NH4+ secretion in inner medullary collecting duct in potassium deprivation: role of colonic H+-K+-ATPase

NH4+ secretion in inner medullary collecting duct in potassium deprivation: Role of colonic H+-K+-ATPase. BACKGROUND: In K+ deprivation (KD), gastric (g) H+-K+-ATPase (HKA) is suppressed, whereas colonic (c) HKA is induced in the terminal inner medullary collecting duct (IMCD). We hypothesized that in KD, cHKA is induced and can mediate the secretion of NH4+. METHODS: Rats were sacrificed after 2, 3, 6, or 14 days on regular (NML) or K+-free (KD) diet. mRNA expression of HKA isoforms in terminal inner medulla was examined and correlated with NH4+ secretion in perfused IMCD in vitro. RESULTS: Urinary NH4+ excretion increased after K+-free diet for six days. In terminal inner medulla, cHKA expression was strongly induced, whereas gHKA expression was decreased. NH4+ secretion increased by 62% in KD (JtNH4+ 0.57 vs. 0.92 pmol/min/mm tubule length, P < 0.001). Ouabain (1 mM) in perfusate inhibited NH4+ secretion in KD by 45% (P < 0.002) but not in NML. At luminal pH 7.7, which inhibits NH3 diffusion, NH4+ secretion in IMCD was 140% higher in KD (0.36 vs. 0.15, P < 0.03) and was sensitive to ouabain. ROMK-1 mRNA expression was induced in parallel with cHKA in inner medulla. CONCLUSIONS: These data suggest that in KD, cHKA replaces gHKA and mediates enhanced secretion of NH4+ (and H+) into the lumen facilitated by K+ recycling through ROMK-1.     

Optimization of CO2 Sorption onto Spent Shale with Diethylenetriamine (DETA) and Ethylenediamine (EDA)

A novel technique was employed to optimize the CO₂ sorption performance of spent shale at elevated pressure–temperature (PT) conditions. Four samples of spent shale prepared from the pyrolysis of oil shale under an anoxic condition were further modified with diethylenetriamine (DETA) and ethylenediamine (EDA) through the impregnation technique to investigate the variations in their physicochemical characteristics and sorption performance. The textural and structural properties of the DETA- and EDA- modified samples revealed a decrease in the surface area from tens of m²/g to a unit of m²/g due to the amine group dispersing into the available pores, but the pore sizes drastically increased to macropores and led to the creation of micropores. The N–H and C–N bonds of amine noticed on the modified samples exhibit remarkable affinity for CO₂ sequestration and are confirmed to be thermally stable at higher temperatures by thermogravimetric (TG) analysis. Furthermore, the maximum sorption capacity of the spent shale increased by about 100% with the DETA modification, and the equilibrium isotherm analyses confirmed the sorption performance to support heterogenous sorption in conjunction with both monolayer and multilayer coverage since they agreed with the Sips, Toth, Langmuir, and Freundlich models. The sorption kinetics confirm that the sorption process is not limited to diffusion, and both physisorption and chemisorption have also occurred. Furthermore, the heat of enthalpy reveals an endothermic reaction observed between the CO₂ and amine-modified samples as a result of the chemical bond, which will require more energy to break down. This investigation reveals that optimization of spent shale with amine functional groups can enhance its sorption behavior and the amine-modified spent shale can be a promising sorbent for CO₂ sequestration from impure steams of the natural gas.     

Synthetic Zeolites as Controlled‐Release Delivery Systems for Anti‐Inflammatory Drugs

Scientists have always been trying to use artificial zeolites to make modified‐release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10–20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment.     

Delivery of Exogenous miR-124 to Glioblastoma Multiform Cells by Wharton’s Jelly Mesenchymal Stem Cells Decreases Cell Proliferation and Migration,and Confers Chemosensitivity

MicroRNAs (miRs) are potential therapeutic targets in glioblastoma multiforme (GBM), but the difficulties associated with their delivery to tumor target cells have hampered their widespread use. Mesenchymal stem cells (MSCs) can migrate to the sites of cancers, including GBM and exert anti-tumor effects. In this study, it is shown that Wharton’s jelly-MSCs (WJ-MSCs) have the ability to deliver exogenous miRs to GBM cells and the functional impact of this delivery is characterized. It is found that the labeled miR-124, as an example for miR of interest, can be successfully delivered with WJ-MSCs to U87 GBM cells via dependent or exosome-independent processes. It is demonstrated that the delivered exogenous miR-124 significantly decreases the luciferase activity of the target gene CDK6. In addition, the delivered miR-124 enhances the chemosensitivity of GBM cells to temozolomide and decreases the migration of GBM cells. These results suggest that the use of exogenous miRNA delivery with the derived exosomes from WJ-MSCs may provide a novel approach for miRNA replacement therapy in GBM cancers.     

Effect of completion of cardiac rehabilitation on heart rate recovery

To evaluate the effects of a cardiac rehabilitation program on heart rate recovery after percutaneous transluminal coronary angioplasty, a historical cohort study was performed on 436 patients of whom 285 were grouped on completion of 5, 10, or 24 training sessions. All 3 groups showed significant improvements in heart rate recovery, peak heart rate during treadmill testing, and end-training heart rate, from baseline to follow-up. Heart rate recovery on follow-up correlated significantly with the number of completed exercise sessions. The number of sessions, baseline ejection fraction, and age were independent predictors of mean post-training heart rate recovery. The cardiac rehabilitation program had a significant effect on peak heart rate and heart rate recovery, regardless of the underlying characteristics of the patients.     

Job satisfaction and the factors affecting satisfaction in nurse educators: A systematic review

Objectives

The present study seeks to answer the following two questions: Are nurse educators satisfied with their job? What are the factors affecting job satisfaction in nurse educators?