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Claudin-2 is highly expressed in tight junctions of mouse renal proximal tubules, which possess a leaky epithelium whose unique permeability properties underlie their high rate of NaCl reabsorption. To investigate the role of claudin-2 in paracellular NaCl transport in this nephron segment, we generated knockout mice lacking claudin-2 (Cldn2⁻/⁻). The Cldn2⁻/⁻ mice displayed normal appearance, activity, growth, and behavior. Light microscopy revealed no gross histological abnormalities in the Cldn2⁻/⁻ kidney. Ultrathin section and freeze-fracture replica electron microscopy revealed that, similar to those of wild types, the proximal tubules of Cldn2⁻/⁻ mice were characterized by poorly developed tight junctions with one or two continuous tight junction strands. In contrast, studies in isolated, perfused S2 segments of proximal tubules showed that net transepithelial reabsorption of Na⁺, Cl⁻, and water was significantly decreased in Cldn2⁻/⁻ mice and that there was an increase in paracellular shunt resistance without affecting the apical or basolateral membrane resistances. Moreover, deletion of claudin-2 caused a loss of cation (Na⁺) selectivity and therefore relative anion (Cl⁻) selectivity in the proximal tubule paracellular pathway. With free access to water and food, fractional Na⁺ and Cl⁻ excretions in Cldn2⁻/⁻ mice were similar to those in wild types, but both were greater in Cldn2⁻/⁻ mice after i.v. administration of 2% NaCl. We conclude that claudin-2 constitutes leaky and cation (Na⁺)-selective paracellular channels within tight junctions of mouse proximal tubules.

Skin dryness associated with type 2 diabetes worsens with age; however, the underlying mechanisms remain unclear. Herein, we investigated the effects of aging on skin dryness using a type 2 diabetes mice model. Specific pathogen-free KK-Ay/TaJcl mice of different ages (10, 27, 40, and 50 weeks) were used in this study. The results confirmed that skin dryness worsens with age. Furthermore, increased levels of advanced glycation end products (AGE), prostaglandin E2 (PGE2), and tumor necrosis factor (TNF)-α, along with an increased expression of the major AGE receptor (RAGE), an increased macrophage number, and decreased collagen expression were observed in the skin of aged KK-Ay/TaJcl mice. In conclusion, dry skin conditions worsen with age in diabetic mice, and the AGE/RAGE/PGE2 and TNF-α pathways play an important role in exacerbating skin dryness during aging in these mice.

The onset and exacerbation of dementia have been observed in elderly patients with type 2 diabetes. However, the underlying mechanism remains unclear. In this study, we investigated the effects of aging on the cognitive function in a mouse model of type 2 diabetes. Pathogen-free KK-Ay/TaJcl mice were used in this study. The cognitive abilities and memory declined in the mice and worsened in the 50-week-olds. The levels of advanced glycation end products (AGEs), receptor for AGE (RAGE), and Iba1 in the hippocampus were increased in the mice compared to those in the control mice. Hippocampal levels of CC-chemokine receptor 7 and inducible nitric oxide synthase, which are from M1-type macrophages that shift from microglia, were higher in KK-Ay/TaJcl mice than in control mice. Tumor necrosis factor (TNF)-α and nitric oxide (NO) levels secreted by M1-type macrophages were similarly elevated in the mice and were even higher at the age of 50 weeks. NO levels were markedly elevated in the 50-week-old mice. In contrast, differentiation of CD163 and arginase-1 did not change in both mouse types. Memory and learning declined with age in diabetic mice, and the AGEs/RAGE/M1-type macrophage/NO and TNF-α pathways played an important role in exacerbating memory and learning in those mice.

In the event of a disaster, the chain of command and communication of each relevant agency is important. In this study, a chronological record creation system using voice AI (V-CRS) was developed, and an experiment was conducted to determine whether the obtained information could be quickly and easily summarized in chronological order. After a lecture by Japanese Disaster Medical Assistant (DMAT) Team members and 8 medical clerks on how to use the developed tool, a comparison experiment was conducted between manual input and V-CRS utilization of the time to compile disaster information. Results proved that V-CRS can collect information gathered at headquarters more quickly than handwriting. It was also suggested that even medical clerks who have never been trained to record information during disasters could record information at the same speed as trained DMAT personnel. V-CRS can transcribe audio information even in situations where technical terms and physical units must be recorded, such as radiation disasters. It has been proven that anyone can quickly organize information using this method, to some extent.

Tumor metastasis is closely associated with coagulation and inflammation, particularly via thrombin–PAR1 signaling. However, the potential of natural polysaccharides such as rhamnan sulfate (RS) to modulate these pathways and suppress metastasis remains unclear. We aimed to investigate the effects of orally administered RS derived from Monostroma nitidum on melanoma metastasis and its underlying mechanisms. Male C57BL/6J mice were orally administered water or RS daily. On day 8, saline or B16 melanoma cells were injected intravenously. Mice were treated for 21 days and divided into four groups (control, RS-only, M + W, and M + RS; n = 5/group). Metastasis and related molecular factors were analyzed in plasma, lung, and aortic tissues. Significant lung and aortic metastases were observed in the M + W group but were markedly suppressed in the M + RS group. RS reduced the expression of inflammatory factors (e.g., IL-6, PAR1), proteases, leukocyte activation markers, complement factors, angiogenic factors, and EMT-related factors. Conversely, thrombin, thrombomodulin, plasmin, TAFIa, and tight junction proteins were increased in RS-treated mice. RS suppresses melanoma metastasis by modulating thrombin–PAR1-mediated inflammation and associated pathways. These findings suggest RS as a potential therapeutic agent, although further mechanistic and clinical studies are required.

Although urea and water are transported across separate pathways in the apical membrane of the inner medullary collecting duct (IMCD), the existence of a cellular diffusion barrier as an unstirred layer makes it possible to use coefficients of effective osmotic force (sigma*) as equivalent to reflection coefficients. The difference in effective osmolality between urea and NaCl across the IMCD becomes a driving force for water if the compositions of solutes are different between tubular lumen and interstitium. Since reported values for sigma*(urea) are discrepant, we compared the efficiency of a single effect in the counter-current system between an ascending thin limb (ATL) and the IMCD, with the interposition of capillary networks (CNW), between two models with sigma(urea)* = 0.7 (model 1) and sigma(urea)* = 1.0 (model 2). The time courses (within 3 s) of solute and the water transport profiles among ATL, CNW, and IMCD were simulated with a computer in the absence of flow in each compartment. In spite of small differences in the profiles of urea and NaCl concentrations between the two models, model 1 displayed a larger volume flux in the IMCD than model 2, resulting in an increase of osmolality in the IMCD and a decrease of osmolality in the ATL. These findings are vital for the operation of the counter-current multiplication system. The concept of coefficients for effective osmotic force can be applied to the counter-current model between the IMCD and the ATL with the interposition of CNW. The model of sigma(urea)* = 0.7 is more efficient than that of sigma(urea)* = 1.0.

“Avian-type” renal medullary tubule organization causes immaturity of urine-concentrating ability in neonates. While 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. Analyses 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. On 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. We 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.

Pendrin, an anion exchanger known to participate in iodide transport in the apical membrane of follicular cells of the thyroid gland, has recently been shown to exist in the apical membrane of the beta- and gamma-intercalated (beta/gamma-IC) cells of the cortical collecting duct (CCD). We examined mechanisms of iodide transport in the CCD. Rabbit CCD was perfused in vitro, and lumen-to-bath flux coefficients for both (125)I(-) (K(I (lb))) and (36)Cl(-) (K(Cl (lb))) were measured simultaneously. The intracellular pH (pHi) of beta/gamma-IC cells in the perfused CCD was measured by microscopic fluorometory, by loading 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein tetraacetoxy methylester (BCECF-AM), a fluorescent marker for pHi. The effects on pHi of the replacement of NaCl with Na cyclamate, NaI, or NaBr in the lumen or bath were observed. K(I (lb)) was comparable to or slightly higher than K(Cl (lb)). Both iodide and chloride in the lumen caused self- and cross-inhibitions to both fluxes. The addition of 5-nitro-2-(-3-phenylpropylamino)-benzoate (NPPB), a Cl(-) channel inhibitor, to the bath significantly reduced K(Cl (lb)), but not K(I (lb)). Replacement of luminal fluid NaCl with Na cyclamate, NaI, or NaBr caused alkalization of pHi, no change in pHi, and slight acidification of pHi, respectively. Replacement of bath NaCl with Na cyclamate, NaI, or NaBr caused alkalization, alkalization, and acidification of pHi, respectively. Luminal NaI prevented the acidification of pHi caused by bath Na cyclamate. The data are consistent with the model that iodide is transported via the Cl(-)/HCO(3) (-) exchanger in the apical membrane of beta/gamma-IC cells and exits the basolateral membrane via an electroneutral transporter that is distinct from the Cl(-) channel. We could not, however, identify which type of beta/gamma-IC cell was mainly responsible.

Specific therapy of digoxin intoxication in dogs by hybrid kidney overexpressing multidrug resistance protein. We have recently developed a unique hybrid artificial kidney, where the proximal tubular cell line, over-expressing multidrug resistance protein, MDR-1 (PCTL-MDR), was cultured on hollow fibers. While this module efficiently removed digoxin in vitro, its efficacy in vivo remained to be determined. The system was scaled up by connecting 10 similar modules in parallel, with the MDR-1 (PCTL-MDR) overexpressed proximal tubular cell line cultured as in our previous study. The system was connected to dogs intoxicated with digoxin, a representative substrate of MDR-1. Blood was circulated for 90 minutes through the system. Arterial and venous blood concentrations of digoxin and inulin were monitored. Complete blood cell count and granulocyte elastase were measured before and at the end of the study. By using the system with PCTL-MDR, the arterial digoxin concentration was dramatically decreased from 2.89 ± 0.10 to 0.92 ± 0.11 ng/mL, but not by the system with PCTL alone. The clearance was 22.4 ± 2.1 and 1.5 ± 0.2mL/min for the PCTL-MDR and PCTL equipment, respectively. Inulin was not transported in either system. White blood cell and platelet counts were slightly reduced by the treatment while hematocrit was unchanged; the granulocyte elastase concentration was slightly increased. These data suggest that our new type of hybrid kidney can selectively remove digoxin sufficiently to reduce its systemic blood concentration in dogs with digoxin intoxication. Taking previous studies into consideration, this system may be a more powerful tool for the treatment of intoxication.