reveals the composite origin of the connecting tubule and alerts on "single-cell"-specific KO model of the distal nephron (2016)
    The American Physiological Society (APS)
    Details
    Publication Date: 2016-11-03
    Description: The distal nephron is a heterogeneous part of the nephron composed by six different cell types, forming the epithelium of the distal convoluted (DCT), connecting, and collecting duct. To dissect the function of these cells, knockout models specific for their unique cell marker have been created. However, since this part of the nephron develops at the border between the ureteric bud and the metanephric mesenchyme, the specificity of the single cell markers has been recently questioned. Here, by mapping the fate of the aquaporin 2 (AQP2) and Na + -Cl – cotransporter (NCC)-positive cells using transgenic mouse lines expressing the yellow fluorescent protein fluorescent marker, we showed that the origin of the distal nephron is extremely composite. Indeed, AQP2-expressing precursor results give rise not only to the principal cells, but also to some of the A- and B-type intercalated cells and even to cells of the DCT. On the other hand, some principal cells and B-type intercalated cells can develop from NCC-expressing precursors. In conclusion, these results demonstrate that the origin of different cell types in the distal nephron is not as clearly defined as originally thought. Importantly, they highlight the fact that knocking out a gene encoding for a selective functional marker in the adult does not guarantee cell specificity during the overall kidney development. Tools allowing not only cell-specific but also time-controlled recombination will be useful in this sense.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
    Published by The American Physiological Society (APS)
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  • 6
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    NEMO Is Essential for Thyroid Function [Signal Transduction] (2016)
    The American Society for Biochemistry and Molecular Biology (ASBMB)
    Details
    Publication Date: 2016-03-12
    Description: The I-κB kinase (IKK) subunit NEMO/IKKγ (NEMO) is an adapter molecule that is critical for canonical activation of NF-κB, a pleiotropic transcription factor controlling immunity, differentiation, cell growth, tumorigenesis, and apoptosis. To explore the functional role of canonical NF-κB signaling in thyroid gland differentiation and function, we have generated a murine strain bearing a genetic deletion of the NEMO locus in thyroid. Here we show that thyrocyte-specific NEMO knock-out mice gradually develop hypothyroidism after birth, which leads to reduced body weight and shortened life span. Histological and molecular analysis indicate that absence of NEMO in thyrocytes results in a dramatic loss of the thyroid gland cellularity, associated with down-regulation of thyroid differentiation markers and ongoing apoptosis. Thus, NEMO-dependent signaling is essential for normal thyroid physiology.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
    Published by The American Society for Biochemistry and Molecular Biology (ASBMB)
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  • 7
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    Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+AT (Slc7a9) in mice (2013)
    The American Physiological Society (APS)
    Details
    Publication Date: 2013-12-16
    Description: Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT ) and SLC7A9 ( b 0,+ AT ). Gene targeting of the catalytic subunit ( Slc7a9 ) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b 0,+ . No remarkable gene expression changes were observed in other amino acid transporters and the peptide transporters in the intestine and kidney. Furthermore, the glomerular filtration rate (GFR) was reduced by 30% in knockout animals compared with wild-type animals. The fractional excretion of arginine was increased as expected (~100%), but fractional excretions of lysine (~35%), ornithine (~16%), and cystine (~11%) were less affected. Loss of function of b 0,+ AT reduced transport of cystine and arginine in renal BBMVs and completely abolished the exchanger activity of dibasic amino acids with neutral amino acids. In conclusion, loss of Slc7a9 function decreases the GFR and increases the excretion of several amino acids to a lesser extent than expected with no clear regulation at the mRNA and protein level of alternative transporters and no increased renal epithelial uptake. These observations indicate that transporters located in distal segments of the kidney and/or metabolic pathways may partially compensate for Slc7a9 loss of function.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
    Published by The American Physiological Society (APS)
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  • 8
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    Evaluation of cellular plasticity in the collecting duct during recovery from lithium-induced nephrogenic diabetes insipidus (2013)
    The American Physiological Society (APS)
    Details
    Publication Date: 2013-09-16
    Description: The cellular morphology of the collecting duct is altered by chronic lithium treatment. We have previously shown that lithium increases the fraction of type-A intercalated cells and lowers the fraction of principal cells along the collecting duct. Moreover, type-A intercalated cells acquire a long-row distribution pattern along the tubules. In the present study, we show that these morphological changes reverse progressively after discontinuation of lithium and finally disappear after 19 days from lithium suspension. In this time frame we have identified for the first time, in vivo, a novel cellular type positive for both intercalated and principal cells functional markers, as recognized by colabeling with H + -ATPase/aquaporin-4 (AQP4) and anion exchanger-1 (AE-1)/AQP2 and Foxi1/AQP4. This cell type is mainly present after 6 days of lithium washout, and it disappears in parallel with the long-row pattern of the type-A intercalated cells. It usually localizes either in the middle or at the edge of the long-row pattern. Its ultrastructure resembles the intercalated cells as shown both by differential interference contrast and by electron microscopy. The time course of appearance, the localization along the collecting duct, and the ultrastructure suggest that the cells double labeled for principal and intercalated cells markers could represent a transition element driving the conversion of intercalated cells into principal cells.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
    Published by The American Physiological Society (APS)
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  • 9
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    Renal phenotype in Bardet-Biedl syndrome: a combined defect of urinary concentration and dilution is associated with defective urinary AQP2 and UMOD excretion (2016)
    The American Physiological Society (APS)
    Details
    Publication Date: 2016-10-08
    Description: The renal phenotype in Bardet-Biedl syndrome (BBS) is highly variable. The present study describes renal findings in 41 BBS patients and analyzes the pathogenesis of hyposthenuria, the most common renal dysfunction. Five of 41 patients (12%) showed an estimated glomerular filtration rate 〈 60 ml·min –1 ·1.73 m –2 . Urine protein and urine albumin-to-creatinine ratio were over 200 and 30 mg/g in 9/24 and 7/23 patients, respectively. Four of 41 patients showed no renal anomalies on ultrasound. Twenty of 34 patients had hyposthenuria in the absence of renal insufficiency. In all 8 of the hyposthenuric patients studied, dDAVP failed to elevate urine osmolality (Uosm), suggesting a nephrogenic origin. Interestingly, water loading (WL) did not result in a significant reduction of Uosm, indicating combined concentrating and diluting defects. dDAVP infusion induced a significant increase of plasma Factor VIII and von Willebrand Factor levels, supporting normal function of the type 2 vasopressin receptor at least in endothelial cells. While urinary aquaporin 2 (u-AQP2) abundance was not different between patients and controls at baseline, the dDAVP-induced increased u-AQP2 and the WL-induced reduction of u-AQP2 were blunted in patients with a combined concentrating and diluting defect, suggesting a potential role of AQP2 in the defective regulation of water absorption. Urine Uromodulin excretion was reduced in all hyposthenuric patients, suggesting a thick ascending limb defect. Interestingly, renal Na, Cl, Ca, but not K handling was impaired after acute WL but not at basal. In summary, BBS patients show combined urinary concentration and dilution defects; a thick ascending limb and collecting duct tubulopathy may underlie impaired water handling.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
    Published by The American Physiological Society (APS)
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  • 10
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    Nitrogen isotope measurements on hydrothermal fluids from Azores (S. Miguel, Terceira and Graciosa) Islands, Portugal (2010)
    International Association of Geochemistry
    Details
    Publication Date: 2021-01-27
    Description: We present the first nitrogen isotope data from hydrothermal fluids of Graciosa, Terceira and S. Miguel Islands (Azores, Portugal), together with helium isotope composition. 15N values are slightly enriched in light isotopes (from -0.7‰ to -2.2‰) with respect to air, while 3He/4He ratios range from 5 to 6 Ra in Sao Miguel island and from 8 to 9.1 Ra in Graciosa and Terceira islands. The latter values are similar to those found in olivine phenocrysts of basalts (Moreira et al., 1999; Madureira et al., 2005). Such isotope signatures seem to point to the presence of two different deeply-derived end-members: a 3He-rich primitive end-member evident in Terceira and Graciosa islands samples and a 3He-poor end-member characterizing samples from S. Miguel island. According to Madureira et al. (2005), the He primitive component which is more evident in the central parts of the Azores archipelago has to be related to a lower mantle contribution into the prevailing MORB component. On the contrary, the origin of the radiogenic crustal component is still open and debated between the contribution of recycled terrigenous sediments (Turner et al., 1997) and oceanic mantle lithosphere (Schaefer et al., 2002). Since 15N values from fluids vents and inclusions in basalt glasses were discovered to be good geochemical tracers of magma genetic processes, we determined molecular and isotope nitrogen composition (15NN2) in some hydrothermal fluids with the aim to provide additional information on the mantle composition beneath the Azores archipelago. Based on the N2/36Ar ratio we computed for each samples the 15N values of the non-atmospheric nitrogen (15Ndeep). Volatiles emitted from Graciosa and Terceira islands seem to have a common deep nitrogen isotope signature of about -1.5‰ likely resulting from a mixing between lower mantle (15N from 1‰ to 4‰) and upper mantle (15NMORB from -3‰ to -7‰). On the other hand, the 15Ndeep feeding the fumaroles at S. Miguel is close to -5.5‰. Such a 15N-depleted values seem to indicate a probable nitrogen origin from a deep source derived from the recycling of ancient oceanic plate into the upper mantle (MORB). rather than from the recycling of terrigenous sediments transported on top of the descending plate that should have lead to 15N-enrichments.
    Description: Published
    Description: La Malbaie, Quebec, Canada
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 3.2. Tettonica attiva
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: open
    Keywords: Nitrogen isotopes ; Hydrothermal fluids ; Azores Islands ; Volcanic gases ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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