Cell Ca2+ response to luminal vasopressin in cortical collecting tubule principal cells

Cell Ca2+ response to luminal vasopressin in cortical collecting tubule principal cells. Although vasopressin V1 receptors have been shown to exist in both luminal and basolateral membranes of rabbit cortical collecting duct (CCD), exact cell types having V1 receptors remain unestablished. To identify the distribution of V1 receptor by cytoplasmic Ca2+ response, we utilized the confocal imaging system in the microperfused rabbit CCD. Basolateral application of arginine vasopressin (AVP) increased [Ca2+]i mainly in one group of cells which were not stained by fluorescein-isothiocyanate-conjugated peanut agglutinin. Luminal application of AVP increased [Ca2+]i in the same cells which responded to basolateral AVP. These findings provide evidence that V1 receptors, as defined by the [Ca2+]i response, exist in both luminal and basolateral membranes of the rabbit principal cell

“Avian-type” renal medullary tubule organization causes immaturity of urine-concentrating ability in neonates

“Avian-type” renal medullary tubule organization causes immaturity of urine-concentrating ability in neonates.BackgroundWhile neonatal kidneys are not powerful in concentrating urine, they already dilute urine as efficiently as adult kidneys. To elucidate the basis for this paradoxical immaturity in urine-concentrating ability, we investigated the function of Henle's loop and collecting ducts (IMCDs) in the inner medulla of neonatal rat kidneys.MethodsAnalyses of individual renal tubules in the inner medulla of neonatal and adult rat kidneys were performed by measuring mRNA expression of membrane transporters, transepithelial voltages, and isotopic water and ion fluxes. Immunofluorescent identification of the rCCC2 and rCLC-K1 using polyclonal antibodies was also performed in neonatal and adult kidney slices.ResultsOn day 1, the transepithelial voltages (VTs) in the thin ascending limbs (tALs) and IMCDs were 14.6 ± 1.1mV (N = 27) and -42.7 ± 6.1mV (N = 14), respectively. The VTs in the thin descending limbs (tDLs) were zero on day 1. The VTs in the tALs were strongly inhibited by luminal bumetanide or basolateral ouabain, suggesting the presence of a NaCl reabsorption mechanism similar to that in the thick ascending limb (TAL). The diffusional voltage (VD) of the tAL due to transepithelial NaCl gradient was almost insensitive to a chloride channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB). The VTs in the IMCDs were strongly inhibited by luminal amiloride.On day 1, both the tDL and tAL were impermeable to water, indicating the water impermeability of the entire loop. Diffusional water permeability (Pdw) and urea permeabilities (Purea) in the IMCDs indicated virtual impermeability to water and urea on day 1. Stimulation by vasopressin (1nmol/L) revealed that only Pdw was sensitive to vasopressin by day 14. A partial isoosmolar replacement of luminal urea by NaCl evoked negligible water flux across the neonatal IMCDs, indicating the absence of urea-dependent volume flux in the neonatal IMCD. These transport characteristics in each neonatal tubule are similar to those in quail kidneys. Identification of mRNAs and immunofluorescent studies for specific transporters, including rAQP-1, rCCC2, rCLC-K1, rENaC β subunit, rAQP-2, and rUT-A1, supported these findings.ConclusionWe hypothesize that the renal medullary tubule organization of neonatal rats shares a tremendous similarity with avian renal medulla. The qualitative changes in the organization of medullary tubules may be primarily responsible for the immature urine-concentrating ability in mammalian neonates

Mechanism of Cd-Induced Inhibition of Na-Glucose Cotransporter in Rabbit Proximal Tubule Cells: Roles of Luminal pH and Membrane-Bound Carbonic Anhydrase

Background/Aims: We have previously reported that a complex of cadmium-metallothionein (Cd-MT) directly affects the apical Na-glucose cotransporter on the luminal side in proximal tubules, suggesting that Cd-MT is more toxic than CdCl2 in causing tubulopathy. To find the potential mechanisms, we evaluated the effect of luminal pH alteration and carbonic anhydrase (CA) inhibition on Cd-MT-induced reduction of glucose-dependent transmural voltage in rabbit S2 segments perfused in vitro. Methods: Before and after the addition of Cd-MT (1 µg Cd/ml) to the lumen, the deflections of transmural voltage upon the elimination of glucose from the perfusate (DeltaVtglu) were measured as a parameter of activity of the Na-glucose cotransporter. Results: During perfusion with a control solution of pH 7.4, the DeltaVtglu significantly decreased after addition of Cd-MT for 10 min. A reduction in pH to 6.8 significantly shortened the time needed to reduce the DeltaVtglu to 20 min. Furthermore, simultaneous addition of acetazolamide with control perfusate prevented the reduction. P-Fluorobenzyl-aminobenzolamide (pFB-ABZ), a membrane-impermeable CA inhibitor, added to the lumen also completely prevented the reduction in DeltaVtglu. In rabbits with chronic Cd exposure, acetazolamide prevented the glucosuria. Conclusion: Cd-MT-induced inhibition of Na-glucose cotransporter activity in the S2 segment strongly depends on luminal pH, and that an increase in pH by inhibition of luminal membrane-bound CA is useful to prevent renal Cd toxicity

Stomagen positively regulates stomatal density in Arabidopsis.

葉の気孔の数を増加させる因子の発見～CO2削減や食糧増産へ向けて～. 京都大学プレスリリース. 2009-12-10.Stomata in the epidermal tissues of leaves are valves through which passes CO(2), and as such they influence the global carbon cycle. The two-dimensional pattern and density of stomata in the leaf epidermis are genetically and environmentally regulated to optimize gas exchange. Two putative intercellular signalling factors, EPF1 and EPF2, function as negative regulators of stomatal development in Arabidopsis, possibly by interacting with the receptor-like protein TMM. One or more positive intercellular signalling factors are assumed to be involved in stomatal development, but their identities are unknown. Here we show that a novel secretory peptide, which we designate as stomagen, is a positive intercellular signalling factor that is conserved among vascular plants. Stomagen is a 45-amino--rich peptide that is generated from a 102-amino-acid precursor protein designated as STOMAGEN. Both an in planta analysis and a semi-in-vitro analysis with recombinant and chemically synthesized stomagen peptides showed that stomagen has stomata-inducing activity in a dose-dependent manner. A genetic analysis showed that TMM is epistatic to STOMAGEN (At4g12970), suggesting that stomatal development is finely regulated by competitive binding of positive and negative regulators to the same receptor. Notably, STOMAGEN is expressed in inner tissues (the mesophyll) of immature leaves but not in the epidermal tissues where stomata develop. This study provides evidence of a mesophyll-derived positive regulator of stomatal density. Our findings provide a conceptual advancement in understanding stomatal development: inner photosynthetic tissues optimize their function by regulating stomatal density in the epidermis for efficient uptake of CO(2)

Finding Neighbor Communities in the Web Using an Inter-Site Graph

In this paper, we present Neighbor Community Finder (NCF, for short), a tool for finding Web communities related to given URLs. While existing link-based methods of finding communities, such as HITS, trawling, and Companion, use algorithms running on a Web graph whose vertices are pages and edges are links on the Web, NCF uses an algorithm running on an inter-site graph whose vertices are sites and edges are global-links (links between sites). Since the phrase "Web site" is used ambiguously in our daily life and has no unique definition, NCF uses directory-based sites proposed by the authors as a model of Web sites. NCF receives URLs interested in by a user and constructs an inter-site graph containing neighbor sites of the given URLs by using a method of identifying directory-based sites from URL and link data obtained from the actual Web on demand. By computational experiments, we show that NCF achieves higher quality than Google\u27s "Similar Pages" service for finding pages related to given URLs corresponding to various topics selected from among the directories of Yahoo! Japan.PAPE

Navigated pin-point approach to osteoid osteoma adjacent to the facet joint of spine

Osteoid osteoma (OO) is a benign osteoblastic tumor. Its curative treatment is complete removal of the nidus, where intraoperative localization of the nidus governs clinical results. However, treatment can be difficult since the lesion is often invisible over the bony surface. Accordingly, establishment of an ideal less invasive surgical strategy for spinal OO remains yet unsettled. We illustrate the efficacy of a computed tomography (CT)-based navigation system in excising OO located adjacent to the facet joint of spine. In our 2 cases, complete and pin-point removal of the nidus located close to the facet joint was successfully achieved, without excessive removal of the bone potentially leading to spinal instability and possible damage of nearby neurovascular structures. We advocate a less invasive approach to spinal OO, particularly in an environment with an available CT-based navigation system

Compact Encoding of the Web Graph Exploiting Various Power Distributions

Compact encodings of the web graph are required in order to keep the graph on the main memory and to perform operations on the graph efficiently. In this paper, we propose a new compact encoding of the web graph. It is 10% more compact than Link2 used in the Connectivity Server of Altavista and 20% more compact than the encoding proposed by Guillaume et al. in 2002 and is comparable to it in terms of extraction time.Special Section LETTER (Special Section on Discrete Mathematics and Its Applications

Super responder of critical COVID-19 case

This report presents a case of a 74-year-old man who showed dramatic therapeutic response to treatment of coronavirus infectious disease-19 (COVID-19) pneumonia. He reported four-day history of sustained fever and acute progressive dyspnea. He developed severe respiratory failure, underwent urgent endotracheal intubation and showed marked elevation of inflammatory and coagulation markers such as c-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH) and D-dimer. Chest computed tomography (CT) demonstrated diffuse consolidation and ground glass opacity (GGO). We diagnosed critical COVID-19 pneumonia with detailed sick contact history and naso-pharyngeal swab of a reverse-transcriptase-polymerase-chain reaction (RT-PCR) assay testing. He received anti-viral drug, anti-interleukin (IL-6) receptor antagonist and intravenous methylprednisolone. After commencing combined intensive therapy, he showed dramatic improvement of clinical condition, serum biomarkers and radiological findings. Early diagnosis and rapid critical care management may provide meaningful clinical benefit even if severe case